| Mapping | Rule Title | Description | Rationale |
|---|---|---|---|
| AU-2(d) AU-12(c) CM-6(a) |
Ensure auditd Collects File Deletion Events by User - unlink |
At a minimum, the audit system should collect file deletion events
for all users and root. If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following line to a file with suffix .rules in the
directory /etc/audit/rules.d, setting ARCH to either b32 or b64 as
appropriate for your system:
-a always,exit -F arch=ARCH -S unlink -F auid>=1000 -F auid!=unset -F key=deleteIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file, setting ARCH to either b32 or b64 as appropriate for your system: -a always,exit -F arch=ARCH -S unlink -F auid>=1000 -F auid!=unset -F key=delete |
Auditing file deletions will create an audit trail for files that are removed from the system. The audit trail could aid in system troubleshooting, as well as, detecting malicious processes that attempt to delete log files to conceal their presence. |
| AU-2(a) | Configure auditing of unsuccessful file creations (AArch64) |
Ensure that unsuccessful attempts to create a file are audited.
The following rules configure audit as described above:
## Unsuccessful file creation (open with O_CREAT) -a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b32 -S open -F a1&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b32 -S creat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b32 -S open -F a1&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b32 -S creat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-createLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Unsuccessful file creations might be a sign of a malicious action being performed on the system. Keeping log of such events helps in monitoring and investigation of such actions. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Access Attempts to Files - openat |
At a minimum, the audit system should collect unauthorized file
accesses for all users and root. If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S openat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b32 -S openat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S openat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b64 -S openat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S openat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b32 -S openat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S openat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b64 -S openat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=access |
Unsuccessful attempts to access files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Modification Attempts to Files - open_by_handle_at O_TRUNC_WRITE |
The audit system should collect detailed unauthorized file accesses for
all users and root. The open_by_handle_at syscall can be used to modify files
if called for write operation of with O_TRUNC_WRITE flag.
The following auidt rules will asure that unsuccessful attempts to modify a
file via open_by_handle_at syscall are collected.
If the auditd daemon is configured to use the augenrules
program to read audit rules during daemon startup (the default), add the
rules below to a file with suffix .rules in the directory
/etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the rules below to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S open_by_handle_at -F a2&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b32 -S open_by_handle_at -F a2&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modificationIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S open_by_handle_at -F a2&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b64 -S open_by_handle_at -F a2&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification |
Unsuccessful attempts to access files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Permission Changes to Files - fremovexattr |
The audit system should collect unsuccessful file permission change
attempts for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the following lines to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S fremovexattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b32 -S fremovexattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-changeIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S fremovexattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b64 -S fremovexattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change |
Unsuccessful attempts to change permissions of files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Creation Attempts to Files - open O_CREAT |
The audit system should collect unauthorized file accesses for
all users and root. The open syscall can be used to create new files
when O_CREAT flag is specified.
The following auidt rules will asure that unsuccessful attempts to create a
file via open syscall are collected.
If the auditd daemon is configured to use the augenrules
program to read audit rules during daemon startup (the default), add the
rules below to a file with suffix .rules in the directory
/etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the rules below to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S open -F a1&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b32 -S open -F a1&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-createIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S open -F a1&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b64 -S open -F a1&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-create |
Unsuccessful attempts to access files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Access Attempts to Files - open |
At a minimum, the audit system should collect unauthorized file
accesses for all users and root. If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S open -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b32 -S open -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S open -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b64 -S open -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S open -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b32 -S open -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S open -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b64 -S open -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=access |
Unsuccessful attempts to access files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Creation Attempts to Files - open_by_handle_at O_CREAT |
The audit system should collect unauthorized file accesses for
all users and root. The open_by_handle_at syscall can be used to create new files
when O_CREAT flag is specified.
The following auidt rules will asure that unsuccessful attempts to create a
file via open_by_handle_at syscall are collected.
If the auditd daemon is configured to use the augenrules
program to read audit rules during daemon startup (the default), add the
rules below to a file with suffix .rules in the directory
/etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the rules below to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S open_by_handle_at -F a2&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b32 -S open_by_handle_at -F a2&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-createIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S open_by_handle_at -F a2&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b64 -S open_by_handle_at -F a2&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-create |
Unsuccessful attempts to access files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Events that Modify the System's Discretionary Access Controls - chmod |
At a minimum, the audit system should collect file permission
changes for all users and root. If the auditd daemon is configured to
use the augenrules program to read audit rules during daemon startup
(the default), add the following line to a file with suffix .rules in
the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S chmod -F auid>=1000 -F auid!=unset -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S chmod -F auid>=1000 -F auid!=unset -F key=perm_modIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S chmod -F auid>=1000 -F auid!=unset -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S chmod -F auid>=1000 -F auid!=unset -F key=perm_mod |
The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Any Attempts to Run restorecon |
At a minimum, the audit system should collect any execution attempt
of the restorecon command for all users and root. If the auditd
daemon is configured to use the augenrules program to read audit rules
during daemon startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/sbin/restorecon -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F path=/usr/sbin/restorecon -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AU-2(a) | Configure auditing of unsuccessful file deletions (ppc64le) |
Ensure that unsuccessful attempts to delete a file are audited.
The following rules configure audit as described above:
## Unsuccessful file delete -a always,exit -F arch=b64 -S unlink,unlinkat,rename,renameat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete -a always,exit -F arch=b64 -S unlink,unlinkat,rename,renameat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-deleteLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Unsuccessful attempts to delete a file might be signs of malicious activities. Auditing of such events help in monitoring and investigating of such activities. |
| AU-2(a) | Configure auditing of unsuccessful file accesses (AArch64) |
Ensure that unsuccessful attempts to access a file are audited.
The following rules configure audit as described above:
## Unsuccessful file access (any other opens) This has to go last. -a always,exit -F arch=b32 -S open,openat,openat2,open_by_handle_at -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-access -a always,exit -F arch=b64 -S openat,openat2,open_by_handle_at -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-access -a always,exit -F arch=b32 -S open,openat,openat2,open_by_handle_at -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-access -a always,exit -F arch=b64 -S openat,openat2,open_by_handle_at -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-accessLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Unsuccessful attempts to access a file might be signs of malicious activity happening within the system. Auditing of such activities helps in their monitoring and investigation. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Attempts to Alter Logon and Logout Events - faillock |
The audit system already collects login information for all users
and root. If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following lines to a file with suffix .rules in the
directory /etc/audit/rules.d in order to watch for attempted manual
edits of files involved in storing logon events:
-w /var/log/faillock -p wa -k loginsIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file in order to watch for unattempted manual edits of files involved in storing logon events: -w /var/log/faillock -p wa -k logins |
Manual editing of these files may indicate nefarious activity, such as an attacker attempting to remove evidence of an intrusion. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Attempts to Alter Logon and Logout Events |
The audit system already collects login information for all users
and root. If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following lines to a file with suffix .rules in the
directory /etc/audit/rules.d in order to watch for attempted manual
edits of files involved in storing logon events:
-w /var/log/tallylog -p wa -k logins -w /var/log/faillock -p wa -k logins -w /var/log/lastlog -p wa -k loginsIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file in order to watch for unattempted manual edits of files involved in storing logon events: -w /var/log/tallylog -p wa -k logins -w /var/log/faillock -p wa -k logins -w /var/log/lastlog -p wa -k logins |
Manual editing of these files may indicate nefarious activity, such as an attacker attempting to remove evidence of an intrusion. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Access Attempts to Files - creat |
At a minimum, the audit system should collect unauthorized file
accesses for all users and root. If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S creat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b32 -S creat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S creat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b64 -S creat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S creat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b32 -S creat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S creat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b64 -S creat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=access |
Unsuccessful attempts to access files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Ownership Changes to Files - chown |
The audit system should collect unsuccessful file ownership change
attempts for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the following lines to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S chown -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b32 -S chown -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-changeIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S chown -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b64 -S chown -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change |
Unsuccessful attempts to change ownership of files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(a) | Configure auditing of unsuccessful file creations |
Ensure that unsuccessful attempts to create a file are audited.
The following rules configure audit as described above:
## Unsuccessful file creation (open with O_CREAT) -a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b32 -S open -F a1&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b64 -S open -F a1&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b32 -S creat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b64 -S creat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b32 -S open -F a1&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b64 -S open -F a1&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b32 -S creat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b64 -S creat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-createLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Unsuccessful file creations might be a sign of a malicious action being performed on the system. Keeping log of such events helps in monitoring and investigation of such actions. |
| AU-2(a) | Configure auditing of successful ownership changes (ppc64le) |
Ensure that successful attempts to change an ownership of files or directories are audited.
The following rules configure audit as described above:
## Successful ownership change -a always,exit -F arch=b64 -S lchown,fchown,chown,fchownat -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-owner-changeLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing of successful ownership changes of files or directories helps in monitoring or investingating of activities performed on the system. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Events that Modify the System's Mandatory Access Controls in usr/share |
If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following line to a file with suffix .rules in the
directory /etc/audit/rules.d:
-w /usr/share/selinux/ -p wa -k MAC-policyIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -w /usr/share/selinux/ -p wa -k MAC-policy |
The system's mandatory access policy (SELinux) should not be arbitrarily changed by anything other than administrator action. All changes to MAC policy should be audited. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify the System's Network Environment |
If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following lines to a file with suffix .rules in the
directory /etc/audit/rules.d, setting ARCH to either b32 or b64 as
appropriate for your system:
-a always,exit -F arch=ARCH -S sethostname,setdomainname -F key=audit_rules_networkconfig_modification -w /etc/issue -p wa -k audit_rules_networkconfig_modification -w /etc/issue.net -p wa -k audit_rules_networkconfig_modification -w /etc/hosts -p wa -k audit_rules_networkconfig_modification -w /etc/sysconfig/network -p wa -k audit_rules_networkconfig_modificationIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file, setting ARCH to either b32 or b64 as appropriate for your system: -a always,exit -F arch=ARCH -S sethostname,setdomainname -F key=audit_rules_networkconfig_modification -w /etc/issue -p wa -k audit_rules_networkconfig_modification -w /etc/issue.net -p wa -k audit_rules_networkconfig_modification -w /etc/hosts -p wa -k audit_rules_networkconfig_modification -w /etc/sysconfig/network -p wa -k audit_rules_networkconfig_modification |
The network environment should not be modified by anything other than administrator action. Any change to network parameters should be audited. |
| AU-2(a) | Configure auditing of successful file modifications (ppc64le) |
Ensure that successful attempts to modify a file are audited.
The following rules configure audit as described above:
## Successful file modifications (open for write or truncate) -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&01003 -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-modification -a always,exit -F arch=b64 -S open -F a1&01003 -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-modification -a always,exit -F arch=b64 -S truncate,ftruncate -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-modificationLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing of successful attempts to modify a file helps in investigation of actions which happened on the system. |
| AU-2(a) | Configure auditing of successful file accesses (ppc64le) |
Ensure that successful attempts to access a file are audited.
The following rules configure audit as described above:
## Successful file access (any other opens) This has to go last. ## These next two are likely to result in a whole lot of events -a always,exit -F arch=b64 -S open,openat,openat2,open_by_handle_at -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-accessLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing of successful attempts to access a file helps in investigation of activities performed on the system. |
| AU-2(a) | Perform general configuration of Audit for OSPP |
Configure some basic Audit parameters specific for OSPP profile.
In particular, configure Audit to watch for direct modification of files storing system user and group information, and usage of applications with special rights which can change system configuration.
Further audited events include access to audit log it self, attempts to Alter Process and Session Initiation Information, and attempts to modify MAC controls.
The following rules configure audit as described above:
## The purpose of these rules is to meet the requirements for Operating ## System Protection Profile (OSPP)v4.2. These rules depends on having ## the following rule files copied to /etc/audit/rules.d: ## ## 10-base-config.rules, 11-loginuid.rules, ## 30-ospp-v42-1-create-failed.rules, 30-ospp-v42-1-create-success.rules, ## 30-ospp-v42-2-modify-failed.rules, 30-ospp-v42-2-modify-success.rules, ## 30-ospp-v42-3-access-failed.rules, 30-ospp-v42-3-access-success.rules, ## 30-ospp-v42-4-delete-failed.rules, 30-ospp-v42-4-delete-success.rules, ## 30-ospp-v42-5-perm-change-failed.rules, ## 30-ospp-v42-5-perm-change-success.rules, ## 30-ospp-v42-6-owner-change-failed.rules, ## 30-ospp-v42-6-owner-change-success.rules ## ## original copies may be found in /usr/share/audit/sample-rules/ ## User add delete modify. This is covered by pam. However, someone could ## open a file and directly create or modify a user, so we'll watch passwd and ## shadow for writes -a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&03 -F path=/etc/passwd -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&03 -F path=/etc/passwd -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b32 -S open -F a1&03 -F path=/etc/passwd -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b64 -S open -F a1&03 -F path=/etc/passwd -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&03 -F path=/etc/shadow -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&03 -F path=/etc/shadow -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b32 -S open -F a1&03 -F path=/etc/shadow -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b64 -S open -F a1&03 -F path=/etc/shadow -F auid>=1000 -F auid!=unset -F key=user-modify ## User enable and disable. This is entirely handled by pam. ## Group add delete modify. This is covered by pam. However, someone could ## open a file and directly create or modify a user, so we'll watch group and ## gshadow for writes -a always,exit -F arch=b32 -F path=/etc/passwd -F perm=wa -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b64 -F path=/etc/passwd -F perm=wa -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b32 -F path=/etc/shadow -F perm=wa -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b64 -F path=/etc/shadow -F perm=wa -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b32 -F path=/etc/group -F perm=wa -F auid>=1000 -F auid!=unset -F key=group-modify -a always,exit -F arch=b64 -F path=/etc/group -F perm=wa -F auid>=1000 -F auid!=unset -F key=group-modify -a always,exit -F arch=b32 -F path=/etc/gshadow -F perm=wa -F auid>=1000 -F auid!=unset -F key=group-modify -a always,exit -F arch=b64 -F path=/etc/gshadow -F perm=wa -F auid>=1000 -F auid!=unset -F key=group-modify ## Use of special rights for config changes. This would be use of setuid ## programs that relate to user accts. This is not all setuid apps because ## requirements are only for ones that affect system configuration. -a always,exit -F arch=b32 -F path=/usr/sbin/unix_chkpwd -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/sbin/unix_chkpwd -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/sbin/usernetctl -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/sbin/usernetctl -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/sbin/userhelper -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/sbin/userhelper -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/sbin/seunshare -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/sbin/seunshare -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/mount -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/mount -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/newgrp -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/newgrp -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/newuidmap -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/newuidmap -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/gpasswd -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/gpasswd -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/newgidmap -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/newgidmap -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/umount -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/umount -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/passwd -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/passwd -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/crontab -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/crontab -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/at -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/at -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/sbin/grub2-set-bootflag -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/sbin/grub2-set-bootflag -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes ## Privilege escalation via su or sudo. This is entirely handled by pam. ## Special case for systemd-run. It is not audit aware, specifically watch it -a always,exit -F arch=b32 -F path=/usr/bin/systemd-run -F perm=x -F auid!=unset -F key=maybe-escalation -a always,exit -F arch=b64 -F path=/usr/bin/systemd-run -F perm=x -F auid!=unset -F key=maybe-escalation ## Special case for pkexec. It is not audit aware, specifically watch it -a always,exit -F arch=b32 -F path=/usr/bin/pkexec -F perm=x -F key=maybe-escalation -a always,exit -F arch=b64 -F path=/usr/bin/pkexec -F perm=x -F key=maybe-escalation ## Watch for configuration changes to privilege escalation. -a always,exit -F arch=b32 -F path=/etc/sudoers -F perm=wa -F key=special-config-changes -a always,exit -F arch=b64 -F path=/etc/sudoers -F perm=wa -F key=special-config-changes -a always,exit -F arch=b32 -F dir=/etc/sudoers.d/ -F perm=wa -F key=special-config-changes -a always,exit -F arch=b64 -F dir=/etc/sudoers.d/ -F perm=wa -F key=special-config-changes ## Audit log access -a always,exit -F arch=b32 -F dir=/var/log/audit/ -F perm=r -F auid>=1000 -F auid!=unset -F key=access-audit-trail -a always,exit -F arch=b64 -F dir=/var/log/audit/ -F perm=r -F auid>=1000 -F auid!=unset -F key=access-audit-trail ## Attempts to Alter Process and Session Initiation Information -a always,exit -F arch=b32 -F path=/var/run/utmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session -a always,exit -F arch=b64 -F path=/var/run/utmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session -a always,exit -F arch=b32 -F path=/var/log/btmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session -a always,exit -F arch=b64 -F path=/var/log/btmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session -a always,exit -F arch=b32 -F path=/var/log/wtmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session -a always,exit -F arch=b64 -F path=/var/log/wtmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session ## Attempts to modify MAC controls -a always,exit -F arch=b32 -F dir=/etc/selinux/ -F perm=wa -F auid>=1000 -F auid!=unset -F key=MAC-policy -a always,exit -F arch=b64 -F dir=/etc/selinux/ -F perm=wa -F auid>=1000 -F auid!=unset -F key=MAC-policy ## Software updates. This is entirely handled by rpm. ## System start and shutdown. This is entirely handled by systemd ## Kernel Module loading. This is handled in 43-module-load.rules ## Application invocation. The requirements list an optional requirement ## FPT_SRP_EXT.1 Software Restriction Policies. This event is intended to ## state results from that policy. This would be handled entirely by ## that daemon.Load new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing of events listed in the description provides data for monitoring and investigation of potentially malicious events e.g. tampering with Audit logs, malicious access to files storing information about system users and groups etc. |
| AU-2(a) | Configure auditing of successful permission changes (ppc64le) |
Ensure that successful attempts to modify permissions of files or directories are audited.
The following rules configure audit as described above:
## Successful permission change -a always,exit -F arch=b64 -S chmod,fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-perm-changeLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing successful file or directory permission changes helps in monitoring and investigating of activities performed on the system. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Events that Modify the System's Discretionary Access Controls - fchown |
At a minimum, the audit system should collect file permission
changes for all users and root. If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following line to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S fchown -F auid>=1000 -F auid!=unset -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S fchown -F auid>=1000 -F auid!=unset -F key=perm_modIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S fchown -F auid>=1000 -F auid!=unset -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S fchown -F auid>=1000 -F auid!=unset -F key=perm_mod |
The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users. |
| AU-2(a) | Configure auditing of unsuccessful permission changes (ppc64le) |
Ensure that unsuccessful attempts to change file or directory permissions are audited.
The following rules configure audit as described above:
## Unsuccessful permission change -a always,exit -F arch=b64 -S chmod,fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-perm-change -a always,exit -F arch=b64 -S chmod,fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-perm-changeLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Unsuccessful attempts to change permissions of files or directories might be signs of malicious activity. Having such events audited helps in monitoring and investigation of such activities. |
| AU-2(d) AU-12(c) CM-6(a) |
Ensure auditd Rules For Unauthorized Attempts To open Are Ordered Correctly |
The audit system should collect detailed unauthorized file
accesses for all users and root.
To correctly identify unsuccessful creation, unsuccessful modification and unsuccessful access
of files via open syscall the audit rules collecting these events need to be in certain order.
The more specific rules need to come before the less specific rules. The reason for that is that more
specific rules cover a subset of events covered in the less specific rules, thus, they need to come
before to not be overshadowed by less specific rules, which match a bigger set of events.
Make sure that rules for unsuccessful calls of open syscall are in the order shown below.
If the auditd daemon is configured to use the augenrules
program to read audit rules during daemon startup (the default), check the order of
rules below in a file with suffix .rules in the directory
/etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, check the order of rules below in
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S open -F a1&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b32 -S open -F a1&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b32 -S open -F a1&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b32 -S open -F a1&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b32 -S open -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-access -a always,exit -F arch=b32 -S open -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-accessIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S open -F a1&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b64 -S open -F a1&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b64 -S open -F a1&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b64 -S open -F a1&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b64 -S open -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-access -a always,exit -F arch=b64 -S open -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-access |
The more specific rules cover a subset of events covered by the less specific rules. By ordering them from more specific to less specific, it is assured that the less specific rule will not catch events better recorded by the more specific rule. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Events that Modify the System's Discretionary Access Controls - setxattr |
At a minimum, the audit system should collect file permission
changes for all users and root. If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following line to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S setxattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b32 -S setxattr -F auid=0 -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S setxattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b64 -S setxattr -F auid=0 -F key=perm_modIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S setxattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b32 -S setxattr -F auid=0 -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S setxattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b64 -S setxattr -F auid=0 -F key=perm_mod |
The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Ownership Changes to Files - lchown |
The audit system should collect unsuccessful file ownership change
attempts for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the following lines to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S lchown -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b32 -S lchown -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-changeIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S lchown -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b64 -S lchown -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change |
Unsuccessful attempts to change ownership of files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(a) | Configure auditing of successful ownership changes |
Ensure that successful attempts to change an ownership of files or directories are audited.
The following rules configure audit as described above:
## Successful ownership change -a always,exit -F arch=b32 -S lchown,fchown,chown,fchownat -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-owner-change -a always,exit -F arch=b64 -S lchown,fchown,chown,fchownat -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-owner-changeLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing of successful ownership changes of files or directories helps in monitoring or investingating of activities performed on the system. |
| AU-2(a) | Configure auditing of unsuccessful permission changes (AArch64) |
Ensure that unsuccessful attempts to change file or directory permissions are audited.
The following rules configure audit as described above:
## Unsuccessful permission change -a always,exit -F arch=b32 -S chmod,fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-perm-change -a always,exit -F arch=b64 -S fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-perm-change -a always,exit -F arch=b32 -S chmod,fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-perm-change -a always,exit -F arch=b64 -S fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-perm-changeLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Unsuccessful attempts to change permissions of files or directories might be signs of malicious activity. Having such events audited helps in monitoring and investigation of such activities. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on Kernel Module Loading and Unloading |
To capture kernel module loading and unloading events, use following lines, setting ARCH to
either b32 for 32-bit system, or having two lines for both b32 and b64 in case your system is 64-bit:
-a always,exit -F arch=ARCH -S init_module,finit_module,delete_module -F auid>=1000 -F auid!=unset -F key=modulesThe place to add the lines depends on a way auditd daemon is configured. If it is configured to use the augenrules program (the default), add the lines to a file with suffix .rules in the directory /etc/audit/rules.d. If the auditd daemon is configured to use the auditctl utility, add the lines to file /etc/audit/audit.rules. |
The addition/removal of kernel modules can be used to alter the behavior of the kernel and potentially introduce malicious code into kernel space. It is important to have an audit trail of modules that have been introduced into the kernel. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Permission Changes to Files - fsetxattr |
The audit system should collect unsuccessful file permission change
attempts for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the following lines to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S fsetxattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b32 -S fsetxattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-changeIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S fsetxattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b64 -S fsetxattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change |
Unsuccessful attempts to change permissions of files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - mount |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/bin/mount -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/bin/mount -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Modification Attempts to Files - open O_TRUNC_WRITE |
The audit system should collect detailed unauthorized file accesses for
all users and root. The open syscall can be used to modify files
if called for write operation of with O_TRUNC_WRITE flag.
The following auidt rules will asure that unsuccessful attempts to modify a
file via open syscall are collected.
If the auditd daemon is configured to use the augenrules
program to read audit rules during daemon startup (the default), add the
rules below to a file with suffix .rules in the directory
/etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the rules below to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S open -F a1&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b32 -S open -F a1&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modificationIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S open -F a1&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b64 -S open -F a1&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification |
Unsuccessful attempts to access files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Attempts to Alter Process and Session Initiation Information |
The audit system already collects process information for all
users and root. If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following lines to a file with suffix .rules in the
directory /etc/audit/rules.d in order to watch for attempted manual
edits of files involved in storing such process information:
-w /var/run/utmp -p wa -k session -w /var/log/btmp -p wa -k session -w /var/log/wtmp -p wa -k sessionIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file in order to watch for attempted manual edits of files involved in storing such process information: -w /var/run/utmp -p wa -k session -w /var/log/btmp -p wa -k session -w /var/log/wtmp -p wa -k session |
Manual editing of these files may indicate nefarious activity, such as an attacker attempting to remove evidence of an intrusion. |
| AU-2(a) | Configure auditing of unsuccessful permission changes |
Ensure that unsuccessful attempts to change file or directory permissions are audited.
The following rules configure audit as described above:
## Unsuccessful permission change -a always,exit -F arch=b32 -S chmod,fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-perm-change -a always,exit -F arch=b64 -S chmod,fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-perm-change -a always,exit -F arch=b32 -S chmod,fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-perm-change -a always,exit -F arch=b64 -S chmod,fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-perm-changeLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Unsuccessful attempts to change permissions of files or directories might be signs of malicious activity. Having such events audited helps in monitoring and investigation of such activities. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Any Attempts to Run seunshare |
At a minimum, the audit system should collect any execution attempt
of the seunshare command for all users and root. If the auditd
daemon is configured to use the augenrules program to read audit rules
during daemon startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/sbin/seunshare -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F path=/usr/sbin/seunshare -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AU-2(a) | Configure auditing of unsuccessful file modifications |
Ensure that unsuccessful attempts to modify a file are audited.
The following rules configure audit as described above:
## Unsuccessful file modifications (open for write or truncate) -a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b32 -S open -F a1&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b64 -S open -F a1&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b32 -S truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b64 -S truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b32 -S open -F a1&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b64 -S open -F a1&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b32 -S truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b64 -S truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-modificationLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Unsuccessful file modifications might be a sign of a malicious action being performed on the system. Auditing of such events helps in detection and investigation of such actions. |
| AU-2(d) AU-12(c) CM-6(a) |
Ensure auditd Unauthorized Access Attempts To open_by_handle_at Are Ordered Correctly |
The audit system should collect detailed unauthorized file
accesses for all users and root.
To correctly identify unsuccessful creation, unsuccessful modification and unsuccessful access
of files via open_by_handle_at syscall the audit rules collecting these events need to be in certain order.
The more specific rules need to come before the less specific rules. The reason for that is that more
specific rules cover a subset of events covered in the less specific rules, thus, they need to come
before to not be overshadowed by less specific rules, which match a bigger set of events.
Make sure that rules for unsuccessful calls of open_by_handle_at syscall are in the order shown below.
If the auditd daemon is configured to use the augenrules
program to read audit rules during daemon startup (the default), check the order of
rules below in a file with suffix .rules in the directory
/etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, check the order of rules below in
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S open_by_handle_at -F a2&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b32 -S open_by_handle_at -F a2&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b32 -S open_by_handle_at -F a2&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b32 -S open_by_handle_at -F a2&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b32 -S open_by_handle_at -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-access -a always,exit -F arch=b32 -S open_by_handle_at -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-accessIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S open_by_handle_at -F a2&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b64 -S open_by_handle_at -F a2&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b64 -S open_by_handle_at -F a2&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b64 -S open_by_handle_at -F a2&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b64 -S open_by_handle_at -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-access -a always,exit -F arch=b64 -S open_by_handle_at -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-access |
The more specific rules cover a subset of events covered by the less specific rules. By ordering them from more specific to less specific, it is assured that the less specific rule will not catch events better recorded by the more specific rule. |
| AU-2(a) | Configure auditing of successful file creations (AArch64) |
Ensure that successful attempts to create a file are audited.
The following rules configure audit as described above:
## Successful file creation (open with O_CREAT) -a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&0100 -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-create -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&0100 -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-create -a always,exit -F arch=b32 -S open -F a1&0100 -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-create -a always,exit -F arch=b32 -S creat -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-createLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing of successful attempts to create a file helps in investigation of actions which happened on the system. |
| AU-2(d) AU-12(c) CM-6(a) |
Ensure auditd Collects File Deletion Events by User - unlinkat |
At a minimum, the audit system should collect file deletion events
for all users and root. If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following line to a file with suffix .rules in the
directory /etc/audit/rules.d, setting ARCH to either b32 or b64 as
appropriate for your system:
-a always,exit -F arch=ARCH -S unlinkat -F auid>=1000 -F auid!=unset -F key=deleteIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file, setting ARCH to either b32 or b64 as appropriate for your system: -a always,exit -F arch=ARCH -S unlinkat -F auid>=1000 -F auid!=unset -F key=delete |
Auditing file deletions will create an audit trail for files that are removed from the system. The audit trail could aid in system troubleshooting, as well as, detecting malicious processes that attempt to delete log files to conceal their presence. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Attempts to Alter Logon and Logout Events - tallylog |
The audit system already collects login information for all users
and root. If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following lines to a file with suffix .rules in the
directory /etc/audit/rules.d in order to watch for attempted manual
edits of files involved in storing logon events:
-w /var/log/tallylog -p wa -k loginsIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file in order to watch for unattempted manual edits of files involved in storing logon events: -w /var/log/tallylog -p wa -k logins |
Manual editing of these files may indicate nefarious activity, such as an attacker attempting to remove evidence of an intrusion. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Attempts to Alter the localtime File |
If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the default),
add the following line to a file with suffix .rules in the directory
/etc/audit/rules.d:
-w /etc/localtime -p wa -k audit_time_rulesIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -w /etc/localtime -p wa -k audit_time_rulesThe -k option allows for the specification of a key in string form that can be used for better reporting capability through ausearch and aureport and should always be used. |
Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - umount |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/bin/umount -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/bin/umount -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| IA-2 AC-3 CM-6(a) |
Require Authentication for Emergency Systemd Target |
Emergency mode is intended as a system recovery
method, providing a single user root access to the system
during a failed boot sequence.
By default, Emergency mode is protected by requiring a password and is set in /usr/lib/systemd/system/emergency.service. |
This prevents attackers with physical access from trivially bypassing security on the machine and gaining root access. Such accesses are further prevented by configuring the bootloader password. |
| AU-2(a) | Configure auditing of unsuccessful file accesses (ppc64le) |
Ensure that unsuccessful attempts to access a file are audited.
The following rules configure audit as described above:
## Unsuccessful file access (any other opens) This has to go last. -a always,exit -F arch=b64 -S open,openat,openat2,open_by_handle_at -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-access -a always,exit -F arch=b64 -S open,openat,openat2,open_by_handle_at -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-accessLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Unsuccessful attempts to access a file might be signs of malicious activity happening within the system. Auditing of such activities helps in their monitoring and investigation. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Any Attempts to Run setsebool |
At a minimum, the audit system should collect any execution attempt
of the setsebool command for all users and root. If the auditd
daemon is configured to use the augenrules program to read audit rules
during daemon startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/sbin/setsebool -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F path=/usr/sbin/setsebool -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AU-2(a) | Configure auditing of successful file deletions (ppc64le) |
Ensure that successful attempts to delete a file are audited.
The following rules configure audit as described above:
## Successful file delete -a always,exit -F arch=b64 -S unlink,unlinkat,rename,renameat -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-deleteLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing of successful attempts to delete a file may help in monitoring and investigation of activities performed on the system. |
| AU-2(a) | Configure auditing of successful file deletions |
Ensure that successful attempts to delete a file are audited.
The following rules configure audit as described above:
## Successful file delete -a always,exit -F arch=b32 -S unlink,unlinkat,rename,renameat -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-delete -a always,exit -F arch=b64 -S unlink,unlinkat,rename,renameat -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-deleteLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing of successful attempts to delete a file may help in monitoring and investigation of activities performed on the system. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Permission Changes to Files - fchmod |
The audit system should collect unsuccessful file permission change
attempts for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the following lines to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S fchmod -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b32 -S fchmod -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-changeIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S fchmod -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b64 -S fchmod -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change |
Unsuccessful attempts to change permissions of files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) CM-6(a) |
Ensure auditd Collects Unauthorized Access Attempts to Files (unsuccessful) |
At a minimum the audit system should collect unauthorized file
accesses for all users and root. If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b32 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b64 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b32 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b64 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=access |
Unsuccessful attempts to access files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Events that Modify the System's Mandatory Access Controls |
If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following line to a file with suffix .rules in the
directory /etc/audit/rules.d:
-w /etc/selinux/ -p wa -k MAC-policyIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -w /etc/selinux/ -p wa -k MAC-policy |
The system's mandatory access policy (SELinux) should not be arbitrarily changed by anything other than administrator action. All changes to MAC policy should be audited. |
| AU-2(a) | Perform general configuration of Audit for OSPP (ppc64le) |
Configure some basic Audit parameters specific for OSPP profile.
In particular, configure Audit to watch for direct modification of files storing system user and group information, and usage of applications with special rights which can change system configuration.
Further audited events include access to audit log it self, attempts to Alter Process and Session Initiation Information, and attempts to modify MAC controls.
The following rules configure audit as described above:
## The purpose of these rules is to meet the requirements for Operating ## System Protection Profile (OSPP)v4.2. These rules depends on having ## the following rule files copied to /etc/audit/rules.d: ## ## 10-base-config.rules, 11-loginuid.rules, ## 30-ospp-v42-1-create-failed.rules, 30-ospp-v42-1-create-success.rules, ## 30-ospp-v42-2-modify-failed.rules, 30-ospp-v42-2-modify-success.rules, ## 30-ospp-v42-3-access-failed.rules, 30-ospp-v42-3-access-success.rules, ## 30-ospp-v42-4-delete-failed.rules, 30-ospp-v42-4-delete-success.rules, ## 30-ospp-v42-5-perm-change-failed.rules, ## 30-ospp-v42-5-perm-change-success.rules, ## 30-ospp-v42-6-owner-change-failed.rules, ## 30-ospp-v42-6-owner-change-success.rules ## ## original copies may be found in /usr/share/audit/sample-rules/ ## User add delete modify. This is covered by pam. However, someone could ## open a file and directly create or modify a user, so we'll watch passwd and ## shadow for writes -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&03 -F path=/etc/passwd -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b64 -S open -F a1&03 -F path=/etc/passwd -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&03 -F path=/etc/shadow -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b64 -S open -F a1&03 -F path=/etc/shadow -F auid>=1000 -F auid!=unset -F key=user-modify ## User enable and disable. This is entirely handled by pam. ## Group add delete modify. This is covered by pam. However, someone could ## open a file and directly create or modify a user, so we'll watch group and ## gshadow for writes -a always,exit -F arch=b32 -F path=/etc/passwd -F perm=wa -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b64 -F path=/etc/passwd -F perm=wa -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b32 -F path=/etc/shadow -F perm=wa -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b64 -F path=/etc/shadow -F perm=wa -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b32 -F path=/etc/group -F perm=wa -F auid>=1000 -F auid!=unset -F key=group-modify -a always,exit -F arch=b64 -F path=/etc/group -F perm=wa -F auid>=1000 -F auid!=unset -F key=group-modify -a always,exit -F arch=b32 -F path=/etc/gshadow -F perm=wa -F auid>=1000 -F auid!=unset -F key=group-modify -a always,exit -F arch=b64 -F path=/etc/gshadow -F perm=wa -F auid>=1000 -F auid!=unset -F key=group-modify ## Use of special rights for config changes. This would be use of setuid ## programs that relate to user accts. This is not all setuid apps because ## requirements are only for ones that affect system configuration. -a always,exit -F arch=b32 -F path=/usr/sbin/unix_chkpwd -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/sbin/unix_chkpwd -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/sbin/usernetctl -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/sbin/usernetctl -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/sbin/userhelper -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/sbin/userhelper -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/sbin/seunshare -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/sbin/seunshare -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/mount -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/mount -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/newgrp -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/newgrp -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/newuidmap -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/newuidmap -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/gpasswd -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/gpasswd -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/newgidmap -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/newgidmap -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/umount -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/umount -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/passwd -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/passwd -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/crontab -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/crontab -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/at -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/at -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/sbin/grub2-set-bootflag -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/sbin/grub2-set-bootflag -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes ## Privilege escalation via su or sudo. This is entirely handled by pam. ## Special case for systemd-run. It is not audit aware, specifically watch it -a always,exit -F arch=b32 -F path=/usr/bin/systemd-run -F perm=x -F auid!=unset -F key=maybe-escalation -a always,exit -F arch=b64 -F path=/usr/bin/systemd-run -F perm=x -F auid!=unset -F key=maybe-escalation ## Special case for pkexec. It is not audit aware, specifically watch it -a always,exit -F arch=b32 -F path=/usr/bin/pkexec -F perm=x -F key=maybe-escalation -a always,exit -F arch=b64 -F path=/usr/bin/pkexec -F perm=x -F key=maybe-escalation ## Watch for configuration changes to privilege escalation. -a always,exit -F arch=b32 -F path=/etc/sudoers -F perm=wa -F key=special-config-changes -a always,exit -F arch=b64 -F path=/etc/sudoers -F perm=wa -F key=special-config-changes -a always,exit -F arch=b32 -F dir=/etc/sudoers.d/ -F perm=wa -F key=special-config-changes -a always,exit -F arch=b64 -F dir=/etc/sudoers.d/ -F perm=wa -F key=special-config-changes ## Audit log access -a always,exit -F arch=b32 -F dir=/var/log/audit/ -F perm=r -F auid>=1000 -F auid!=unset -F key=access-audit-trail -a always,exit -F arch=b64 -F dir=/var/log/audit/ -F perm=r -F auid>=1000 -F auid!=unset -F key=access-audit-trail ## Attempts to Alter Process and Session Initiation Information -a always,exit -F arch=b32 -F path=/var/run/utmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session -a always,exit -F arch=b64 -F path=/var/run/utmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session -a always,exit -F arch=b32 -F path=/var/log/btmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session -a always,exit -F arch=b64 -F path=/var/log/btmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session -a always,exit -F arch=b32 -F path=/var/log/wtmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session -a always,exit -F arch=b64 -F path=/var/log/wtmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session ## Attempts to modify MAC controls -a always,exit -F arch=b32 -F dir=/etc/selinux/ -F perm=wa -F auid>=1000 -F auid!=unset -F key=MAC-policy -a always,exit -F arch=b64 -F dir=/etc/selinux/ -F perm=wa -F auid>=1000 -F auid!=unset -F key=MAC-policy ## Software updates. This is entirely handled by rpm. ## System start and shutdown. This is entirely handled by systemd ## Kernel Module loading. This is handled in 43-module-load.rules ## Application invocation. The requirements list an optional requirement ## FPT_SRP_EXT.1 Software Restriction Policies. This event is intended to ## state results from that policy. This would be handled entirely by ## that daemon.Load new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing of events listed in the description provides data for monitoring and investigation of potentially malicious events e.g. tampering with Audit logs, malicious access to files storing information about system users and groups etc. |
| AU-2(a) | Configure auditing of unsuccessful ownership changes (AArch64) |
Ensure that unsuccessful attempts to change an ownership of files or directories are audited.
The following rules configure audit as described above:
## Unsuccessful ownership change -a always,exit -F arch=b32 -S lchown,fchown,chown,fchownat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-owner-change -a always,exit -F arch=b64 -S fchown,fchownat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-owner-change -a always,exit -F arch=b32 -S lchown,fchown,chown,fchownat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-owner-change -a always,exit -F arch=b64 -S fchown,fchownat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-owner-changeLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Unsuccessful attempts to change an ownership of files or directories might be signs of a malicious activity. Having such events audited helps in monitoring and investigation of such activities. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Delete Attempts to Files - unlink |
The audit system should collect unsuccessful file deletion
attempts for all users and root. If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the following lines to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S unlink -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete -a always,exit -F arch=b32 -S unlink -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-deleteIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S unlink -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete -a always,exit -F arch=b64 -S unlink -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete |
Unsuccessful attempts to delete files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Permission Changes to Files - setxattr |
The audit system should collect unsuccessful file permission change
attempts for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the following lines to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S setxattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b32 -S setxattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-changeIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S setxattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b64 -S setxattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change |
Unsuccessful attempts to change permissions of files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(a) | Configure auditing of unsuccessful file modifications (AARch64) |
Ensure that unsuccessful attempts to modify a file are audited.
The following rules configure audit as described above:
## Unsuccessful file modifications (open for write or truncate) -a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b32 -S open -F a1&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b32 -S truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b64 -S truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b32 -S open -F a1&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b32 -S truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b64 -S truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-modificationLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Unsuccessful file modifications might be a sign of a malicious action being performed on the system. Auditing of such events helps in detection and investigation of such actions. |
| AU-2(a) | Configure auditing of unsuccessful ownership changes (ppc64le) |
Ensure that unsuccessful attempts to change an ownership of files or directories are audited.
The following rules configure audit as described above:
## Unsuccessful ownership change -a always,exit -F arch=b64 -S lchown,fchown,chown,fchownat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-owner-change -a always,exit -F arch=b64 -S lchown,fchown,chown,fchownat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-owner-changeLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Unsuccessful attempts to change an ownership of files or directories might be signs of a malicious activity. Having such events audited helps in monitoring and investigation of such activities. |
| IA-2 CM-6(a) |
Direct root Logins Not Allowed |
To further limit access to the root account, administrators
can disable root logins at the console by editing the /etc/securetty file.
This file lists all devices the root user is allowed to login to. If the file does
not exist at all, the root user can login through any communication device on the
system, whether via the console or via a raw network interface. This is dangerous
as user can login to the system as root via Telnet, which sends the password in
plain text over the network. By default, Red Hat Enterprise Linux 8's
/etc/securetty file only allows the root user to login at the console
physically attached to the system. To prevent root from logging in, remove the
contents of this file. To prevent direct root logins, remove the contents of this
file by typing the following command:
$ sudo echo > /etc/securetty |
Disabling direct root logins ensures proper accountability and multifactor authentication to privileged accounts. Users will first login, then escalate to privileged (root) access via su / sudo. This is required for FISMA Low and FISMA Moderate systems. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Events that Modify the System's Discretionary Access Controls - fchownat |
At a minimum, the audit system should collect file permission
changes for all users and root. If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following line to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S fchownat -F auid>=1000 -F auid!=unset -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S fchownat -F auid>=1000 -F auid!=unset -F key=perm_modIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S fchownat -F auid>=1000 -F auid!=unset -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S fchownat -F auid>=1000 -F auid!=unset -F key=perm_mod |
The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - sudo |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/bin/sudo -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/bin/sudo -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AU-2(a) | Configure immutable Audit login UIDs |
Configure kernel to prevent modification of login UIDs once they are set.
Changing login UIDs while this configuration is enforced requires special capabilities which
are not available to unprivileged users.
The following rules configure audit as described above:
## Make the loginuid immutable. This prevents tampering with the auid. --loginuid-immutableLoad new Audit rules into kernel by running: augenrules --load |
If modification of login UIDs is not prevented, they can be changed by unprivileged users and make auditing complicated or impossible. |
| AU-2(a) | Configure auditing of successful file creations |
Ensure that successful attempts to create a file are audited.
The following rules configure audit as described above:
## Successful file creation (open with O_CREAT) -a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&0100 -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-create -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&0100 -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-create -a always,exit -F arch=b32 -S open -F a1&0100 -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-create -a always,exit -F arch=b64 -S open -F a1&0100 -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-create -a always,exit -F arch=b32 -S creat -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-create -a always,exit -F arch=b64 -S creat -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-createLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing of successful attempts to create a file helps in investigation of actions which happened on the system. |
| AU-2(a) | Configure basic parameters of Audit system |
Perform basic configuration of Audit system.
Make sure that any previously defined rules are cleared, the auditing system is configured to handle sudden bursts of events, and in cases of failure, messages are configured to be directed to system log.
The following rules configure audit as described above:
## First rule - delete all -D ## Increase the buffers to survive stress events. ## Make this bigger for busy systems -b 8192 ## This determine how long to wait in burst of events --backlog_wait_time 60000 ## Set failure mode to syslog -f 1Load new Audit rules into kernel by running: augenrules --load |
Without basic configurations, audit may not perform as expected. It may not be able to correctly handle events under stressful conditions, or log events in case of failure. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Events that Modify the System's Discretionary Access Controls - chown |
At a minimum, the audit system should collect file permission
changes for all users and root. If the auditd daemon is configured to
use the augenrules program to read audit rules during daemon startup
(the default), add the following line to a file with suffix .rules in
the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S chown -F auid>=1000 -F auid!=unset -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S chown -F auid>=1000 -F auid!=unset -F key=perm_modIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S chown -F auid>=1000 -F auid!=unset -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S chown -F auid>=1000 -F auid!=unset -F key=perm_mod |
The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on Kernel Module Loading and Unloading - finit_module |
If the auditd daemon is configured to use the augenrules program
to read audit rules during daemon startup (the default), add the following lines to a file
with suffix .rules in the directory /etc/audit/rules.d to capture kernel module
loading and unloading events, setting ARCH to either b32 or b64 as appropriate for your system:
-a always,exit -F arch=ARCH -S finit_module -F auid>=1000 -F auid!=unset -F key=modulesIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file in order to capture kernel module loading and unloading events, setting ARCH to either b32 or b64 as appropriate for your system: -a always,exit -F arch=ARCH -S finit_module -F auid>=1000 -F auid!=unset -F key=modules |
The addition/removal of kernel modules can be used to alter the behavior of the kernel and potentially introduce malicious code into kernel space. It is important to have an audit trail of modules that have been introduced into the kernel. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - postdrop |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/sbin/postdrop -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/sbin/postdrop -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AU-2(a) | Configure auditing of successful file deletions (AArch64) |
Ensure that successful attempts to delete a file are audited.
The following rules configure audit as described above:
## Successful file delete -a always,exit -F arch=b32 -S unlink,unlinkat,rename,renameat -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-delete -a always,exit -F arch=b64 -S unlinkat,renameat -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-deleteLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing of successful attempts to delete a file may help in monitoring and investigation of activities performed on the system. |
| AU-2(d) AU-12(c) CM-6(a) |
Ensure auditd Collects File Deletion Events by User - renameat |
At a minimum, the audit system should collect file deletion events
for all users and root. If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following line to a file with suffix .rules in the
directory /etc/audit/rules.d, setting ARCH to either b32 or b64 as
appropriate for your system:
-a always,exit -F arch=ARCH -S renameat -F auid>=1000 -F auid!=unset -F key=deleteIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file, setting ARCH to either b32 or b64 as appropriate for your system: -a always,exit -F arch=ARCH -S renameat -F auid>=1000 -F auid!=unset -F key=delete |
Auditing file deletions will create an audit trail for files that are removed from the system. The audit trail could aid in system troubleshooting, as well as, detecting malicious processes that attempt to delete log files to conceal their presence. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Permission Changes to Files - chmod |
The audit system should collect unsuccessful file permission change
attempts for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the following lines to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S chmod -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b32 -S chmod -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-changeIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S chmod -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b64 -S chmod -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change |
Unsuccessful attempts to change permissions of files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(a) | Configure auditing of successful file modifications |
Ensure that successful attempts to modify a file are audited.
The following rules configure audit as described above:
## Successful file modifications (open for write or truncate) -a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&01003 -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-modification -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&01003 -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-modification -a always,exit -F arch=b32 -S open -F a1&01003 -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-modification -a always,exit -F arch=b64 -S open -F a1&01003 -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-modification -a always,exit -F arch=b32 -S truncate,ftruncate -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-modification -a always,exit -F arch=b64 -S truncate,ftruncate -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-modificationLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing of successful attempts to modify a file helps in investigation of actions which happened on the system. |
| IA-2 AC-3 CM-6(a) |
Require Authentication for Single User Mode |
Single-user mode is intended as a system recovery
method, providing a single user root access to the system by
providing a boot option at startup.
By default, single-user mode is protected by requiring a password and is set in /usr/lib/systemd/system/rescue.service. |
This prevents attackers with physical access from trivially bypassing security on the machine and gaining root access. Such accesses are further prevented by configuring the bootloader password. |
| AU-2(a) | Configure auditing of unsuccessful file deletions |
Ensure that unsuccessful attempts to delete a file are audited.
The following rules configure audit as described above:
## Unsuccessful file delete -a always,exit -F arch=b32 -S unlink,unlinkat,rename,renameat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete -a always,exit -F arch=b64 -S unlink,unlinkat,rename,renameat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete -a always,exit -F arch=b32 -S unlink,unlinkat,rename,renameat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete -a always,exit -F arch=b64 -S unlink,unlinkat,rename,renameat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-deleteLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Unsuccessful attempts to delete a file might be signs of malicious activities. Auditing of such events help in monitoring and investigating of such activities. |
| AU-2(a) | Configure auditing of successful file accesses (AArch64) |
Ensure that successful attempts to access a file are audited.
The following rules configure audit as described above:
## Successful file access (any other opens) This has to go last. ## These next two are likely to result in a whole lot of events -a always,exit -F arch=b32 -S open,openat,openat2,open_by_handle_at -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-access -a always,exit -F arch=b64 -S openat,openat2,open_by_handle_at -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-accessLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing of successful attempts to access a file helps in investigation of activities performed on the system. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Attempts to Alter Logon and Logout Events - lastlog |
The audit system already collects login information for all users
and root. If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following lines to a file with suffix .rules in the
directory /etc/audit/rules.d in order to watch for attempted manual
edits of files involved in storing logon events:
-w /var/log/lastlog -p wa -k loginsIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file in order to watch for unattempted manual edits of files involved in storing logon events: -w /var/log/lastlog -p wa -k logins |
Manual editing of these files may indicate nefarious activity, such as an attacker attempting to remove evidence of an intrusion. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on Kernel Module Unloading - delete_module |
To capture kernel module unloading events, use following line, setting ARCH to
either b32 for 32-bit system, or having two lines for both b32 and b64 in case your system is 64-bit:
-a always,exit -F arch=ARCH -S delete_module -F auid>=1000 -F auid!=unset -F key=modulesPlace to add the line depends on a way auditd daemon is configured. If it is configured to use the augenrules program (the default), add the line to a file with suffix .rules in the directory /etc/audit/rules.d. If the auditd daemon is configured to use the auditctl utility, add the line to file /etc/audit/audit.rules. |
The removal of kernel modules can be used to alter the behavior of the kernel and potentially introduce malicious code into kernel space. It is important to have an audit trail of modules that have been introduced into the kernel. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - postqueue |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/sbin/postqueue -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/sbin/postqueue -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Creation Attempts to Files - openat O_CREAT |
The audit system should collect unauthorized file accesses for
all users and root. The openat syscall can be used to create new files
when O_CREAT flag is specified.
The following auidt rules will asure that unsuccessful attempts to create a
file via openat syscall are collected.
If the auditd daemon is configured to use the augenrules
program to read audit rules during daemon startup (the default), add the
rules below to a file with suffix .rules in the directory
/etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the rules below to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S openat -F a2&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b32 -S openat -F a2&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-createIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S openat -F a2&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b64 -S openat -F a2&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-create |
Unsuccessful attempts to access files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Events that Modify the System's Discretionary Access Controls - fchmodat |
At a minimum, the audit system should collect file permission
changes for all users and root. If the auditd daemon is configured to
use the augenrules program to read audit rules during daemon startup
(the default), add the following line to a file with suffix .rules in
the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S fchmodat -F auid>=1000 -F auid!=unset -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S fchmodat -F auid>=1000 -F auid!=unset -F key=perm_modIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S fchmodat -F auid>=1000 -F auid!=unset -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S fchmodat -F auid>=1000 -F auid!=unset -F key=perm_mod |
The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users. |
| AU-2(a) | Configure auditing of successful permission changes |
Ensure that successful attempts to modify permissions of files or directories are audited.
The following rules configure audit as described above:
## Successful permission change -a always,exit -F arch=b32 -S chmod,fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-perm-change -a always,exit -F arch=b64 -S chmod,fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-perm-changeLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing successful file or directory permission changes helps in monitoring and investigating of activities performed on the system. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Events that Modify the System's Discretionary Access Controls - lremovexattr |
At a minimum, the audit system should collect file permission
changes for all users and root.
If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following line to a file with suffix .rules in the directory /etc/audit/rules.d: -a always,exit -F arch=b32 -S lremovexattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b32 -S lremovexattr -F auid=0 -F key=perm_mod If the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S lremovexattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b64 -S lremovexattr -F auid=0 -F key=perm_mod If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S lremovexattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b32 -S lremovexattr -F auid=0 -F key=perm_mod If the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S lremovexattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b64 -S lremovexattr -F auid=0 -F key=perm_mod |
The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users. |
| AU-2(a) | Configure auditing of unsuccessful ownership changes |
Ensure that unsuccessful attempts to change an ownership of files or directories are audited.
The following rules configure audit as described above:
## Unsuccessful ownership change -a always,exit -F arch=b32 -S lchown,fchown,chown,fchownat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-owner-change -a always,exit -F arch=b64 -S lchown,fchown,chown,fchownat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-owner-change -a always,exit -F arch=b32 -S lchown,fchown,chown,fchownat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-owner-change -a always,exit -F arch=b64 -S lchown,fchown,chown,fchownat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-owner-changeLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Unsuccessful attempts to change an ownership of files or directories might be signs of a malicious activity. Having such events audited helps in monitoring and investigation of such activities. |
| AU-2(a) | Configure auditing of loading and unloading of kernel modules |
Ensure that loading and unloading of kernel modules is audited.
The following rules configure audit as described above:
## These rules watch for kernel module insertion. By monitoring ## the syscall, we do not need any watches on programs. -a always,exit -F arch=b32 -S init_module,finit_module -F key=module-load -a always,exit -F arch=b64 -S init_module,finit_module -F key=module-load -a always,exit -F arch=b32 -S delete_module -F key=module-unload -a always,exit -F arch=b64 -S delete_module -F key=module-unloadLoad new Audit rules into kernel by running: augenrules --load |
Loading of a malicious kernel module introduces a risk to the system, as the module has access to sensitive data and perform actions at the operating system kernel level. Having such events audited helps in monitoring and investigating of malicious activities. |
| AU-2(a) | Perform general configuration of Audit for OSPP (AArch64) |
Configure some basic Audit parameters specific for OSPP profile.
In particular, configure Audit to watch for direct modification of files storing system user and group information, and usage of applications with special rights which can change system configuration.
Further audited events include access to audit log it self, attempts to Alter Process and Session Initiation Information, and attempts to modify MAC controls.
The following rules configure audit as described above:
## The purpose of these rules is to meet the requirements for Operating ## System Protection Profile (OSPP)v4.2. These rules depends on having ## the following rule files copied to /etc/audit/rules.d: ## ## 10-base-config.rules, 11-loginuid.rules, ## 30-ospp-v42-1-create-failed.rules, 30-ospp-v42-1-create-success.rules, ## 30-ospp-v42-2-modify-failed.rules, 30-ospp-v42-2-modify-success.rules, ## 30-ospp-v42-3-access-failed.rules, 30-ospp-v42-3-access-success.rules, ## 30-ospp-v42-4-delete-failed.rules, 30-ospp-v42-4-delete-success.rules, ## 30-ospp-v42-5-perm-change-failed.rules, ## 30-ospp-v42-5-perm-change-success.rules, ## 30-ospp-v42-6-owner-change-failed.rules, ## 30-ospp-v42-6-owner-change-success.rules ## ## original copies may be found in /usr/share/audit/sample-rules/ ## User add delete modify. This is covered by pam. However, someone could ## open a file and directly create or modify a user, so we'll watch passwd and ## shadow for writes -a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&03 -F path=/etc/passwd -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&03 -F path=/etc/passwd -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b32 -S open -F a1&03 -F path=/etc/passwd -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&03 -F path=/etc/shadow -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&03 -F path=/etc/shadow -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b32 -S open -F a1&03 -F path=/etc/shadow -F auid>=1000 -F auid!=unset -F key=user-modify ## User enable and disable. This is entirely handled by pam. ## Group add delete modify. This is covered by pam. However, someone could ## open a file and directly create or modify a user, so we'll watch group and ## gshadow for writes -a always,exit -F arch=b32 -F path=/etc/passwd -F perm=wa -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b64 -F path=/etc/passwd -F perm=wa -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b32 -F path=/etc/shadow -F perm=wa -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b64 -F path=/etc/shadow -F perm=wa -F auid>=1000 -F auid!=unset -F key=user-modify -a always,exit -F arch=b32 -F path=/etc/group -F perm=wa -F auid>=1000 -F auid!=unset -F key=group-modify -a always,exit -F arch=b64 -F path=/etc/group -F perm=wa -F auid>=1000 -F auid!=unset -F key=group-modify -a always,exit -F arch=b32 -F path=/etc/gshadow -F perm=wa -F auid>=1000 -F auid!=unset -F key=group-modify -a always,exit -F arch=b64 -F path=/etc/gshadow -F perm=wa -F auid>=1000 -F auid!=unset -F key=group-modify ## Use of special rights for config changes. This would be use of setuid ## programs that relate to user accts. This is not all setuid apps because ## requirements are only for ones that affect system configuration. -a always,exit -F arch=b32 -F path=/usr/sbin/unix_chkpwd -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/sbin/unix_chkpwd -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/sbin/usernetctl -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/sbin/usernetctl -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/sbin/userhelper -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/sbin/userhelper -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/sbin/seunshare -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/sbin/seunshare -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/mount -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/mount -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/newgrp -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/newgrp -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/newuidmap -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/newuidmap -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/gpasswd -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/gpasswd -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/newgidmap -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/newgidmap -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/umount -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/umount -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/passwd -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/passwd -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/crontab -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/crontab -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/bin/at -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/bin/at -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b32 -F path=/usr/sbin/grub2-set-bootflag -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes -a always,exit -F arch=b64 -F path=/usr/sbin/grub2-set-bootflag -F perm=x -F auid>=1000 -F auid!=unset -F key=special-config-changes ## Privilege escalation via su or sudo. This is entirely handled by pam. ## Special case for systemd-run. It is not audit aware, specifically watch it -a always,exit -F arch=b32 -F path=/usr/bin/systemd-run -F perm=x -F auid!=unset -F key=maybe-escalation -a always,exit -F arch=b64 -F path=/usr/bin/systemd-run -F perm=x -F auid!=unset -F key=maybe-escalation ## Special case for pkexec. It is not audit aware, specifically watch it -a always,exit -F arch=b32 -F path=/usr/bin/pkexec -F perm=x -F key=maybe-escalation -a always,exit -F arch=b64 -F path=/usr/bin/pkexec -F perm=x -F key=maybe-escalation ## Watch for configuration changes to privilege escalation. -a always,exit -F arch=b32 -F path=/etc/sudoers -F perm=wa -F key=special-config-changes -a always,exit -F arch=b64 -F path=/etc/sudoers -F perm=wa -F key=special-config-changes -a always,exit -F arch=b32 -F dir=/etc/sudoers.d/ -F perm=wa -F key=special-config-changes -a always,exit -F arch=b64 -F dir=/etc/sudoers.d/ -F perm=wa -F key=special-config-changes ## Audit log access -a always,exit -F arch=b32 -F dir=/var/log/audit/ -F perm=r -F auid>=1000 -F auid!=unset -F key=access-audit-trail -a always,exit -F arch=b64 -F dir=/var/log/audit/ -F perm=r -F auid>=1000 -F auid!=unset -F key=access-audit-trail ## Attempts to Alter Process and Session Initiation Information -a always,exit -F arch=b32 -F path=/var/run/utmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session -a always,exit -F arch=b64 -F path=/var/run/utmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session -a always,exit -F arch=b32 -F path=/var/log/btmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session -a always,exit -F arch=b64 -F path=/var/log/btmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session -a always,exit -F arch=b32 -F path=/var/log/wtmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session -a always,exit -F arch=b64 -F path=/var/log/wtmp -F perm=wa -F auid>=1000 -F auid!=unset -F key=session ## Attempts to modify MAC controls -a always,exit -F arch=b32 -F dir=/etc/selinux/ -F perm=wa -F auid>=1000 -F auid!=unset -F key=MAC-policy -a always,exit -F arch=b64 -F dir=/etc/selinux/ -F perm=wa -F auid>=1000 -F auid!=unset -F key=MAC-policy ## Software updates. This is entirely handled by rpm. ## System start and shutdown. This is entirely handled by systemd ## Kernel Module loading. This is handled in 43-module-load.rules ## Application invocation. The requirements list an optional requirement ## FPT_SRP_EXT.1 Software Restriction Policies. This event is intended to ## state results from that policy. This would be handled entirely by ## that daemon.Load new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing of events listed in the description provides data for monitoring and investigation of potentially malicious events e.g. tampering with Audit logs, malicious access to files storing information about system users and groups etc. |
| IA-2 AC-6(5) IA-4(b) |
Verify Only Root Has UID 0 |
If any account other than root has a UID of 0, this misconfiguration should
be investigated and the accounts other than root should be removed or have
their UID changed.
If the account is associated with system commands or applications the UID should be changed to one greater than "0" but less than "1000." Otherwise assign a UID greater than "1000" that has not already been assigned. |
An account has root authority if it has a UID of 0. Multiple accounts with a UID of 0 afford more opportunity for potential intruders to guess a password for a privileged account. Proper configuration of sudo is recommended to afford multiple system administrators access to root privileges in an accountable manner. |
| AU-2(a) | Configure auditing of successful file creations (ppc64le) |
Ensure that successful attempts to create a file are audited.
The following rules configure audit as described above:
## Successful file creation (open with O_CREAT) -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&0100 -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-create -a always,exit -F arch=b64 -S open -F a1&0100 -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-create -a always,exit -F arch=b64 -S creat -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-createLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing of successful attempts to create a file helps in investigation of actions which happened on the system. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record attempts to alter time through adjtimex |
If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following line to a file with suffix .rules in the
directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S adjtimex -F key=audit_time_rulesIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S adjtimex -F key=audit_time_rulesIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S adjtimex -F key=audit_time_rulesIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S adjtimex -F key=audit_time_rulesThe -k option allows for the specification of a key in string form that can be used for better reporting capability through ausearch and aureport. Multiple system calls can be defined on the same line to save space if desired, but is not required. See an example of multiple combined syscalls: -a always,exit -F arch=b64 -S adjtimex,settimeofday -F key=audit_time_rules |
Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited. |
| AU-2(a) | Configure auditing of successful ownership changes (AArch64) |
Ensure that successful attempts to change an ownership of files or directories are audited.
The following rules configure audit as described above:
## Successful ownership change -a always,exit -F arch=b32 -S lchown,fchown,chown,fchownat -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-owner-change -a always,exit -F arch=b64 -S fchown,fchownat -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-owner-changeLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing of successful ownership changes of files or directories helps in monitoring or investingating of activities performed on the system. |
| AU-2(a) | Configure auditing of successful file accesses |
Ensure that successful attempts to access a file are audited.
The following rules configure audit as described above:
## Successful file access (any other opens) This has to go last. ## These next two are likely to result in a whole lot of events -a always,exit -F arch=b32 -S open,openat,openat2,open_by_handle_at -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-access -a always,exit -F arch=b64 -S open,openat,openat2,open_by_handle_at -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-accessLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing of successful attempts to access a file helps in investigation of activities performed on the system. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on Kernel Module Loading - init_module |
To capture kernel module loading events, use following line, setting ARCH to
either b32 for 32-bit system, or having two lines for both b32 and b64 in case your system is 64-bit:
-a always,exit -F arch=ARCH -S init_module -F auid>=1000 -F auid!=unset -F key=modulesPlace to add the line depends on a way auditd daemon is configured. If it is configured to use the augenrules program (the default), add the line to a file with suffix .rules in the directory /etc/audit/rules.d. If the auditd daemon is configured to use the auditctl utility, add the line to file /etc/audit/audit.rules. |
The addition of kernel modules can be used to alter the behavior of the kernel and potentially introduce malicious code into kernel space. It is important to have an audit trail of modules that have been introduced into the kernel. |
| AU-2(d) AU-12(c) CM-6(a) |
Ensure auditd Rules For Unauthorized Attempts To openat Are Ordered Correctly |
The audit system should collect detailed unauthorized file
accesses for all users and root.
To correctly identify unsuccessful creation, unsuccessful modification and unsuccessful access
of files via openat syscall the audit rules collecting these events need to be in certain order.
The more specific rules need to come before the less specific rules. The reason for that is that more
specific rules cover a subset of events covered in the less specific rules, thus, they need to come
before to not be overshadowed by less specific rules, which match a bigger set of events.
Make sure that rules for unsuccessful calls of openat syscall are in the order shown below.
If the auditd daemon is configured to use the augenrules
program to read audit rules during daemon startup (the default), check the order of
rules below in a file with suffix .rules in the directory
/etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, check the order of rules below in
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S openat -F a2&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b32 -S openat -F a2&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b32 -S openat -F a2&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b32 -S openat -F a2&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b32 -S openat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-access -a always,exit -F arch=b32 -S openat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-accessIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S openat -F a2&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b64 -S openat -F a2&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b64 -S openat -F a2&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b64 -S openat -F a2&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b64 -S openat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-access -a always,exit -F arch=b64 -S openat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-access |
The more specific rules cover a subset of events covered by the less specific rules. By ordering them from more specific to less specific, it is assured that the less specific rule will not catch events better recorded by the more specific rule. |
| AU-2(d) AU-12(c) CM-6(a) |
Ensure auditd Collects File Deletion Events by User |
At a minimum the audit system should collect file deletion events
for all users and root. If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following line to a file with suffix .rules in the
directory /etc/audit/rules.d, setting ARCH to either b32 or b64 as
appropriate for your system:
-a always,exit -F arch=ARCH -S rmdir,unlink,unlinkat,rename,renameat -F auid>=1000 -F auid!=unset -F key=deleteIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file, setting ARCH to either b32 or b64 as appropriate for your system: -a always,exit -F arch=ARCH -S rmdir,unlink,unlinkat,rename -S renameat -F auid>=1000 -F auid!=unset -F key=delete |
Auditing file deletions will create an audit trail for files that are removed from the system. The audit trail could aid in system troubleshooting, as well as, detecting malicious processes that attempt to delete log files to conceal their presence. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Events that Modify the System's Discretionary Access Controls - lsetxattr |
At a minimum, the audit system should collect file permission
changes for all users and root. If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following line to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S lsetxattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b32 -S lsetxattr -F auid=0 -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S lsetxattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b64 -S lsetxattr -F auid=0 -F key=perm_modIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S lsetxattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b32 -S lsetxattr -F auid=0 -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S lsetxattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b64 -S lsetxattr -F auid=0 -F key=perm_mod |
The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Any Attempts to Run setfiles |
At a minimum, the audit system should collect any execution attempt
of the setfiles command for all users and root. If the auditd
daemon is configured to use the augenrules program to read audit rules
during daemon startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/sbin/setfiles -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F path=/usr/sbin/setfiles -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Attempts to Alter Time Through stime |
If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following line to a file with suffix .rules in the
directory /etc/audit/rules.d for both 32 bit and 64 bit systems:
-a always,exit -F arch=b32 -S stime -F key=audit_time_rulesSince the 64 bit version of the "stime" system call is not defined in the audit lookup table, the corresponding "-F arch=b64" form of this rule is not expected to be defined on 64 bit systems (the aforementioned "-F arch=b32" stime rule form itself is sufficient for both 32 bit and 64 bit systems). If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file for both 32 bit and 64 bit systems: -a always,exit -F arch=b32 -S stime -F key=audit_time_rulesSince the 64 bit version of the "stime" system call is not defined in the audit lookup table, the corresponding "-F arch=b64" form of this rule is not expected to be defined on 64 bit systems (the aforementioned "-F arch=b32" stime rule form itself is sufficient for both 32 bit and 64 bit systems). The -k option allows for the specification of a key in string form that can be used for better reporting capability through ausearch and aureport. Multiple system calls can be defined on the same line to save space if desired, but is not required. See an example of multiple combined system calls: -a always,exit -F arch=b64 -S adjtimex,settimeofday -F key=audit_time_rules |
Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - sudoedit |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/bin/sudoedit -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/bin/sudoedit -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Modification Attempts to Files - openat O_TRUNC_WRITE |
The audit system should collect detailed unauthorized file accesses for
all users and root. The openat syscall can be used to modify files
if called for write operation of with O_TRUNC_WRITE flag.
The following auidt rules will asure that unsuccessful attempts to modify a
file via openat syscall are collected.
If the auditd daemon is configured to use the augenrules
program to read audit rules during daemon startup (the default), add the
rules below to a file with suffix .rules in the directory
/etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the rules below to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S openat -F a2&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b32 -S openat -F a2&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modificationIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S openat -F a2&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b64 -S openat -F a2&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification |
Unsuccessful attempts to access files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(a) | Configure auditing of unsuccessful file deletions (AArch64) |
Ensure that unsuccessful attempts to delete a file are audited.
The following rules configure audit as described above:
## Unsuccessful file delete -a always,exit -F arch=b32 -S unlink,unlinkat,rename,renameat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete -a always,exit -F arch=b64 -S unlinkat,renameat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete -a always,exit -F arch=b32 -S unlink,unlinkat,rename,renameat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete -a always,exit -F arch=b64 -S unlinkat,renameat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-deleteLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Unsuccessful attempts to delete a file might be signs of malicious activities. Auditing of such events help in monitoring and investigating of such activities. |
| AC-2(g) AU-3 AU-10 AU-2(d) AU-12(c) AU-14(1) AC-6(9) CM-6(a) SI-4(23) |
Enable auditd Service |
The auditd service is an essential userspace component of
the Linux Auditing System, as it is responsible for writing audit records to
disk.
The auditd service can be enabled with the following command:
$ sudo systemctl enable auditd.service |
Without establishing what type of events occurred, it would be difficult
to establish, correlate, and investigate the events leading up to an outage or attack.
Ensuring the auditd service is active ensures audit records
generated by the kernel are appropriately recorded.
Additionally, a properly configured audit subsystem ensures that actions of individual system users can be uniquely traced to those users so they can be held accountable for their actions. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Events that Modify the System's Discretionary Access Controls - fsetxattr |
At a minimum, the audit system should collect file permission
changes for all users and root. If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following line to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S fsetxattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b32 -S fsetxattr -F auid=0 -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S fsetxattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b64 -S fsetxattr -F auid=0 -F key=perm_modIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S fsetxattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b32 -S fsetxattr -F auid=0 -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S fsetxattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b64 -S fsetxattr -F auid=0 -F key=perm_mod |
The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Delete Attempts to Files - rename |
The audit system should collect unsuccessful file deletion
attempts for all users and root. If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the following lines to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S rename -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete -a always,exit -F arch=b32 -S rename -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-deleteIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S rename -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete -a always,exit -F arch=b64 -S rename -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete |
Unsuccessful attempts to delete files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(a) | Configure auditing of successful permission changes (AArch64) |
Ensure that successful attempts to modify permissions of files or directories are audited.
The following rules configure audit as described above:
## Successful permission change -a always,exit -F arch=b32 -S chmod,fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-perm-change -a always,exit -F arch=b64 -S fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-perm-changeLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing successful file or directory permission changes helps in monitoring and investigating of activities performed on the system. |
| AU-2(a) | Configure auditing of unsuccessful file creations (ppc64le) |
Ensure that unsuccessful attempts to create a file are audited.
The following rules configure audit as described above:
## Unsuccessful file creation (open with O_CREAT) -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b64 -S open -F a1&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b64 -S creat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b64 -S open -F a1&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-create -a always,exit -F arch=b64 -S creat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-createLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Unsuccessful file creations might be a sign of a malicious action being performed on the system. Keeping log of such events helps in monitoring and investigation of such actions. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - at |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/bin/at -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/bin/at -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| IA-2 CM-6(a) |
All GIDs referenced in /etc/passwd must be defined in /etc/group | Add a group to the system for each GID referenced without a corresponding group. | If a user is assigned the Group Identifier (GID) of a group not existing on the system, and a group with the Group Identifier (GID) is subsequently created, the user may have unintended rights to any files associated with the group. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Access Attempts to Files - open_by_handle_at |
At a minimum, the audit system should collect unauthorized file
accesses for all users and root. If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S open_by_handle_at -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b32 -S open_by_handle_at -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S open_by_handle_at -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b64 -S open_by_handle_at -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S open_by_handle_at,truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b32 -S open_by_handle_at,truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S open_by_handle_at,truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b64 -S open_by_handle_at,truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=access |
Unsuccessful attempts to access files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) CM-6(a) |
Ensure auditd Collects File Deletion Events by User - rename |
At a minimum, the audit system should collect file deletion events
for all users and root. If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following line to a file with suffix .rules in the
directory /etc/audit/rules.d, setting ARCH to either b32 or b64 as
appropriate for your system:
-a always,exit -F arch=ARCH -S rename -F auid>=1000 -F auid!=unset -F key=deleteIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file, setting ARCH to either b32 or b64 as appropriate for your system: -a always,exit -F arch=ARCH -S rename -F auid>=1000 -F auid!=unset -F key=delete |
Auditing file deletions will create an audit trail for files that are removed from the system. The audit trail could aid in system troubleshooting, as well as, detecting malicious processes that attempt to delete log files to conceal their presence. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record attempts to alter time through settimeofday |
If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following line to a file with suffix .rules in the
directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S settimeofday -F key=audit_time_rulesIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S settimeofday -F key=audit_time_rulesIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S settimeofday -F key=audit_time_rulesIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S settimeofday -F key=audit_time_rulesThe -k option allows for the specification of a key in string form that can be used for better reporting capability through ausearch and aureport. Multiple system calls can be defined on the same line to save space if desired, but is not required. See an example of multiple combined syscalls: -a always,exit -F arch=b64 -S adjtimex,settimeofday -F key=audit_time_rules |
Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Events that Modify the System's Discretionary Access Controls - removexattr |
At a minimum, the audit system should collect file permission
changes for all users and root.
If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following line to a file with suffix .rules in the directory /etc/audit/rules.d: -a always,exit -F arch=b32 -S removexattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b32 -S removexattr -F auid=0 -F key=perm_mod If the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S removexattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b64 -S removexattr -F auid=0 -F key=perm_mod If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S removexattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b32 -S removexattr -F auid=0 -F key=perm_mod If the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S removexattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b64 -S removexattr -F auid=0 -F key=perm_mod |
The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Events that Modify the System's Discretionary Access Controls - fchmod |
At a minimum, the audit system should collect file permission
changes for all users and root. If the auditd daemon is configured to
use the augenrules program to read audit rules during daemon startup
(the default), add the following line to a file with suffix .rules in
the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S fchmod -F auid>=1000 -F auid!=unset -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S fchmod -F auid>=1000 -F auid!=unset -F key=perm_modIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S fchmod -F auid>=1000 -F auid!=unset -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S fchmod -F auid>=1000 -F auid!=unset -F key=perm_mod |
The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Delete Attempts to Files - renameat |
The audit system should collect unsuccessful file deletion
attempts for all users and root. If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the following lines to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S renameat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete -a always,exit -F arch=b32 -S renameat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-deleteIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S renameat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete -a always,exit -F arch=b64 -S renameat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete |
Unsuccessful attempts to delete files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - ssh-keysign |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/libexec/openssh/ssh-keysign -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/libexec/openssh/ssh-keysign -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on Exporting to Media (successful) |
At a minimum, the audit system should collect media exportation
events for all users and root. If the auditd daemon is configured to
use the augenrules program to read audit rules during daemon startup
(the default), add the following line to a file with suffix .rules in
the directory /etc/audit/rules.d, setting ARCH to either b32 or b64 as
appropriate for your system:
-a always,exit -F arch=ARCH -S mount -F auid>=1000 -F auid!=unset -F key=exportIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file, setting ARCH to either b32 or b64 as appropriate for your system: -a always,exit -F arch=ARCH -S mount -F auid>=1000 -F auid!=unset -F key=export |
The unauthorized exportation of data to external media could result in an information leak where classified information, Privacy Act information, and intellectual property could be lost. An audit trail should be created each time a filesystem is mounted to help identify and guard against information loss. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - userhelper |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/sbin/userhelper -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/sbin/userhelper -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Ownership Changes to Files - fchownat |
The audit system should collect unsuccessful file ownership change
attempts for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the following lines to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S fchownat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b32 -S fchownat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-changeIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S fchownat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b64 -S fchownat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change |
Unsuccessful attempts to change ownership of files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - pam_timestamp_check |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/sbin/pam_timestamp_check -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/sbin/pam_timestamp_check -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Ownership Changes to Files - fchown |
The audit system should collect unsuccessful file ownership change
attempts for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the following lines to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S fchown -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b32 -S fchown -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-changeIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S fchown -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b64 -S fchown -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change |
Unsuccessful attempts to change ownership of files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Events that Modify the System's Discretionary Access Controls - lchown |
At a minimum, the audit system should collect file permission
changes for all users and root. If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following line to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S lchown -F auid>=1000 -F auid!=unset -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S lchown -F auid>=1000 -F auid!=unset -F key=perm_modIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S lchown -F auid>=1000 -F auid!=unset -F key=perm_modIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S lchown -F auid>=1000 -F auid!=unset -F key=perm_mod |
The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Delete Attempts to Files - unlinkat |
The audit system should collect unsuccessful file deletion
attempts for all users and root. If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the following lines to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S unlinkat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete -a always,exit -F arch=b32 -S unlinkat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-deleteIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S unlinkat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete -a always,exit -F arch=b64 -S unlinkat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-delete |
Unsuccessful attempts to delete files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Attempts to Alter Time Through clock_settime |
If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following line to a file with suffix .rules in the
directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S clock_settime -F a0=0x0 -F key=time-changeIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S clock_settime -F a0=0x0 -F key=time-changeIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S clock_settime -F a0=0x0 -F key=time-changeIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S clock_settime -F a0=0x0 -F key=time-changeThe -k option allows for the specification of a key in string form that can be used for better reporting capability through ausearch and aureport. Multiple system calls can be defined on the same line to save space if desired, but is not required. See an example of multiple combined syscalls: -a always,exit -F arch=b64 -S adjtimex,settimeofday -F key=audit_time_rules |
Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited. |
| AU-2(a) | Configure auditing of unsuccessful file modifications (ppc64le) |
Ensure that unsuccessful attempts to modify a file are audited.
The following rules configure audit as described above:
## Unsuccessful file modifications (open for write or truncate) -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b64 -S open -F a1&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b64 -S truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b64 -S open -F a1&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-modification -a always,exit -F arch=b64 -S truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-modificationLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Unsuccessful file modifications might be a sign of a malicious action being performed on the system. Auditing of such events helps in detection and investigation of such actions. |
| AU-2 CM-8(3) IA-3 |
Log USBGuard daemon audit events using Linux Audit | To configure USBGuard daemon to log via Linux Audit (as opposed directly to a file), AuditBackend option in /etc/usbguard/usbguard-daemon.conf needs to be set to LinuxAudit. | Using the Linux Audit logging allows for centralized trace of events. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - pt_chown |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/libexec/pt_chown -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/libexec/pt_chown -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Any Attempts to Run chcon |
At a minimum, the audit system should collect any execution attempt
of the chcon command for all users and root. If the auditd
daemon is configured to use the augenrules program to read audit rules
during daemon startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/bin/chcon -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F path=/usr/bin/chcon -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AU-2(a) | Configure auditing of unsuccessful file accesses |
Ensure that unsuccessful attempts to access a file are audited.
The following rules configure audit as described above:
## Unsuccessful file access (any other opens) This has to go last. -a always,exit -F arch=b32 -S open,openat,openat2,open_by_handle_at -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-access -a always,exit -F arch=b64 -S open,openat,openat2,open_by_handle_at -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-access -a always,exit -F arch=b32 -S open,openat,openat2,open_by_handle_at -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-access -a always,exit -F arch=b64 -S open,openat,openat2,open_by_handle_at -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-accessLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Unsuccessful attempts to access a file might be signs of malicious activity happening within the system. Auditing of such activities helps in their monitoring and investigation. |
| AU-2(a) | Configure auditing of successful file modifications (AArch64) |
Ensure that successful attempts to modify a file are audited.
The following rules configure audit as described above:
## Successful file modifications (open for write or truncate) -a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&01003 -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-modification -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&01003 -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-modification -a always,exit -F arch=b32 -S open -F a1&01003 -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-modification -a always,exit -F arch=b32 -S truncate,ftruncate -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-modification -a always,exit -F arch=b64 -S truncate,ftruncate -F success=1 -F auid>=1000 -F auid!=unset -F key=successful-modificationLoad new Audit rules into kernel by running: augenrules --loadNote: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs. |
Auditing of successful attempts to modify a file helps in investigation of actions which happened on the system. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Permission Changes to Files - fchmodat |
The audit system should collect unsuccessful file permission change
attempts for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the following lines to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S fchmodat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b32 -S fchmodat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-changeIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S fchmodat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b64 -S fchmodat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change |
Unsuccessful attempts to change permissions of files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - su |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/bin/su -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/bin/su -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Permission Changes to Files - lsetxattr |
The audit system should collect unsuccessful file permission change
attempts for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the following lines to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S lsetxattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b32 -S lsetxattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-changeIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S lsetxattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b64 -S lsetxattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change |
Unsuccessful attempts to change permissions of files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Access Events to Audit Log Directory |
The audit system should collect access events to read audit log directory.
The following audit rule will assure that access to audit log directory are
collected.
-a always,exit -F dir=/var/log/audit/ -F perm=r -F auid>=1000 -F auid!=unset -F key=access-audit-trailIf the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the rule to a file with suffix .rules in the directory /etc/audit/rules.d. If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the rule to /etc/audit/audit.rules file. |
Attempts to read the logs should be recorded, suspicious access to audit log files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise.' |
| AU-2(a) | Configure auditing of loading and unloading of kernel modules (ppc64le) |
Ensure that loading and unloading of kernel modules is audited.
The following rules configure audit as described above:
## These rules watch for kernel module insertion. By monitoring ## the syscall, we do not need any watches on programs. -a always,exit -F arch=b64 -S init_module,finit_module -F key=module-load -a always,exit -F arch=b64 -S delete_module -F key=module-unloadLoad new Audit rules into kernel by running: augenrules --load |
Loading of a malicious kernel module introduces a risk to the system, as the module has access to sensitive data and perform actions at the operating system kernel level. Having such events audited helps in monitoring and investigating of malicious activities. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Permission Changes to Files - lremovexattr |
The audit system should collect unsuccessful file permission change
attempts for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the following lines to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S lremovexattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b32 -S lremovexattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-changeIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S lremovexattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b64 -S lremovexattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change |
Unsuccessful attempts to change permissions of files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Permission Changes to Files - removexattr |
The audit system should collect unsuccessful file permission change
attempts for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, add the following lines to
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S removexattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b32 -S removexattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-changeIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S removexattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change -a always,exit -F arch=b64 -S removexattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-perm-change |
Unsuccessful attempts to change permissions of files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - crontab |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/bin/crontab -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/bin/crontab -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Access Attempts to Files - ftruncate |
At a minimum, the audit system should collect unauthorized file
accesses for all users and root. If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b32 -S ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b64 -S ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b32 -S ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b64 -S ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=access |
Unsuccessful attempts to access files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Unsuccessful Access Attempts to Files - truncate |
At a minimum, the audit system should collect unauthorized file
accesses for all users and root. If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S truncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b32 -S truncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S truncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b64 -S truncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S truncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b32 -S truncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=accessIf the system is 64 bit then also add the following lines: -a always,exit -F arch=b64 -S truncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access -a always,exit -F arch=b64 -S truncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=access |
Unsuccessful attempts to access files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AU-2(d) AU-12(c) CM-6(a) |
Record Events that Modify the System's Discretionary Access Controls - fremovexattr |
At a minimum, the audit system should collect file permission
changes for all users and root.
If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following line to a file with suffix .rules in the directory /etc/audit/rules.d: -a always,exit -F arch=b32 -S fremovexattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b32 -S fremovexattr -F auid=0 -F key=perm_mod If the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S fremovexattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b64 -S fremovexattr -F auid=0 -F key=perm_mod If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S fremovexattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b32 -S fremovexattr -F auid=0 -F key=perm_mod If the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S fremovexattr -F auid>=1000 -F auid!=unset -F key=perm_mod -a always,exit -F arch=b64 -S fremovexattr -F auid=0 -F key=perm_mod |
The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users. |
| AU-2(d) AU-12(c) CM-6(a) |
Ensure auditd Collects File Deletion Events by User - rmdir |
At a minimum, the audit system should collect file deletion events
for all users and root. If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following line to a file with suffix .rules in the
directory /etc/audit/rules.d, setting ARCH to either b32 or b64 as
appropriate for your system:
-a always,exit -F arch=ARCH -S rmdir -F auid>=1000 -F auid!=unset -F key=deleteIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file, setting ARCH to either b32 or b64 as appropriate for your system: -a always,exit -F arch=ARCH -S rmdir -F auid>=1000 -F auid!=unset -F key=delete |
Auditing file deletions will create an audit trail for files that are removed from the system. The audit trail could aid in system troubleshooting, as well as, detecting malicious processes that attempt to delete log files to conceal their presence. |
| IA-2(1) IA-2(2) IA-2(3) IA-2(4) IA-2(6) IA-2(7) IA-2(11) CM-6(a) |
Enable Smart Card Login |
To enable smart card authentication, consult the documentation at:
|
Smart card login provides two-factor authentication stronger than that provided by a username and password combination. Smart cards leverage PKI (public key infrastructure) in order to provide and verify credentials. |
| IA-2(1) IA-2(2) IA-2(3) IA-2(4) IA-2(6) IA-2(7) IA-2(11) CM-6(a) |
Configure NSS DB To Use opensc |
The opensc module should be configured for use over the
Coolkey PKCS#11 module in the NSS database. To configure the
NSS database to use the opensc module, run the following
command:
$ sudo pkcs11-switch opensc |
Smart card login provides two-factor authentication stronger than that provided by a username and password combination. Smart cards leverage PKI (public key infrastructure) in order to provide and verify credentials. |
| SC-2(1) CM-6(a) |
Verify that Interactive Boot is Disabled | Red Hat Enterprise Linux 8 systems support an "interactive boot" option that can be used to prevent services from being started. On a Red Hat Enterprise Linux 8 system, interactive boot can be enabled by providing a 1, yes, true, or on value to the systemd.confirm_spawn kernel argument. | Using interactive boot, the console user could disable auditing, firewalls, or other services, weakening system security. |
| IA-2(1) CM-6(a) |
Configure PAM in SSSD Services |
SSSD should be configured to run SSSD pam services.
To configure SSSD to known SSH hosts, add pam
to services under the [sssd] section in
/etc/sssd/sssd.conf. For example:
[sssd] services = sudo, autofs, pam |
Using an authentication device, such as a CAC or token that is separate from the information system, ensures that even if the information system is compromised, that compromise will not affect credentials stored on the authentication device. |
| SC-2(1) CM-6(a) |
Verify that Interactive Boot is Disabled |
Red Hat Enterprise Linux 8 systems support an "interactive boot" option that can
be used to prevent services from being started. On a Red Hat Enterprise Linux 8
system, interactive boot can be enabled by providing a 1,
yes, true, or on value to the
systemd.confirm_spawn kernel argument in /etc/default/grub.
Remove any instance of systemd.confirm_spawn=(1|yes|true|on)from the kernel arguments in that file to disable interactive boot. Recovery booting must also be disabled. Confirm that GRUB_DISABLE_RECOVERY=true is set in /etc/default/grub. It is also required to change the runtime configuration, run: /sbin/grubby --update-kernel=ALL --remove-args="systemd.confirm_spawn" grub2-mkconfig -o /boot/grub2/grub.cfg |
Using interactive or recovery boot, the console user could disable auditing, firewalls, or other services, weakening system security. |
| AC-2(1) | Ensure PAM Enforces Password Requirements - Enforce for Local Accounts Only | The pam_pwquality module's local_users_only parameter controls requirements for enforcing password complexity by pam_pwquality only for local user accounts and ignoring centralized user account management password complexity configurations. Enable the local_users_only setting in /etc/security/pwquality.conf to require password complexity enforcement for only local user accounts. | The operating system must provide automated mechanisms for supporting account management functions. Enterprise environments make application account management challenging and complex. A manual process for account management functions adds the risk of a potential oversight or other error. |
| IA-2(1) IA-2(2) IA-2(3) IA-2(4) IA-2(6) IA-2(7) IA-2(11) CM-6(a) |
Configure opensc Smart Card Drivers |
The OpenSC smart card tool can auto-detect smart card drivers; however,
setting the smart card drivers in use by your organization helps to prevent
users from using unauthorized smart cards. The default smart card driver for this
profile is default.
To configure the OpenSC driver, edit the /etc/opensc.conf
and add the following line into the file in the app default block,
so it will look like:
app default {
...
card_drivers = default;
}
|
Smart card login provides two-factor authentication stronger than that provided by a username and password combination. Smart cards leverage PKI (public key infrastructure) in order to provide and verify credentials. Configuring the smart card driver in use by your organization helps to prevent users from using unauthorized smart cards. |
| IA-2(1) IA-2(2) IA-2(3) IA-2(4) IA-2(6) IA-2(7) IA-2(11) CM-6(a) |
Enable the pcscd Service |
The pcscd service can be enabled with the following command:
$ sudo systemctl enable pcscd.service |
Using an authentication device, such as a CAC or token that is separate from
the information system, ensures that even if the information system is
compromised, that compromise will not affect credentials stored on the
authentication device.
Multifactor solutions that require devices separate from information systems gaining access include, for example, hardware tokens providing time-based or challenge-response authenticators and smart cards such as the U.S. Government Personal Identity Verification card and the DoD Common Access Card. |
| AC-2(1) | Enforce pam_faillock for Local Accounts Only | The pam_faillock module's local_users_only parameter controls requirements for enforcing failed lockout attempts only for local user accounts and ignoring centralized user account management failed attempt configurations. | The operating system must provide automated mechanisms for supporting account management functions. Enterprise environments make application account management challenging and complex. A manual process for account management functions adds the risk of a potential oversight or other error. Locking out remote accounts may cause unintentional DoS. |
| IA-2(1) IA-2(2) IA-2(3) IA-2(4) IA-2(6) IA-2(7) IA-2(11) CM-6(a) |
Force opensc To Use Defined Smart Card Driver |
The OpenSC smart card middleware can auto-detect smart card drivers; however by
forcing the smart card driver in use by your organization, opensc will no longer
autodetect or use other drivers unless specified. This helps to prevent
users from using unauthorized smart cards. The default smart card driver for this
profile is default.
To force the OpenSC driver, edit the /etc/opensc.conf.
Look for a line similar to:
# force_card_driver = customcos;and change it to: force_card_driver = default; |
Smart card login provides two-factor authentication stronger than that provided by a username and password combination. Smart cards leverage PKI (public key infrastructure) in order to provide and verify credentials. Forcing the smart card driver in use by your organization helps to prevent users from using unauthorized smart cards. |
| SI-2(2) | Ensure McAfee Endpoint Security for Linux (ENSL) is running | Install McAfee Endpoint Security for Linux antivirus software which is provided for DoD systems and uses signatures to search for the presence of viruses on the filesystem. | Virus scanning software can be used to detect if a system has been compromised by computer viruses, as well as to limit their spread to other systems. |
| AC-2(2) AC-2(3) CM-6(a) |
Assign Expiration Date to Temporary Accounts |
Temporary accounts are established as part of normal account activation
procedures when there is a need for short-term accounts. In the event
temporary accounts are required, configure the system to
terminate them after a documented time period. For every temporary account, run the following command to set an expiration date on
it, substituting USER and YYYY-MM-DD
appropriately:
$ sudo chage -E YYYY-MM-DD USERYYYY-MM-DD indicates the documented expiration date for the account. For U.S. Government systems, the operating system must be configured to automatically terminate these types of accounts after a period of 72 hours. |
If temporary user accounts remain active when no longer needed or for
an excessive period, these accounts may be used to gain unauthorized access.
To mitigate this risk, automated termination of all temporary accounts
must be set upon account creation.
|
| AC-2(2) AC-2(3) CM-6(a) |
Assign Expiration Date to Emergency Accounts |
Emergency accounts are privileged accounts established in response to
crisis situations where the need for rapid account activation is required.
In the event emergency accounts are required, configure the system to
terminate them after a documented time period. For every emergency account,
run the following command to set an expiration date on it, substituting
ACCOUNT_NAME and YYYY-MM-DD
appropriately:
$ sudo chage -E YYYY-MM-DD ACCOUNT_NAMEYYYY-MM-DD indicates the documented expiration date for the account. For U.S. Government systems, the operating system must be configured to automatically terminate these types of accounts after a period of 72 hours. |
If emergency user accounts remain active when no longer needed or for
an excessive period, these accounts may be used to gain unauthorized access.
To mitigate this risk, automated termination of all emergency accounts
must be set upon account creation.
|
| SI-2(2) | Install McAfee Endpoint Security for Linux (ENSL) |
Install McAfee Endpoint Security for Linux antivirus software
which is provided for DoD systems and uses signatures to search for the
presence of viruses on the filesystem.
The McAfeeTP package can be installed with the following command:
$ sudo yum install McAfeeTP |
Virus scanning software can be used to detect if a system has been compromised by computer viruses, as well as to limit their spread to other systems. |
| IA-2(3) IA-2(4) IA-2(8) IA-2(9) IA-2(11) |
Enable the GNOME3 Login Smartcard Authentication |
In the default graphical environment, smart card authentication
can be enabled on the login screen by setting enable-smartcard-authentication
to true.
To enable, add or edit enable-smartcard-authentication to /etc/dconf/db/gdm.d/00-security-settings. For example: [org/gnome/login-screen] enable-smartcard-authentication=trueOnce the setting has been added, add a lock to /etc/dconf/db/gdm.d/locks/00-security-settings-lock to prevent user modification. For example: /org/gnome/login-screen/enable-smartcard-authenticationAfter the settings have been set, run dconf update. |
Smart card login provides two-factor authentication stronger than that provided by a username and password combination. Smart cards leverage PKI (public key infrastructure) in order to provide and verify credentials. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify User/Group Information - /etc/security/opasswd |
If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following lines to a file with suffix .rules in the
directory /etc/audit/rules.d, in order to capture events that modify
account changes:
-w /etc/security/opasswd -p wa -k audit_rules_usergroup_modification If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file, in order to capture events that modify account changes: -w /etc/security/opasswd -p wa -k audit_rules_usergroup_modification |
In addition to auditing new user and group accounts, these watches will alert the system administrator(s) to any modifications. Any unexpected users, groups, or modifications should be investigated for legitimacy. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify User/Group Information |
If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following lines to a file with suffix .rules in the
directory /etc/audit/rules.d, in order to capture events that modify
account changes:
-w /etc/group -p wa -k audit_rules_usergroup_modification -w /etc/passwd -p wa -k audit_rules_usergroup_modification -w /etc/gshadow -p wa -k audit_rules_usergroup_modification -w /etc/shadow -p wa -k audit_rules_usergroup_modification -w /etc/security/opasswd -p wa -k audit_rules_usergroup_modification If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file, in order to capture events that modify account changes: -w /etc/group -p wa -k audit_rules_usergroup_modification -w /etc/passwd -p wa -k audit_rules_usergroup_modification -w /etc/gshadow -p wa -k audit_rules_usergroup_modification -w /etc/shadow -p wa -k audit_rules_usergroup_modification -w /etc/security/opasswd -p wa -k audit_rules_usergroup_modification |
In addition to auditing new user and group accounts, these watches will alert the system administrator(s) to any modifications. Any unexpected users, groups, or modifications should be investigated for legitimacy. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - chage |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/bin/chage -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/bin/chage -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands |
The audit system should collect information about usage of privileged commands for all users.
These are commands with suid or sgid bits on and they are specially risky in local block
device partitions not mounted with noexec and nosuid options. Therefore, these partitions
should be first identified by the following command:
findmnt -n -l -k -it $(awk '/nodev/ { print $2 }' /proc/filesystems | paste -sd,) | grep -Pv "noexec|nosuid"
For all partitions listed by the previous command, it is necessary to search for
setuid / setgid programs using the following command:
$ sudo find PARTITION -xdev -perm /6000 -type f 2>/dev/nullFor each setuid / setgid program identified by the previous command, an audit rule must be present in the appropriate place using the following line structure: -a always,exit -F path=PROG_PATH -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup, add the line to a file with suffix .rules in the /etc/audit/rules.d directory, replacing the PROG_PATH part with the full path of that setuid / setgid identified program. If the auditd daemon is configured to use the auditctl utility instead, add the line to the /etc/audit/audit.rules file, also replacing the PROG_PATH part with the full path of that setuid / setgid identified program. |
Misuse of privileged functions, either intentionally or unintentionally by authorized users,
or by unauthorized external entities that have compromised system accounts, is a serious and
ongoing concern that can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify the
risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - gpasswd |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/bin/gpasswd -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/bin/gpasswd -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify User/Group Information via open_by_handle_at syscall - /etc/passwd |
The audit system should collect write events to /etc/passwd file for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S open_by_handle_at -F a2&03 -F path=/etc/passwd -F auid>=1000 -F auid!=unset -F key=modifyIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S open_by_handle_at -F a2&03 -F path=/etc/passwd -F auid>=1000 -F auid!=unset -F key=modifyIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S open_by_handle_at -F a2&03 -F path=/etc/passwd -F auid>=1000 -F auid!=unset -F key=modify |
Creation of users through direct edition of /etc/passwd could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify User/Group Information - /etc/shadow |
If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following lines to a file with suffix .rules in the
directory /etc/audit/rules.d, in order to capture events that modify
account changes:
-w /etc/shadow -p wa -k audit_rules_usergroup_modification If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file, in order to capture events that modify account changes: -w /etc/shadow -p wa -k audit_rules_usergroup_modification |
In addition to auditing new user and group accounts, these watches will alert the system administrator(s) to any modifications. Any unexpected users, groups, or modifications should be investigated for legitimacy. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify User/Group Information via open_by_handle_at syscall - /etc/group |
The audit system should collect write events to /etc/group file for all group and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S open_by_handle_at -F a2&03 -F path=/etc/group -F auid>=1000 -F auid!=unset -F key=modifyIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S open_by_handle_at -F a2&03 -F path=/etc/group -F auid>=1000 -F auid!=unset -F key=modifyIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S open_by_handle_at -F a2&03 -F path=/etc/group -F auid>=1000 -F auid!=unset -F key=modify |
Creation of groups through direct edition of /etc/group could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify User/Group Information - /etc/group |
If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following lines to a file with suffix .rules in the
directory /etc/audit/rules.d, in order to capture events that modify
account changes:
-w /etc/group -p wa -k audit_rules_usergroup_modification If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file, in order to capture events that modify account changes: -w /etc/group -p wa -k audit_rules_usergroup_modification |
In addition to auditing new user and group accounts, these watches will alert the system administrator(s) to any modifications. Any unexpected users, groups, or modifications should be investigated for legitimacy. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - newuidmap |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/bin/newuidmap -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/bin/newuidmap -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify User/Group Information via openat syscall - /etc/passwd |
The audit system should collect write events to /etc/passwd file for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S openat -F a2&03 -F path=/etc/passwd -F auid>=1000 -F auid!=unset -F key=modifyIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S openat -F a2&03 -F path=/etc/passwd -F auid>=1000 -F auid!=unset -F key=modifyIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S openat -F a2&03 -F path=/etc/passwd -F auid>=1000 -F auid!=unset -F key=modify |
Creation of users through direct edition of /etc/passwd could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify User/Group Information via open syscall - /etc/passwd |
The audit system should collect write events to /etc/passwd file for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S open -F a1&03 -F path=/etc/passwd -F auid>=1000 -F auid!=unset -F key=modifyIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S open -F a1&03 -F path=/etc/passwd -F auid>=1000 -F auid!=unset -F key=modifyIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S open -F a1&03 -F path=/etc/passwd -F auid>=1000 -F auid!=unset -F key=modify |
Creation of users through direct edition of /etc/passwd could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - newgrp |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/bin/newgrp -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/bin/newgrp -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify User/Group Information via openat syscall - /etc/shadow |
The audit system should collect write events to /etc/shadow file for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S openat -F a2&03 -F path=/etc/shadow -F auid>=1000 -F auid!=unset -F key=user-modifyIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S openat -F a2&03 -F path=/etc/shadow -F auid>=1000 -F auid!=unset -F key=user-modifyIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S openat -F a2&03 -F path=/etc/shadow -F auid>=1000 -F auid!=unset -F key=user-modify |
Creation of users through direct edition of /etc/shadow could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify User/Group Information via open syscall - /etc/gshadow |
The audit system should collect write events to /etc/gshadow file for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S open -F a1&03 -F path=/etc/gshadow -F auid>=1000 -F auid!=unset -F key=user-modifyIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S open -F a1&03 -F path=/etc/gshadow -F auid>=1000 -F auid!=unset -F key=user-modifyIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S open -F a1&03 -F path=/etc/gshadow -F auid>=1000 -F auid!=unset -F key=user-modify |
Creation of users through direct edition of /etc/gshadow could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify User/Group Information via open_by_handle_at syscall - /etc/gshadow |
The audit system should collect write events to /etc/gshadow file for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S open_by_handle_at -F a2&03 -F path=/etc/gshadow -F auid>=1000 -F auid!=unset -F key=user-modifyIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S open_by_handle_at -F a2&03 -F path=/etc/gshadow -F auid>=1000 -F auid!=unset -F key=user-modifyIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S open_by_handle_at -F a2&03 -F path=/etc/gshadow -F auid>=1000 -F auid!=unset -F key=user-modify |
Creation of users through direct edition of /etc/gshadow could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify User/Group Information via open syscall - /etc/shadow |
The audit system should collect write events to /etc/shadow file for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S open -F a1&03 -F path=/etc/shadow -F auid>=1000 -F auid!=unset -F key=user-modifyIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S open -F a1&03 -F path=/etc/shadow -F auid>=1000 -F auid!=unset -F key=user-modifyIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S open -F a1&03 -F path=/etc/shadow -F auid>=1000 -F auid!=unset -F key=user-modify |
Creation of users through direct edition of /etc/shadow could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AC-2(4) AU-2(d) AU-3 AU-3.1 AU-12(a) AU-12(c) AU-12.1(ii) AU-12.1(iv) AC-6(9) CM-6(a) MA-4(1)(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - unix_chkpwd |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/sbin/unix_chkpwd -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/sbin/unix_chkpwd -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - chsh |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/bin/chsh -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/bin/chsh -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - newgidmap |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/bin/newgidmap -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/bin/newgidmap -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify User/Group Information - /etc/passwd |
If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following lines to a file with suffix .rules in the
directory /etc/audit/rules.d, in order to capture events that modify
account changes:
-w /etc/passwd -p wa -k audit_rules_usergroup_modification If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file, in order to capture events that modify account changes: -w /etc/passwd -p wa -k audit_rules_usergroup_modification |
In addition to auditing new user and group accounts, these watches will alert the system administrator(s) to any modifications. Any unexpected users, groups, or modifications should be investigated for legitimacy. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Any Attempts to Run semanage |
At a minimum, the audit system should collect any execution attempt
of the semanage command for all users and root. If the auditd
daemon is configured to use the augenrules program to read audit rules
during daemon startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/sbin/semanage -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F path=/usr/sbin/semanage -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - usernetctl |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/sbin/usernetctl -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/sbin/usernetctl -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify User/Group Information via open_by_handle_at syscall - /etc/shadow |
The audit system should collect write events to /etc/shadow file for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S open_by_handle_at -F a2&03 -F path=/etc/shadow -F auid>=1000 -F auid!=unset -F key=user-modifyIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S open_by_handle_at -F a2&03 -F path=/etc/shadow -F auid>=1000 -F auid!=unset -F key=user-modifyIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S open_by_handle_at -F a2&03 -F path=/etc/shadow -F auid>=1000 -F auid!=unset -F key=user-modify |
Creation of users through direct edition of /etc/shadow could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify User/Group Information via openat syscall - /etc/group |
The audit system should collect write events to /etc/group file for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S openat -F a2&03 -F path=/etc/group -F auid>=1000 -F auid!=unset -F key=modifyIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S openat -F a2&03 -F path=/etc/group -F auid>=1000 -F auid!=unset -F key=modifyIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S openat -F a2&03 -F path=/etc/group -F auid>=1000 -F auid!=unset -F key=modify |
Creation of groups through direct edition of /etc/group could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify User/Group Information via openat syscall - /etc/gshadow |
The audit system should collect write events to /etc/gshadow file for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S openat -F a2&03 -F path=/etc/gshadow -F auid>=1000 -F auid!=unset -F key=user-modifyIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S openat -F a2&03 -F path=/etc/gshadow -F auid>=1000 -F auid!=unset -F key=user-modifyIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S openat -F a2&03 -F path=/etc/gshadow -F auid>=1000 -F auid!=unset -F key=user-modify |
Creation of users through direct edition of /etc/gshadow could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| AC-2(4) AU-2(d) AU-3 AU-3.1 AU-12(a) AU-12(c) AU-12.1(ii) AU-12.1(iv) AC-6(9) CM-6(a) MA-4(1)(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - unix2_chkpwd |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/sbin/unix2_chkpwd -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/sbin/unix2_chkpwd -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - passwd |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/bin/passwd -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/bin/passwd -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify User/Group Information - /etc/gshadow |
If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following lines to a file with suffix .rules in the
directory /etc/audit/rules.d, in order to capture events that modify
account changes:
-w /etc/gshadow -p wa -k audit_rules_usergroup_modification If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file, in order to capture events that modify account changes: -w /etc/gshadow -p wa -k audit_rules_usergroup_modification |
In addition to auditing new user and group accounts, these watches will alert the system administrator(s) to any modifications. Any unexpected users, groups, or modifications should be investigated for legitimacy. |
| AC-2(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Record Events that Modify User/Group Information via open syscall - /etc/group |
The audit system should collect write events to /etc/group file for all users and root.
If the auditd daemon is configured
to use the augenrules program to read audit rules during daemon
startup (the default), add the following lines to a file with suffix
.rules in the directory /etc/audit/rules.d:
-a always,exit -F arch=b32 -S open -F a1&03 -F path=/etc/group -F auid>=1000 -F auid!=unset -F key=modifyIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: -a always,exit -F arch=b32 -S open -F a1&03 -F path=/etc/group -F auid>=1000 -F auid!=unset -F key=modifyIf the system is 64 bit then also add the following line: -a always,exit -F arch=b64 -S open -F a1&03 -F path=/etc/group -F auid>=1000 -F auid!=unset -F key=modify |
Creation of groups through direct edition of /etc/group could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise. |
| SI-2(5) CM-6(a) SI-2(c) |
Configure dnf-automatic to Install Only Security Updates | To configure dnf-automatic to install only security updates automatically, set upgrade_type to security under [commands] section in /etc/dnf/automatic.conf. | By default, dnf-automatic installs all available updates. Reducing the amount of updated packages only to updates that were issued as a part of a security advisory increases the system stability. |
| AC-2(5) AC-12 AC-17(a) SC-10 CM-6(a) |
Set SSH Client Alive Count Max | The SSH server sends at most ClientAliveCountMax messages during a SSH session and waits for a response from the SSH client. The option ClientAliveInterval configures timeout after each ClientAliveCountMax message. If the SSH server does not receive a response from the client, then the connection is considered unresponsive and terminated. For SSH earlier than v8.2, a ClientAliveCountMax value of 0 causes a timeout precisely when the ClientAliveInterval is set. Starting with v8.2, a value of 0 disables the timeout functionality completely. If the option is set to a number greater than 0, then the session will be disconnected after ClientAliveInterval * ClientAliveCountMax seconds without receiving a keep alive message. | This ensures a user login will be terminated as soon as the ClientAliveInterval is reached. |
| SI-2(5) SI-2(c) CM-6(a) |
Ensure Software Patches Installed |
If the system is joined to the Red Hat Network, a Red Hat Satellite Server,
or a yum server, run the following command to install updates:
$ sudo yum updateIf the system is not configured to use one of these sources, updates (in the form of RPM packages) can be manually downloaded from the Red Hat Network and installed using rpm. NOTE: U.S. Defense systems are required to be patched within 30 days or sooner as local policy dictates. |
Installing software updates is a fundamental mitigation against the exploitation of publicly-known vulnerabilities. If the most recent security patches and updates are not installed, unauthorized users may take advantage of weaknesses in the unpatched software. The lack of prompt attention to patching could result in a system compromise. |
| SI-2(5) CM-6(a) SI-2(c) |
Enable dnf-automatic Timer |
The dnf-automatic timer can be enabled with the following command:
$ sudo systemctl enable dnf-automatic.timer |
The dnf-automatic is an alternative command line interface (CLI) to dnf upgrade with specific facilities to make it suitable to be executed automatically and regularly from systemd timers, cron jobs and similar. The tool is controlled by dnf-automatic.timer SystemD timer. |
| SI-2(5) CM-6(a) SI-2(c) |
Configure dnf-automatic to Install Available Updates Automatically | To ensure that the packages comprising the available updates will be automatically installed by dnf-automatic, set apply_updates to yes under [commands] section in /etc/dnf/automatic.conf. | Installing software updates is a fundamental mitigation against the exploitation of publicly-known vulnerabilities. If the most recent security patches and updates are not installed, unauthorized users may take advantage of weaknesses in the unpatched software. The lack of prompt attention to patching could result in a system compromise. The automated installation of updates ensures that recent security patches are applied in a timely manner. |
| AC-2(5) AC-12 AC-17(a) SC-10 CM-6(a) |
Set SSH Client Alive Count Max to zero | The SSH server sends at most ClientAliveCountMax messages during a SSH session and waits for a response from the SSH client. The option ClientAliveInterval configures timeout after each ClientAliveCountMax message. If the SSH server does not receive a response from the client, then the connection is considered unresponsive and terminated. To ensure the SSH timeout occurs precisely when the ClientAliveInterval is set, set the ClientAliveCountMax to value of 0 in /etc/ssh/sshd_config: | This ensures a user login will be terminated as soon as the ClientAliveInterval is reached. |
| SI-2(6) CM-11(a) CM-11(b) CM-6(a) |
Ensure yum Removes Previous Package Versions | yum should be configured to remove previous software components after new versions have been installed. To configure yum to remove the previous software components after updating, set the clean_requirements_on_remove to 1 in /etc/yum.conf. | Previous versions of software components that are not removed from the information system after updates have been installed may be exploited by some adversaries. |
| AC-2(7)(b) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
Ensure auditd Collects System Administrator Actions |
At a minimum, the audit system should collect administrator actions
for all users and root. If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the default),
add the following line to a file with suffix .rules in the directory
/etc/audit/rules.d:
-w /etc/sudoers -p wa -k actions -w /etc/sudoers.d/ -p wa -k actionsIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file: -w /etc/sudoers -p wa -k actions -w /etc/sudoers.d/ -p wa -k actions |
The actions taken by system administrators should be audited to keep a record of what was executed on the system, as well as, for accountability purposes. |
| IA-2(11) | Certificate status checking in SSSD | Multifactor solutions that require devices separate from information systems gaining access include, for example, hardware tokens providing time-based or challenge-response authenticators and smart cards. Configuring certificate_verification to ocsp_dgst=sha1 ensures that certificates for multifactor solutions are checked via Online Certificate Status Protocol (OCSP). | Ensuring that multifactor solutions certificates are checked via Online Certificate Status Protocol (OCSP) ensures the security of the system. |
| AC-3 CM-6(a) |
Limit Users' SSH Access | By default, the SSH configuration allows any user with an account to access the system. There are several options available to limit which users and group can access the system via SSH. It is recommended that at least one of the following options be leveraged: - AllowUsers variable gives the system administrator the option of allowing specific users to ssh into the system. The list consists of space separated user names. Numeric user IDs are not recognized with this variable. If a system administrator wants to restrict user access further by specifically allowing a user's access only from a particular host, the entry can be specified in the form of user@host. - AllowGroups variable gives the system administrator the option of allowing specific groups of users to ssh into the system. The list consists of space separated group names. Numeric group IDs are not recognized with this variable. - DenyUsers variable gives the system administrator the option of denying specific users to ssh into the system. The list consists of space separated user names. Numeric user IDs are not recognized with this variable. If a system administrator wants to restrict user access further by specifically denying a user's access from a particular host, the entry can be specified in the form of user@host. - DenyGroups variable gives the system administrator the option of denying specific groups of users to ssh into the system. The list consists of space separated group names. Numeric group IDs are not recognized with this variable. | Specifying which accounts are allowed SSH access into the system reduces the possibility of unauthorized access to the system. |
| AC-3 AC-3.1 AC-3 |
Set the UEFI Boot Loader Password - systems prior to version 7.2 |
The grub2 boot loader should have a superuser account and password
protection enabled to protect boot-time settings.
Since plaintext passwords are a security risk, generate a hash for the password by running the following command: # grub2-mkpasswd-pbkdf2When prompted, enter the password that was selected. Using the hash from the output, modify the /etc/grub.d/40_custom file with the following content: set superusers="root" password_pbkdf2 boot grub.pbkdf2.sha512.VeryLongStringOnce the superuser password has been added, update the grub.cfg file by running: grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg |
Password protection on the boot loader configuration ensures users with physical access cannot trivially alter important bootloader settings. These include which kernel to use, and whether to enter single-user mode. |
| AU-3 AU-3.1 AU-12(a) AU-12.1(ii) AU-12.1(iv)AU-12(c) MA-4(1)(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - kmod |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/bin/kmod -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/bin/kmod -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). |
| AC-3 MP-2 |
Verify Group Who Owns /etc/shells File |
To properly set the group owner of /etc/shells, run the command:
$ sudo chgrp root /etc/shells |
The /etc/shells file contains the list of full pathnames to shells on the system. Since this file is used by many system programs this file should be protected. |
| AC-3 | Enable authselect | Configure user authentication setup to use the authselect tool. If authselect profile is selected, the rule will enable the minimal profile. | Authselect is a successor to authconfig. It is a tool to select system authentication and identity sources from a list of supported profiles instead of letting the administrator manually build the PAM stack. That way, it avoids potential breakage of configuration, as it ships several tested profiles that are well tested and supported to solve different use-cases. |
| AC-3 AC-3(3)(a) |
Ensure SELinux Not Disabled in /etc/default/grub | SELinux can be disabled at boot time by an argument in /etc/default/grub. Remove any instances of selinux=0 from the kernel arguments in that file to prevent SELinux from being disabled at boot. | Disabling a major host protection feature, such as SELinux, at boot time prevents it from confining system services at boot time. Further, it increases the chances that it will remain off during system operation. |
| AC-3 AC-3(3)(a) AU-9 SC-7(21) |
Ensure SELinux State is Enforcing |
The SELinux state should be set to enforcing at
system boot time. In the file /etc/selinux/config, add or correct the
following line to configure the system to boot into enforcing mode:
SELINUX=enforcing |
Setting the SELinux state to enforcing ensures SELinux is able to confine potentially compromised processes to the security policy, which is designed to prevent them from causing damage to the system or further elevating their privileges. |
| AC-3 MP-2 |
Verify Who Owns /etc/shells File |
To properly set the owner of /etc/shells, run the command:
$ sudo chown root /etc/shells |
The /etc/shells file contains the list of full pathnames to shells on the system. Since this file is used by many system programs this file should be protected. |
| AC-3 MP-2 |
Verify Permissions on /etc/shells File |
To properly set the permissions of /etc/shells, run the command:
$ sudo chmod 0644 /etc/shells |
The /etc/shells file contains the list of full pathnames to shells on the system. Since this file is used by many system programs this file should be protected. |
| AU-3 AU-12(a) AU-12(c) MA-4(1)(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - chfn |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/bin/chfn -F perm=x -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/bin/chfn -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged |
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). |
| AC-3 AC-3(3)(a) AU-9 SC-7(21) |
Configure SELinux Policy |
The SELinux targeted policy is appropriate for
general-purpose desktops and servers, as well as systems in many other roles.
To configure the system to use this policy, add or correct the following line
in /etc/selinux/config:
SELINUXTYPE=targetedOther policies, such as mls, provide additional security labeling and greater confinement but are not compatible with many general-purpose use cases. |
Setting the SELinux policy to targeted or a more specialized policy
ensures the system will confine processes that are likely to be
targeted for exploitation, such as network or system services.
Note: During the development or debugging of SELinux modules, it is common to temporarily place non-production systems in permissive mode. In such temporary cases, SELinux policies should be developed, and once work is completed, the system should be reconfigured to . |
| AC-3 AC-3.1 AC-3 |
Set Boot Loader Password in grub2 - systems prior to version 7.2 |
The grub2 boot loader should have a superuser account and password
protection enabled to protect boot-time settings.
Since plaintext passwords are a security risk, generate an encrypted grub2 password for the grub superusers with the following command: $ grub2-mkpasswd-pbkdf2When prompted, enter the password that was selected. Using the hash from the output, modify the /etc/grub.d/40_custom file with the following content: set superusers="root" password_pbkdf2 root grub.pbkdf2.sha512.VeryLongStringOnce the superuser password has been added, update the grub.cfg file by running: grub2-mkconfig -o /boot/grub2/grub.cfg |
Password protection on the boot loader configuration ensures users with physical access cannot trivially alter important bootloader settings. These include which kernel to use, and whether to enter single-user mode. |
| AC-3 AC-17(a) CM-7(a) CM-7(b) CM-6(a) |
Disable Host-Based Authentication |
SSH's cryptographic host-based authentication is
more secure than .rhosts authentication. However, it is
not recommended that hosts unilaterally trust one another, even
within an organization.
The default SSH configuration disables host-based authentication. The appropriate configuration is used if no value is set for HostbasedAuthentication. To explicitly disable host-based authentication, add or correct the following line in /etc/ssh/sshd_config: HostbasedAuthentication no |
SSH trust relationships mean a compromise on one host can allow an attacker to move trivially to other hosts. |
| AC-3 AC-3(3)(a) |
Ensure SELinux Not Disabled in the kernel arguments | SELinux can be disabled at boot time by disabling it via a kernel argument. Remove any instances of selinux=0 from the kernel arguments in that file to prevent SELinux from being disabled at boot. | Disabling a major host protection feature, such as SELinux, at boot time prevents it from confining system services at boot time. Further, it increases the chances that it will remain off during system operation. |
| AC-3(4) AC-6(10) |
Elevate The SELinux Context When An Administrator Calls The Sudo Command |
Configure the operating system to elevate the SELinux context when an administrator calls
the sudo command.
Edit a file in the /etc/sudoers.d directory with the following command:
sudo visudo -f /etc/sudoers.d/CUSTOM_FILEUse the following example to build the CUSTOM_FILE in the /etc/sudoers.d directory to allow any administrator belonging to a designated sudoers admin group to elevate their SELinux context with the use of the sudo command: %wheel ALL=(ALL) TYPE=sysadm_t ROLE=sysadm_r ALL |
Preventing non-privileged users from executing privileged functions mitigates
the risk that unauthorized individuals or processes may gain unnecessary access
to information or privileges.
Privileged functions include, for example, establishing accounts, performing system integrity checks, or administering cryptographic key management activities. Non-privileged users are individuals who do not possess appropriate authorizations. Circumventing intrusion detection and prevention mechanisms or malicious code protection mechanisms are examples of privileged functions that require protection from non-privileged users. |
| AC-3(4) AC-6(8) AC-6(10) CM-7(5)(b) CM-7(2) SC-7(21) CM-6(a) |
Install the pam_apparmor Package |
The pam_apparmor package can be installed with the following command:
$ sudo yum install pam_apparmor |
Protection of system integrity using AppArmor depends on this package being installed. |
| AC-3(4) AC-6(8) AC-6(10) CM-7(5)(b) CM-7(2) SC-7(21) CM-6(a) |
Ensure AppArmor is Active and Configured |
Verify that the Apparmor tool is configured to
control whitelisted applications and user home directory access
control. The apparmor service can be enabled with the following command:
$ sudo systemctl enable apparmor.service |
Using a whitelist provides a configuration management method for allowing
the execution of only authorized software. Using only authorized software
decreases risk by limiting the number of potential vulnerabilities. The organization must identify authorized software programs and permit execution of authorized software by adding each authorized program to the "pam_apparmor" exception policy. The process used to identify software programs that are authorized to execute on organizational information systems is commonly referred to as whitelisting. Verification of whitelisted software occurs prior to execution or at system startup. Users' home directories/folders may contain information of a sensitive nature. Nonprivileged users should coordinate any sharing of information with a System Administrator (SA) through shared resources. Apparmor can confine users to their home directory, not allowing them to make any changes outside of their own home directories. Confining users to their home directory will minimize the risk of sharing information. |
| AC-3(4) AC-6(10) |
Confine SELinux Users To Roles That Conform To Least Privilege |
Configure the operating system to confine SELinux users to roles that conform
to least privilege. Use the following command to map the "staff_u" SELinux user
to the "staff_r" and "sysadm_r" roles:
$ sudo semanage user -m staff_u -R staff_r -R sysadm_r Use the following command to map the "user_u" SELinux user to the "user_r" role: $ sudo semanage -m user_u -R user_r |
Preventing non-privileged users from executing privileged functions mitigates
the risk that unauthorized individuals or processes may gain unnecessary access
to information or privileges.
Privileged functions include, for example, establishing accounts, performing system integrity checks, or administering cryptographic key management activities. Non-privileged users are individuals who do not possess appropriate authorizations. Circumventing intrusion detection and prevention mechanisms or malicious code protection mechanisms are examples of privileged functions that require protection from non-privileged users. |
| CA-3(5) CM-7(b) SC-7(23) CM-6(a) |
Set Default iptables Policy for Forwarded Packets |
To set the default policy to DROP (instead of ACCEPT) for
the built-in FORWARD chain which processes packets that will be forwarded from
one interface to another,
add or correct the following line in
/etc/sysconfig/iptables:
:FORWARD DROP [0:0] |
In iptables, the default policy is applied only after all the applicable rules in the table are examined for a match. Setting the default policy to DROP implements proper design for a firewall, i.e. any packets which are not explicitly permitted should not be accepted. |
| CM-3(5) | The s-nail Package Is Installed |
A mail server is required for sending emails.
The s-nail package can be installed with the following command:
$ sudo yum install s-nail |
Emails can be used to notify designated personnel about important system events such as failures or warnings. |
| CA-3(5) CM-7(b) SC-7(23) CM-6(a) |
Set Default firewalld Zone for Incoming Packets |
To set the default zone to drop for
the built-in default zone which processes incoming IPv4 and IPv6 packets,
modify the following line in
/etc/firewalld/firewalld.conf to be:
DefaultZone=drop |
In firewalld the default zone is applied only after all the applicable rules in the table are examined for a match. Setting the default zone to drop implements proper design for a firewall, i.e. any packets which are not explicitly permitted should not be accepted. |
| CM-3(5) | The mailx Package Is Installed |
A mail server is required for sending emails.
The mailx package can be installed with the following command:
$ sudo yum install mailx |
Emails can be used to notify designated personnel about important system events such as failures or warnings. |
| CA-3(5) CM-7(b) SC-7(23) CM-6(a) |
Set Default iptables Policy for Incoming Packets |
To set the default policy to DROP (instead of ACCEPT) for
the built-in INPUT chain which processes incoming packets,
add or correct the following line in
/etc/sysconfig/iptables:
:INPUT DROP [0:0] |
In iptables the default policy is applied only after all the applicable rules in the table are examined for a match. Setting the default policy to DROP implements proper design for a firewall, i.e. any packets which are not explicitly permitted should not be accepted. |
| CM-3(6) SC-12(2) SC-12(3) IA-7 SC-13 CM-6(a) SC-12 |
Enable FIPS Mode |
To enable FIPS mode, run the following command:
fips-mode-setup --enable The fips-mode-setup command will configure the system in FIPS mode by automatically configuring the following:
|
Use of weak or untested encryption algorithms undermines the purposes of utilizing encryption to protect data. The operating system must implement cryptographic modules adhering to the higher standards approved by the federal government since this provides assurance they have been tested and validated. |
| CM-3(6) IA-2(4) |
Disable SSH Server If Possible | The SSH server service, sshd, is commonly needed. However, if it can be disabled, do so. This is unusual, as SSH is a common method for encrypted and authenticated remote access. | |
| AC-4 CM-7(b) CA-3(5) SC-7(21) CM-6(a) |
Verify iptables Enabled |
The iptables service can be enabled with the following command:
$ sudo systemctl enable iptables.service |
The iptables service provides the system's host-based firewalling capability for IPv4 and ICMP. |
| AC-4 CM-7(b) CA-3(5) SC-7(21) CM-6(a) |
Verify ip6tables Enabled if Using IPv6 |
The ip6tables service can be enabled with the following command:
$ sudo systemctl enable ip6tables.service |
The ip6tables service provides the system's host-based firewalling capability for IPv6 and ICMPv6. |
| AC-4 CM-7(a) CM-7(b) CM-6(a) |
Disable Network Router Discovery Daemon (rdisc) |
The rdisc service implements the client side of the ICMP
Internet Router Discovery Protocol (IRDP), which allows discovery of routers on
the local subnet. If a router is discovered then the local routing table is
updated with a corresponding default route. By default this daemon is disabled.
The rdisc service can be disabled with the following command:
$ sudo systemctl mask --now rdisc.service |
General-purpose systems typically have their network and routing information configured statically by a system administrator. Workstations or some special-purpose systems often use DHCP (instead of IRDP) to retrieve dynamic network configuration information. |
| AC-4 CM-7(b) CA-3(5) SC-7(21) CM-6(a) |
Set Default ip6tables Policy for Incoming Packets |
To set the default policy to DROP (instead of ACCEPT) for
the built-in INPUT chain which processes incoming packets,
add or correct the following line in
/etc/sysconfig/ip6tables:
:INPUT DROP [0:0]If changes were required, reload the ip6tables rules: $ sudo service ip6tables reload |
In ip6tables, the default policy is applied only after all the applicable rules in the table are examined for a match. Setting the default policy to DROP implements proper design for a firewall, i.e. any packets which are not explicitly permitted should not be accepted. |
| IA-4(e) | Set Account Expiration Following Inactivity in system-auth |
Verify the account identifiers (individuals, groups, roles, and devices) are disabled after
35 or less days of inactivity by
checking the account inactivity value with the following command:
grep 'inactive\|pam_unix' /etc/pam.d/password-auth | grep -w auth auth required pam_lastlog.so inactive=35 auth sufficient pam_unix.soThe line with the inactive parameter should be placed before pam_unix.so module as in the example output. |
Inactive identifiers pose a risk to systems and applications because attackers may exploit an inactive identifier and potentially obtain undetected access to the system. Owners of inactive accounts will not notice if unauthorized access to their user account has been obtained. |
| AC-4 CM-7(b) CA-3(5) SC-7(21) CM-6(a) |
Verify firewalld Enabled |
The firewalld service can be enabled with the following command:
$ sudo systemctl enable firewalld.service |
Access control methods provide the ability to enhance system security posture by restricting services and known good IP addresses and address ranges. This prevents connections from unknown hosts and protocols. |
| IA-4(e) AC-2(3) CM-6(a) |
Set existing passwords a period of inactivity before they been locked |
Configure user accounts that have been inactive for over a given period of time
to be automatically disabled by running the following command:
$ sudo chage --inactive 30USER |
Inactive accounts pose a threat to system security since the users are not logging in to notice failed login attempts or other anomalies. |
| IA-4(e) | Set Account Expiration Following Inactivity in password-auth |
Verify the account identifiers (individuals, groups, roles, and devices) are disabled after
35 or less days of inactivity by
checking the account inactivity value with the following command:
grep 'inactive\|pam_unix' /etc/pam.d/password-auth | grep -w auth auth required pam_lastlog.so inactive=35 auth sufficient pam_unix.soThe line with the inactive parameter should be placed before pam_unix.so module as in the example output. |
Inactive identifiers pose a risk to systems and applications because attackers may exploit an inactive identifier and potentially obtain undetected access to the system. Owners of inactive accounts will not notice if unauthorized access to their user account has been obtained. |
| AC-4 CM-7(b) CA-3(5) SC-7(21) CM-6(a) |
Configure the Firewalld Ports |
Configure the firewalld ports to allow approved services to have access to the system.
To configure firewalld to open ports, run the following command:
firewall-cmd --permanent --add-port=port_number/tcpTo configure firewalld to allow access for pre-defined services, run the following command: firewall-cmd --permanent --add-service=service_name |
In order to prevent unauthorized connection of devices, unauthorized transfer of information,
or unauthorized tunneling (i.e., embedding of data types within data types), organizations must
disable or restrict unused or unnecessary physical and logical ports/protocols on information
systems.
Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services provided by default may not be necessary to support essential organizational operations. Additionally, it is sometimes convenient to provide multiple services from a single component (e.g., VPN and IPS); however, doing so increases risk over limiting the services provided by one component. To support the requirements and principles of least functionality, the operating system must support the organizational requirements, providing only essential capabilities and limiting the use of ports, protocols, and/or services to only those required, authorized, and approved to conduct official business. |
| IA-4(e) AC-2(3) CM-6(a) |
Set Account Expiration Following Inactivity |
To specify the number of days after a password expires (which
signifies inactivity) until an account is permanently disabled, add or correct
the following line in /etc/default/useradd:
INACTIVE=35If a password is currently on the verge of expiration, then 35 day(s) remain(s) until the account is automatically disabled. However, if the password will not expire for another 60 days, then 60 days plus 35 day(s) could elapse until the account would be automatically disabled. See the useradd man page for more information. |
Inactive identifiers pose a risk to systems and applications because attackers may exploit an inactive identifier and potentially obtain undetected access to the system. Disabling inactive accounts ensures that accounts which may not have been responsibly removed are not available to attackers who may have compromised their credentials. Owners of inactive accounts will not notice if unauthorized access to their user account has been obtained. |
| AU-4(1) | Ensure Rsyslog Encrypts Off-Loaded Audit Records |
Rsyslogd is a system utility providing support for message logging. Support
for both internet and UNIX domain sockets enables this utility to support both local
and remote logging. Couple this utility with gnutls (which is a secure communications
library implementing the SSL, TLS and DTLS protocols), and you have a method to securely
encrypt and off-load auditing.
When using rsyslogd to off-load logs off a encrpytion system must be used.
Set the following configuration option in /etc/rsyslog.conf or in a file in /etc/rsyslog.d (using legacy syntax):
$ActionSendStreamDriverMode 1Alternatively, use the RainerScript syntax: action(type="omfwd" ... StreamDriverMode="1") |
The audit records generated by Rsyslog contain valuable information regarding system configuration, user authentication, and other such information. Audit records should be protected from unauthorized access. |
| AU-4(1) CM-6(a) |
Configure auditd to use audispd's syslog plugin |
To configure the auditd service to use the
syslog plug-in of the audispd audit event multiplexor, set
the active line in /etc/audit/plugins.d/syslog.conf to yes.
Restart the auditd service:
$ sudo service auditd restart |
The auditd service does not include the ability to send audit records to a centralized server for management directly. It does, however, include a plug-in for audit event multiplexor (audispd) to pass audit records to the local syslog server. |
| AU-4(1) | Ensure Rsyslog Authenticates Off-Loaded Audit Records |
Rsyslogd is a system utility providing support for message logging. Support
for both internet and UNIX domain sockets enables this utility to support both local
and remote logging. Couple this utility with gnutls (which is a secure communications
library implementing the SSL, TLS and DTLS protocols), and you have a method to securely
encrypt and off-load auditing.
When using rsyslogd to off-load logs the remote system must be authenticated.
Set the following configuration option in /etc/rsyslog.conf or in a file in /etc/rsyslog.d (using legacy syntax):
$ActionSendStreamDriverAuthMode x509/nameAlternatively, use the RainerScript syntax: action(type="omfwd" Target="some.example.com" StreamDriverAuthMode="x509/name") |
The audit records generated by Rsyslog contain valuable information regarding system configuration, user authentication, and other such information. Audit records should be protected from unauthorized access. |
| AU-4(1) | Appropriate Action Must be Setup When the Internal Audit Event Queue is Full | The audit system should have an action setup in the event the internal event queue becomes full. To setup an overflow action edit /etc/audit/auditd.conf. Set overflow_action to one of the following values: syslog, single, halt. | The audit system should have an action setup in the event the internal event queue becomes full so that no data is lost. |
| AU-4(1) | Ensure Rsyslog Encrypts Off-Loaded Audit Records |
Rsyslogd is a system utility providing support for message logging. Support
for both internet and UNIX domain sockets enables this utility to support both local
and remote logging. Couple this utility with gnutls (which is a secure communications
library implementing the SSL, TLS and DTLS protocols), and you have a method to securely
encrypt and off-load auditing.
When using rsyslogd to off-load logs off an encryption system must be used.
Set the following configuration option in /etc/rsyslog.conf or in a file in /etc/rsyslog.d (using legacy syntax):
$DefaultNetstreamDriver gtlsAlternatively, use the RainerScript syntax: global(DefaultNetstreamDriver="gtls") |
The audit records generated by Rsyslog contain valuable information regarding system configuration, user authentication, and other such information. Audit records should be protected from unauthorized access. |
| SC-5 | Configure Firewalld to Use the Nftables Backend | Firewalld can be configured with many backends, such as nftables. | Nftables is modern kernel module for controling network connections coming into a system. Utilizing the limit statement in "nftables" can help to mitigate DoS attacks. |
| AU-5(b) AU-5(2) AU-5(1) AU-5(4) CM-6(a) |
Configure auditd max_log_file_action Upon Reaching Maximum Log Size |
The default action to take when the logs reach their maximum size
is to rotate the log files, discarding the oldest one. To configure the action taken
by auditd, add or correct the line in /etc/audit/auditd.conf:
max_log_file_action = ACTIONPossible values for ACTION are described in the auditd.conf man page. These include:
|
Automatically rotating logs (by setting this to rotate) minimizes the chances of the system unexpectedly running out of disk space by being overwhelmed with log data. However, for systems that must never discard log data, or which use external processes to transfer it and reclaim space, keep_logs can be employed. |
| AU-5(b) AU-5(2) AU-5(1) AU-5(4) CM-6(a) |
Configure auditd max_log_file_action Upon Reaching Maximum Log Size |
The default action to take when the logs reach their maximum size
is to rotate the log files, discarding the oldest one. To configure the action taken
by auditd, add or correct the line in /etc/audit/auditd.conf:
max_log_file_action = ACTIONPossible values for ACTION are described in the auditd.conf man page. These include:
|
Automatically rotating logs (by setting this to rotate) minimizes the chances of the system unexpectedly running out of disk space by being overwhelmed with log data. However, for systems that must never discard log data, or which use external processes to transfer it and reclaim space, keep_logs can be employed. |
| AU-5(b) AU-5(2) AU-5(1) AU-5(4) CM-6(a) |
Configure audispd's Plugin network_failure_action On Network Failure |
Configure the action the operating system takes if there is an error sending
audit records to a remote system. Edit the file /etc/audit/audisp-remote.conf.
Add or modify the following line, substituting ACTION appropriately:
network_failure_action = ACTIONSet this value to single to cause the system to switch to single user mode for corrective action. Acceptable values also include syslog and halt. For certain systems, the need for availability outweighs the need to log all actions, and a different setting should be determined. This profile configures the action to be single. |
Taking appropriate action when there is an error sending audit records to a remote system will minimize the possibility of losing audit records. |
| AU-5(b) AU-5(2) AU-5(1) AU-5(4) CM-6(a) |
Configure auditd Disk Error Action on Disk Error |
The auditd service can be configured to take an action
when there is a disk error.
Edit the file /etc/audit/auditd.conf. Add or modify the following line,
substituting ACTION appropriately:
disk_error_action = ACTIONSet this value to single to cause the system to switch to single-user mode for corrective action. Acceptable values also include syslog, exec, single, and halt. For certain systems, the need for availability outweighs the need to log all actions, and a different setting should be determined. Details regarding all possible values for ACTION are described in the auditd.conf man page. |
Taking appropriate action in case of disk errors will minimize the possibility of losing audit records. |
| AU-5(b) AU-5(2) AU-5(1) AU-5(4) CM-6(a) |
Configure auditd Disk Full Action when Disk Space Is Full |
The auditd service can be configured to take an action
when disk space is running low but prior to running out of space completely.
Edit the file /etc/audit/auditd.conf. Add or modify the following line,
substituting ACTION appropriately:
disk_full_action = ACTIONSet this value to single to cause the system to switch to single-user mode for corrective action. Acceptable values also include syslog, exec, single, and halt. For certain systems, the need for availability outweighs the need to log all actions, and a different setting should be determined. Details regarding all possible values for ACTION are described in the auditd.conf man page. |
Taking appropriate action in case of a filled audit storage volume will minimize the possibility of losing audit records. |
| AU-5(b) AU-5(2) AU-5(1) AU-5(4) CM-6(a) |
Configure auditd space_left on Low Disk Space |
The auditd service can be configured to take an action
when disk space is running low but prior to running out of space completely.
Edit the file /etc/audit/auditd.conf. Add or modify the following line,
substituting PERCENTAGE appropriately:
space_left = PERCENTAGE%Set this value to at least 25 to cause the system to notify the user of an issue. |
Notifying administrators of an impending disk space problem may allow them to take corrective action prior to any disruption. |
| AU-5(a) AU-5.1(ii) |
Configure System to Forward All Mail From Postmaster to The Root Account |
Verify the administrators are notified in the event of an audit processing failure.
Check that the "/etc/aliases" file has a defined value for "root".
$ sudo grep "postmaster:\s*root$" /etc/aliases postmaster: root |
It is critical for the appropriate personnel to be aware if a system is at risk of failing to process audit logs as required. Without this notification, the security personnel may be unaware of an impending failure of the audit capability, and system operation may be adversely affected. Audit processing failures include software/hardware errors, failures in the audit capturing mechanisms, and audit storage capacity being reached or exceeded. |
| IA-5(a) IA-5(v) |
Set Password Strength Minimum Special Characters | The pam_cracklib module's ocredit= parameter controls requirements for usage of special (or ``other'') characters in a password. When set to a negative number, any password will be required to contain that many special characters. When set to a positive number, pam_cracklib will grant +1 additional length credit for each special character. Make sure the ocredit parameter for the pam_cracklib module is set to less than or equal to -1. For example, ocredit=-1. | Requiring a minimum number of special characters makes password guessing attacks more difficult by ensuring a larger search space. |
| IA-5(c) IA-5(1)(a) CM-6(a) IA-5(4) |
Ensure PAM Enforces Password Requirements - Minimum Uppercase Characters | The pam_pwquality module's ucredit= parameter controls requirements for usage of uppercase letters in a password. When set to a negative number, any password will be required to contain that many uppercase characters. When set to a positive number, pam_pwquality will grant +1 additional length credit for each uppercase character. Modify the ucredit setting in /etc/security/pwquality.conf to require the use of an uppercase character in passwords. |
Use of a complex password helps to increase the time and resources required to compromise the password.
Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts
at guessing and brute-force attacks.
Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised. |
| AU-5(b) SC-24 CM-6(a) |
Shutdown System When Auditing Failures Occur |
If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following line to to the bottom of a file with suffix
.rules in the directory /etc/audit/rules.d:
-f 2If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to the bottom of the /etc/audit/audit.rules file: -f 2 |
It is critical for the appropriate personnel to be aware if a system
is at risk of failing to process audit logs as required. Without this
notification, the security personnel may be unaware of an impending failure of
the audit capability, and system operation may be adversely affected.
Audit processing failures include software/hardware errors, failures in the audit capturing mechanisms, and audit storage capacity being reached or exceeded. |
| IA-5(f) IA-5(1)(a) CM-6(a) |
Set Password Minimum Length in login.defs |
To specify password length requirements for new accounts, edit the file
/etc/login.defs and add or correct the following line:
PASS_MIN_LEN 15 The DoD requirement is 15. The FISMA requirement is 12. The profile requirement is 15. If a program consults /etc/login.defs and also another PAM module (such as pam_pwquality) during a password change operation, then the most restrictive must be satisfied. See PAM section for more information about enforcing password quality requirements. |
Requiring a minimum password length makes password cracking attacks more difficult by ensuring a larger search space. However, any security benefit from an onerous requirement must be carefully weighed against usability problems, support costs, or counterproductive behavior that may result. |
| AU-5(b) AU-5(2) AU-5(1) AU-5(4) CM-6(a) |
Configure auditd Disk Full Action when Disk Space Is Full |
The auditd service can be configured to take an action
when disk space is running low but prior to running out of space completely.
Edit the file /etc/audit/auditd.conf. Add or modify the following line,
substituting ACTION appropriately:
disk_full_action = ACTIONSet this value to single to cause the system to switch to single-user mode for corrective action. Acceptable values also include syslog, single, and halt. For certain systems, the need for availability outweighs the need to log all actions, and a different setting should be determined. Details regarding all possible values for ACTION are described in the auditd.conf man page. |
Taking appropriate action in case of a filled audit storage volume will minimize the possibility of losing audit records. |
| IA-5 (2) (a) | SSSD Has a Correct Trust Anchor | SSSD must have acceptable trust anchor present. | Without path validation, an informed trust decision by the relying party cannot be made when presented with any certificate not already explicitly trusted. A trust anchor is an authoritative entity represented via a public key and associated data. It is used in the context of public key infrastructures, X.509 digital certificates, and DNSSEC. When there is a chain of trust, usually the top entity to be trusted becomes the trust anchor; it can be, for example, a Certification Authority (CA). A certification path starts with the subject certificate and proceeds through a number of intermediate certificates up to a trusted root certificate, typically issued by a trusted CA. This requirement verifies that a certification path to an accepted trust anchor is used for certificate validation and that the path includes status information. Path validation is necessary for a relying party to make an informed trust decision when presented with any certificate not already explicitly trusted. Status information for certification paths includes certificate revocation lists or online certificate status protocol responses. Validation of the certificate status information is out of scope for this requirement. |
| IA-5(f) IA-5(1)(d) CM-6(a) |
Set Existing Passwords Maximum Age |
Configure non-compliant accounts to enforce a 60-day maximum password lifetime
restriction by running the following command:
$ sudo chage -M 60 USER |
Any password, no matter how complex, can eventually be cracked. Therefore, passwords need to be changed periodically. If the operating system does not limit the lifetime of passwords and force users to change their passwords, there is the risk that the operating system passwords could be compromised. |
| AU-5(b) AU-5(2) AU-5(1) AU-5(4) CM-6(a) |
Configure auditd admin_space_left Action on Low Disk Space |
The auditd service can be configured to take an action
when disk space is running low but prior to running out of space completely.
Edit the file /etc/audit/auditd.conf. Add or modify the following line,
substituting ACTION appropriately:
admin_space_left_action = ACTIONSet this value to single to cause the system to switch to single user mode for corrective action. Acceptable values also include suspend and halt. For certain systems, the need for availability outweighs the need to log all actions, and a different setting should be determined. Details regarding all possible values for ACTION are described in the auditd.conf man page. |
Administrators should be made aware of an inability to record audit records. If a separate partition or logical volume of adequate size is used, running low on space for audit records should never occur. |
| IA-5 (2) (c) | Enable Certmap in SSSD |
SSSD should be configured to verify the certificate of the user or group. To set this up
ensure that section like certmap/testing.test/rule_name is setup in
/etc/sssd/sssd.conf. For example
[certmap/testing.test/rule_name]
matchrule =<SAN>.*EDIPI@mil
maprule = (userCertificate;binary={cert!bin})
domains = testing.test
|
Without mapping the certificate used to authenticate to the user account, the ability to determine the identity of the individual user or group will not be available for forensic analysis. |
| IA-5(c) IA-5(1)(a) CM-6(a) IA-5(4) |
Ensure PAM Enforces Password Requirements - Minimum Special Characters | The pam_pwquality module's ocredit= parameter controls requirements for usage of special (or "other") characters in a password. When set to a negative number, any password will be required to contain that many special characters. When set to a positive number, pam_pwquality will grant +1 additional length credit for each special character. Modify the ocredit setting in /etc/security/pwquality.conf to equal -1 to require use of a special character in passwords. |
Use of a complex password helps to increase the time and resources required
to compromise the password. Password complexity, or strength, is a measure of
the effectiveness of a password in resisting attempts at guessing and brute-force
attacks.
Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised. Requiring a minimum number of special characters makes password guessing attacks more difficult by ensuring a larger search space. |
| IA-5(f) IA-5(1)(e) |
Limit Password Reuse | Do not allow users to reuse recent passwords. This can be accomplished by using the remember option for the pam_unix or pam_pwhistory PAM modules. | Preventing re-use of previous passwords helps ensure that a compromised password is not re-used by a user. |
| SC-5 | Configure Kernel to Rate Limit Sending of Duplicate TCP Acknowledgments |
Make sure that the system is configured to limit the maximal rate for sending
duplicate acknowledgments in response to incoming TCP packets that are for
an existing connection but that are invalid due to any of these reasons:
(a) out-of-window sequence number, (b) out-of-window acknowledgment number,
or (c) PAWS (Protection Against Wrapped Sequence numbers) check failure
This measure protects against or limits effects of DoS attacks against the system.
Set the system to implement rate-limiting measures by adding the following line to
/etc/sysctl.conf or a configuration file in the /etc/sysctl.d/ directory
(or modify the line to have the required value):
net.ipv4.tcp_invalid_ratelimit = 500Issue the following command to make the changes take effect: # sysctl --system |
Denial of Service (DoS) is a condition when a resource is not available for legitimate users. When
this occurs, the organization either cannot accomplish its mission or must
operate at degraded capacity.
This can help mitigate simple “ack loop” DoS attacks, wherein a buggy or malicious middlebox or man-in-the-middle can rewrite TCP header fields in manner that causes each endpoint to think that the other is sending invalid TCP segments, thus causing each side to send an unterminating stream of duplicate acknowledgments for invalid segments. |
| IA-5(c) IA-5(1)(c) CM-6(a) |
Set PAM''s Password Hashing Algorithm - password-auth |
The PAM system service can be configured to only store encrypted representations of passwords.
In /etc/pam.d/password-auth, the password section of the file controls which
PAM modules to execute during a password change.
Set the pam_unix.so module in the password section to include the option
sha512 and no other hashing
algorithms as shown below:
password sufficient pam_unix.so sha512 other arguments... This will help ensure that new passwords for local users will be stored using the sha512 algorithm. |
Passwords need to be protected at all times, and encryption is the standard method for
protecting passwords. If passwords are not encrypted, they can be plainly read
(i.e., clear text) and easily compromised. Passwords that are encrypted with a weak algorithm
are no more protected than if they are kept in plain text.
This setting ensures user and group account administration utilities are configured to store only encrypted representations of passwords. Additionally, the crypt_style configuration option in /etc/libuser.conf ensures the use of a strong hashing algorithm that makes password cracking attacks more difficult. |
| IA-5(e) | Ensure Default SNMP Password Is Not Used |
Edit /etc/snmp/snmpd.conf, remove or change the default community strings of
public and private.
This profile configures new read-only community string to changemero and read-write community string to changemerw.
Once the default community strings have been changed, restart the SNMP service:
$ sudo systemctl restart snmpd |
Whether active or not, default simple network management protocol (SNMP) community strings must be changed to maintain security. If the service is running with the default authenticators, then anyone can gather data about the system and the network and use the information to potentially compromise the integrity of the system and network(s). |
| IA-5(c) IA-5(1)(c) CM-6(a) |
Set Password Hashing Algorithm in /etc/login.defs |
In /etc/login.defs, add or update the following line to ensure the system will use
SHA512 as the hashing algorithm:
ENCRYPT_METHOD SHA512 |
Passwords need to be protected at all times, and encryption is the standard method for
protecting passwords. If passwords are not encrypted, they can be plainly read
(i.e., clear text) and easily compromised. Passwords that are encrypted with a weak algorithm
are no more protected than if they are kept in plain text.
Using a stronger hashing algorithm makes password cracking attacks more difficult. |
| IA-5(c) IA-5(1)(a) CM-6(a) IA-5(4) |
Ensure PAM Enforces Password Requirements - Minimum Lowercase Characters | The pam_pwquality module's lcredit parameter controls requirements for usage of lowercase letters in a password. When set to a negative number, any password will be required to contain that many lowercase characters. When set to a positive number, pam_pwquality will grant +1 additional length credit for each lowercase character. Modify the lcredit setting in /etc/security/pwquality.conf to require the use of a lowercase character in passwords. |
Use of a complex password helps to increase the time and resources required
to compromise the password. Password complexity, or strength, is a measure of
the effectiveness of a password in resisting attempts at guessing and brute-force
attacks.
Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possble combinations that need to be tested before the password is compromised. Requiring a minimum number of lowercase characters makes password guessing attacks more difficult by ensuring a larger search space. |
| AU-5(b) AU-5(2) AU-5(1) AU-5(4) CM-6(a) |
Configure auditd Disk Error Action on Disk Error |
The auditd service can be configured to take an action
when there is a disk error.
Edit the file /etc/audit/auditd.conf. Add or modify the following line,
substituting ACTION appropriately:
disk_error_action = ACTIONSet this value to single to cause the system to switch to single-user mode for corrective action. Acceptable values also include syslog, exec, single, and halt. For certain systems, the need for availability outweighs the need to log all actions, and a different setting should be determined. Details regarding all possible values for ACTION are described in the auditd.conf man page. |
Taking appropriate action in case of disk errors will minimize the possibility of losing audit records. |
| IA-5(c) IA-5(1)(b) CM-6(a) IA-5(4) |
Ensure PAM Enforces Password Requirements - Minimum Different Characters |
The pam_pwquality module's difok parameter sets the number of characters
in a password that must not be present in and old password during a password change.
Modify the difok setting in /etc/security/pwquality.conf to equal 8 to require differing characters when changing passwords. |
Use of a complex password helps to increase the time and resources
required to compromise the password. Password complexity, or strength,
is a measure of the effectiveness of a password in resisting attempts
at guessing and brute–force attacks.
Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised. Requiring a minimum number of different characters during password changes ensures that newly changed passwords should not resemble previously compromised ones. Note that passwords which are changed on compromised systems will still be compromised, however. |
| IA-5(h) IA-5(1)(c) CM-6(a) IA-5(7) |
Verify No netrc Files Exist | The .netrc files contain login information used to auto-login into FTP servers and reside in the user's home directory. These files may contain unencrypted passwords to remote FTP servers making them susceptible to access by unauthorized users and should not be used. Any .netrc files should be removed. | Unencrypted passwords for remote FTP servers may be stored in .netrc files. |
| IA-5(c) IA-5(1)(a) CM-6(a) IA-5(4) |
Ensure PAM Enforces Password Requirements - Minimum Different Categories |
The pam_pwquality module's minclass parameter controls
requirements for usage of different character classes, or types, of character
that must exist in a password before it is considered valid. For example,
setting this value to three (3) requires that any password must have characters
from at least three different categories in order to be approved. The default
value is zero (0), meaning there are no required classes. There are four
categories available:
* Upper-case characters * Lower-case characters * Digits * Special characters (for example, punctuation)Modify the minclass setting in /etc/security/pwquality.conf entry to require 3 differing categories of characters when changing passwords. |
Use of a complex password helps to increase the time and resources required to compromise the password.
Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts
at guessing and brute-force attacks.
Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised. Requiring a minimum number of character categories makes password guessing attacks more difficult by ensuring a larger search space. |
| IA-5(f) IA-5(1)(d) CM-6(a) |
Set Password Maximum Age |
To specify password maximum age for new accounts,
edit the file /etc/login.defs
and add or correct the following line:
PASS_MAX_DAYS 60A value of 180 days is sufficient for many environments. The DoD requirement is 60. The profile requirement is 60. |
Any password, no matter how complex, can eventually be cracked. Therefore, passwords
need to be changed periodically. If the operating system does not limit the lifetime
of passwords and force users to change their passwords, there is the risk that the
operating system passwords could be compromised.
Setting the password maximum age ensures users are required to periodically change their passwords. Requiring shorter password lifetimes increases the risk of users writing down the password in a convenient location subject to physical compromise. |
| IA-5(f) IA-5(1)(d) CM-6(a) |
Set Password Minimum Age |
To specify password minimum age for new accounts,
edit the file /etc/login.defs
and add or correct the following line:
PASS_MIN_DAYS 7A value of 1 day is considered sufficient for many environments. The DoD requirement is 1. The profile requirement is 7. |
Enforcing a minimum password lifetime helps to prevent repeated password
changes to defeat the password reuse or history enforcement requirement. If
users are allowed to immediately and continually change their password,
then the password could be repeatedly changed in a short period of time to
defeat the organization's policy regarding password reuse.
Setting the minimum password age protects against users cycling back to a favorite password after satisfying the password reuse requirement. |
| CM-5 CM-5(6) CM-5(6).1 |
Verify that Shared Library Directories Have Restrictive Permissions |
System-wide shared library directories, which contain are linked to executables
during process load time or run time, are stored in the following directories
by default:
/lib /lib64 /usr/lib /usr/lib64Kernel modules, which can be added to the kernel during runtime, are stored in /lib/modules. All sub-directories in these directories should not be group-writable or world-writable. If any file in these directories is found to be group-writable or world-writable, correct its permission with the following command: $ sudo chmod go-w DIR |
If the operating system were to allow any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process. This requirement applies to operating systems with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs which execute with escalated privileges. Only qualified and authorized individuals must be allowed to obtain access to information system components for purposes of initiating changes, including upgrades and modifications. |
| IA-5(f) IA-5(1)(d) CM-6(a) |
Set Existing Passwords Warning Age |
To configure how many days prior to password expiration that a warning will be issued to
users, run the command:
$ sudo chage --warndays 7 USERThe DoD requirement is 7, and CIS recommendation is no less than 7 days. This profile requirement is 7. |
Providing an advance warning that a password will be expiring gives users time to think of a secure password. Users caught unaware may choose a simple password or write it down where it may be discovered. |
| IA-5(c) IA-5(1)(c) CM-6(a) |
Set Password Hashing Algorithm in /etc/libuser.conf |
In /etc/libuser.conf, add or correct the following line in its [defaults]
section to ensure the system will use the sha512
algorithm for password hashing:
crypt_style = sha512 |
Passwords need to be protected at all times, and encryption is the standard method for
protecting passwords. If passwords are not encrypted, they can be plainly read
(i.e., clear text) and easily compromised. Passwords that are encrypted with a weak algorithm
are no more protected than if they are kept in plain text.
This setting ensures user and group account administration utilities are configured to store only encrypted representations of passwords. Additionally, the crypt_style configuration option in /etc/libuser.conf ensures the use of a strong hashing algorithm that makes password cracking attacks more difficult. |
| IA-5(f) IA-5(1)(e) |
Limit Password Reuse: password-auth |
Do not allow users to reuse recent passwords. This can be accomplished by using the
remember option for the pam_pwhistory PAM module.
On systems with newer versions of authselect, the pam_pwhistory PAM module can be enabled via authselect feature: authselect enable-feature with-pwhistoryOtherwise, it should be enabled using an authselect custom profile. Newer systems also have the /etc/security/pwhistory.conf file for setting pam_pwhistory module options. This file should be used whenever available. Otherwise, the pam_pwhistory module options can be set in PAM files. The value for remember option must be equal or greater than 5 |
Preventing re-use of previous passwords helps ensure that a compromised password is not re-used by a user. |
| AU-5(b) AU-5(2) AU-5(1) AU-5(4) CM-6(a) |
Configure auditd space_left on Low Disk Space |
The auditd service can be configured to take an action
when disk space is running low but prior to running out of space completely.
Edit the file /etc/audit/auditd.conf. Add or modify the following line,
substituting SIZE_in_MB appropriately:
space_left = SIZE_in_MBSet this value to the appropriate size in Megabytes cause the system to notify the user of an issue. |
Notifying administrators of an impending disk space problem may allow them to take corrective action prior to any disruption. |
| IA-5(c) IA-5(1)(a) CM-6(a) IA-5(4) |
Ensure PAM Enforces Password Requirements - Minimum Digit Characters | The pam_pwquality module's dcredit parameter controls requirements for usage of digits in a password. When set to a negative number, any password will be required to contain that many digits. When set to a positive number, pam_pwquality will grant +1 additional length credit for each digit. Modify the dcredit setting in /etc/security/pwquality.conf to require the use of a digit in passwords. |
Use of a complex password helps to increase the time and resources required
to compromise the password. Password complexity, or strength, is a measure of
the effectiveness of a password in resisting attempts at guessing and brute-force
attacks.
Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised. Requiring digits makes password guessing attacks more difficult by ensuring a larger search space. |
| AU-5(b) AU-5(2) AU-5(1) AU-5(4) CM-6(a) |
Configure auditd admin_space_left on Low Disk Space |
The auditd service can be configured to take an action
when disk space is running low but prior to running out of space completely.
Edit the file /etc/audit/auditd.conf. Add or modify the following line,
substituting PERCENTAGE appropriately:
admin_space_left = PERCENTAGE%Set this value to 5 to cause the system to perform an action. |
Notifying administrators of an impending disk space problem may allow them to take corrective action prior to any disruption. |
| SC-5 SC-5(1) SC-5(2) SC-5(3)(a) CM-6(a) |
Configure firewalld To Rate Limit Connections |
Create a direct firewall rule to protect against DoS attacks with the following
command:
$ sudo firewall-cmd --permanent --direct --add-rule ipv4 filter INPUT_direct 0 -p tcp -m limit --limit 25/minute --limit-burst 100 -j INPUT_ZONES |
DoS is a condition when a resource is not available for legitimate users. When
this occurs, the organization either cannot accomplish its mission or must
operate at degraded capacity.
This requirement addresses the configuration of the operating system to mitigate the impact of DoS attacks that have occurred or are ongoing on system availability. For each system, known and potential DoS attacks must be identified and solutions for each type implemented. A variety of technologies exist to limit or, in some cases, eliminate the effects of DoS attacks (e.g., limiting processes or establishing memory partitions). Employing increased capacity and bandwidth, combined with service redundancy, may reduce the susceptibility to some DoS attacks. |
| IA-5(h) CM-6(a) |
Verify All Account Password Hashes are Shadowed | If any password hashes are stored in /etc/passwd (in the second field, instead of an x or *), the cause of this misconfiguration should be investigated. The account should have its password reset and the hash should be properly stored, or the account should be deleted entirely. | The hashes for all user account passwords should be stored in the file /etc/shadow and never in /etc/passwd, which is readable by all users. |
| IA-5(f) IA-5(1)(e) |
Limit Password Reuse: system-auth |
Do not allow users to reuse recent passwords. This can be accomplished by using the
remember option for the pam_pwhistory PAM module.
On systems with newer versions of authselect, the pam_pwhistory PAM module can be enabled via authselect feature: authselect enable-feature with-pwhistoryOtherwise, it should be enabled using an authselect custom profile. Newer systems also have the /etc/security/pwhistory.conf file for setting pam_pwhistory module options. This file should be used whenever available. Otherwise, the pam_pwhistory module options can be set in PAM files. The value for remember option must be equal or greater than 5 |
Preventing re-use of previous passwords helps ensure that a compromised password is not re-used by a user. |
| AU-5(b) AU-5(2) AU-5(1) AU-5(4) CM-6(a) |
Configure audispd's Plugin disk_full_action When Disk Is Full |
Configure the action the operating system takes if the disk the audit records
are written to becomes full. Edit the file /etc/audit/audisp-remote.conf.
Add or modify the following line, substituting ACTION appropriately:
disk_full_action = ACTIONSet this value to single to cause the system to switch to single user mode for corrective action. Acceptable values also include syslog and halt. For certain systems, the need for availability outweighs the need to log all actions, and a different setting should be determined. |
Taking appropriate action in case of a filled audit storage volume will minimize the possibility of losing audit records. |
| IA-5(c) IA-5(1)(a) CM-6(a) IA-5(4) |
Ensure PAM Enforces Password Requirements - Maximum Consecutive Repeating Characters from Same Character Class | The pam_pwquality module's maxclassrepeat parameter controls requirements for consecutive repeating characters from the same character class. When set to a positive number, it will reject passwords which contain more than that number of consecutive characters from the same character class. Modify the maxclassrepeat setting in /etc/security/pwquality.conf to equal 4 to prevent a run of (4 + 1) or more identical characters. |
Use of a complex password helps to increase the time and resources required to compromise the password.
Password complexity, or strength, is a measure of the effectiveness of a password in resisting
attempts at guessing and brute-force attacks.
Password complexity is one factor of several that determines how long it takes to crack a password. The more complex a password, the greater the number of possible combinations that need to be tested before the password is compromised. |
| IA-5(f) IA-5(1)(d) CM-6(a) |
Set Existing Passwords Minimum Age |
Configure non-compliant accounts to enforce a 24 hours/1 day minimum password
lifetime by running the following command:
$ sudo chage -m 1 USER |
Enforcing a minimum password lifetime helps to prevent repeated password changes to defeat the password reuse or history enforcement requirement. If users are allowed to immediately and continually change their password, the password could be repeatedly changed in a short period of time to defeat the organization's policy regarding password reuse. |
| IA-5(c) IA-5(1)(a) CM-6(a) IA-5(4) |
Ensure PAM Enforces Password Requirements - Minimum Length | The pam_pwquality module's minlen parameter controls requirements for minimum characters required in a password. Add minlen=15 after pam_pwquality to set minimum password length requirements. |
The shorter the password, the lower the number of possible combinations
that need to be tested before the password is compromised.
Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password length is one factor of several that helps to determine strength and how long it takes to crack a password. Use of more characters in a password helps to exponentially increase the time and/or resources required to compromise the password. |
| IA-5(c) CM-6(a) IA-5(4) |
Set Password Maximum Consecutive Repeating Characters | The pam_pwquality module's maxrepeat parameter controls requirements for consecutive repeating characters. When set to a positive number, it will reject passwords which contain more than that number of consecutive characters. Modify the maxrepeat setting in /etc/security/pwquality.conf to equal 3 to prevent a run of (3 + 1) or more identical characters. |
Use of a complex password helps to increase the time and resources required to compromise the password.
Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at
guessing and brute-force attacks.
Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised. Passwords with excessive repeating characters may be more vulnerable to password-guessing attacks. |
| IA-5(f) IA-5(1)(d) CM-6(a) |
Set Password Warning Age |
To specify how many days prior to password
expiration that a warning will be issued to users,
edit the file /etc/login.defs and add or correct
the following line:
PASS_WARN_AGE 7The DoD requirement is 7. The profile requirement is 7. |
Setting the password warning age enables users to make the change at a practical time. |
| IA-5(c) IA-5(1)(c) CM-6(a) |
Set PAM''s Password Hashing Algorithm |
The PAM system service can be configured to only store encrypted representations of passwords.
In "/etc/pam.d/system-auth", the password section of the file controls which
PAM modules to execute during a password change.
Set the pam_unix.so module in the password section to include the option
sha512 and no other hashing
algorithms as shown below:
password sufficient pam_unix.so sha512 other arguments... This will help ensure that new passwords for local users will be stored using the sha512 algorithm. |
Passwords need to be protected at all times, and encryption is the standard method for
protecting passwords. If passwords are not encrypted, they can be plainly read
(i.e., clear text) and easily compromised. Passwords that are encrypted with a weak algorithm
are no more protected than if they are kept in plain text.
This setting ensures user and group account administration utilities are configured to store only encrypted representations of passwords. Additionally, the crypt_style configuration option in /etc/libuser.conf ensures the use of a strong hashing algorithm that makes password cracking attacks more difficult. |
| AU-5(b) AU-5(2) AU-5(1) AU-5(4) CM-6(a) |
Configure auditd space_left Action on Low Disk Space |
The auditd service can be configured to take an action
when disk space starts to run low.
Edit the file /etc/audit/auditd.conf. Modify the following line,
substituting ACTION appropriately:
space_left_action = ACTIONPossible values for ACTION are described in the auditd.conf man page. These include:
|
Notifying administrators of an impending disk space problem may allow them to take corrective action prior to any disruption. |
| IA-5(c) IA-5(1)(a) CM-6(a) IA-5(4) |
Ensure PAM Enforces Password Requirements - Prevent the Use of Dictionary Words | The pam_pwquality module's dictcheck check if passwords contains dictionary words. When dictcheck is set to 1 passwords will be checked for dictionary words. |
Use of a complex password helps to increase the time and resources required to compromise the password.
Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at
guessing and brute-force attacks.
Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised. Passwords with dictionary words may be more vulnerable to password-guessing attacks. |
| IA-5(c) IA-5(1)(a) CM-6(a) IA-5(4) |
Ensure PAM Enforces Password Requirements - Enforce for root User | The pam_pwquality module's enforce_for_root parameter controls requirements for enforcing password complexity for the root user. Enable the enforce_for_root setting in /etc/security/pwquality.conf to require the root user to use complex passwords. | Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised. |
| IA-5(1) AU-5(a) AU-5(2) CM-6(a) |
Configure auditd mail_acct Action on Low Disk Space |
The auditd service can be configured to send email to
a designated account in certain situations. Add or correct the following line
in /etc/audit/auditd.conf to ensure that administrators are notified
via email for those situations:
action_mail_acct = root |
Email sent to the root account is typically aliased to the administrators of the system, who can take appropriate action. |
| CM-5(1) AU-7(a) AU-7(b) AU-8(b) AU-12(3) AC-6(9) |
Record Events When Privileged Executables Are Run |
Verify the system generates an audit record when privileged functions are executed.
If audit is using the "auditctl" tool to load the rules, run the following command:
$ sudo grep execve /etc/audit/audit.rulesIf audit is using the "augenrules" tool to load the rules, run the following command: $ sudo grep -r execve /etc/audit/rules.d -a always,exit -F arch=b32 -S execve -C uid!=euid -F euid=0 -k setuid -a always,exit -F arch=b64 -S execve -C uid!=euid -F euid=0 -k setuid -a always,exit -F arch=b32 -S execve -C gid!=egid -F egid=0 -k setgid -a always,exit -F arch=b64 -S execve -C gid!=egid -F egid=0 -k setgidIf both the "b32" and "b64" audit rules for "SUID" files are not defined, this is a finding. If both the "b32" and "b64" audit rules for "SGID" files are not defined, this is a finding. |
Misuse of privileged functions, either intentionally or unintentionally by authorized users, or by unauthorized external entities that have compromised information system accounts, is a serious and ongoing concern and can have significant adverse impacts on organizations. Auditing the use of privileged functions is one way to detect such misuse and identify the risk from insider threats and the advanced persistent threat. |
| IA-5(1)(a) IA-5(c) CM-6(a) |
Prevent Login to Accounts With Empty Password | If an account is configured for password authentication but does not have an assigned password, it may be possible to log into the account without authentication. Remove any instances of the nullok in /etc/pam.d/system-auth and /etc/pam.d/password-auth to prevent logins with empty passwords. | If an account has an empty password, anyone could log in and run commands with the privileges of that account. Accounts with empty passwords should never be used in operational environments. |
| IA-5(1)(c) IA-5(1).1(v) IA-7 IA-7.1 |
Verify All Account Password Hashes are Shadowed with SHA512 |
Verify the operating system requires the shadow password suite
configuration be set to encrypt interactive user passwords using a strong
cryptographic hash.
Check that the interactive user account passwords are using a strong
password hash with the following command:
$ sudo cut -d: -f2 /etc/shadow $6$kcOnRq/5$NUEYPuyL.wghQwWssXRcLRFiiru7f5JPV6GaJhNC2aK5F3PZpE/BCCtwrxRc/AInKMNX3CdMw11m9STiql12f/Password hashes ! or * indicate inactive accounts not available for logon and are not evaluated. If any interactive user password hash does not begin with $6, this is a finding. |
Passwords need to be protected at all times, and encryption is the standard method for protecting passwords. If passwords are not encrypted, they can be plainly read (i.e., clear text) and easily compromised. |
| IA-5(1)(a) IA-5(1).1(v) IA-5(1)(a) |
Configure PAMs passwd Module To Implement system-auth Substack When Changing Passwords |
Verify that pam is configured to use /etc/pam.d/system-auth
when changing passwords. Look for the following line in /etc/pam.d/passwd:
password substack system-auth |
Including system-auth from the passwd module ensures that the user must pass through the PAM configuration for system authentication as found in /etc/pam.d/system-auth when changing passwords. |
| IA-5(2) IA-5(2).1 |
OpenSSH Service Must Use Passcode for Their Private Keys |
Verify the SSH private key files have a passcode.
For each private key stored on the system, use the following command:
$ sudo ssh-keygen -y -f /path/to/fileIf the contents of the key are displayed, without asking a passphrase this is a finding. |
If an unauthorized user obtains access to a private key without a passcode, that user would have unauthorized access to any system where the associated public key has been installed. |
| CM-5(3) SI-7 SC-12 SC-12(3) CM-6(a) |
Ensure Amazon GPG Key Installed |
To ensure the system can cryptographically verify base software packages
come from Amazon (and to connect to the Amazon Network to receive them),
the Amazon GPG key must properly be installed. To install the Amazon GPG
key, run:
$ sudo rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-amazon-linux-2023 |
Changes to software components can have significant effects on the overall security of the operating system. This requirement ensures the software has not been tampered with and that it has been provided by a trusted vendor. The Amazon GPG key is necessary to cryptographically verify packages are from Amazon. |
| CM-5(3) SI-7 SC-12 SC-12(3) CM-6(a) |
Ensure SUSE GPG Key Installed |
To ensure the system can cryptographically verify base software packages
come from SUSE (and to connect to the SUSE to receive them),
the SUSE GPG key must properly be installed. To install the SUSE GPG
key, run:
$ sudo zypper install suse-build-keyIf the system is not connected to the Internet or an RHN Satellite, then install the SUSE GPG key from trusted media such as the SUSE installation CD-ROM or DVD. Assuming the disc is mounted in /media/cdrom, use the following command as the root user to import it into the keyring: $ sudo rpm --import /media/cdrom/content.keyor $ sudo rpm --import /media/cdrom/repodata/repomd.xml.keyAlternatively, the key may be pre-loaded during the SUSE installation. In such cases, one can use the repository cache files to install the key, for example by running the following command: sudo rpm --import /var/cache/zypp/raw/Basesystem_Module_15_SP2_x86_64:SLE-Module-Basesystem15-SP2-Pool/repodata/repomd.xml.key |
Changes to software components can have significant effects on the overall security of the operating system. This requirement ensures the software has not been tampered with and that it has been provided by a trusted vendor. The SUSE GPG key is necessary to cryptographically verify packages are from SUSE. |
| CM-5(3) SI-7 SC-12 SC-12(3) CM-6(a) SA-12 SA-12(10) CM-11(a) CM-11(b) |
Ensure gpgcheck Enabled for Repository Metadata | Verify the operating system prevents the installation of patches, service packs, device drivers, or operating system components of local packages without verification of the repository metadata. Check that yum verifies the repository metadata prior to install with the following command. This should be configured by setting repo_gpgcheck to 1 in /etc/yum.conf. | Changes to any software components can have significant effects to the overall security of the operating system. This requirement ensures the software has not been tampered and has been provided by a trusted vendor. Accordingly, patches, service packs, device drivers, or operating system components must be signed with a certificate recognized and approved by the organization. Verifying the authenticity of the software prior to installation validates the integrity of the patch or upgrade received from a vendor. This ensures the software has not been tampered with and that it has been provided by a trusted vendor. Self-signed certificates are disallowed by this requirement. The operating system should not have to verify the software again. NOTE: For U.S. Military systems, this requirement does not mandate DoD certificates for this purpose; however, the certificate used to verify the software must be from an approved Certificate Authority. |
| CM-5(3) SI-7 SC-12 SC-12(3) CM-6(a) CM-11(a) CM-11(b) |
Ensure Oracle Linux GPG Key Installed |
To ensure the system can cryptographically verify base software
packages come from Oracle (and to connect to the Unbreakable Linux Network to
receive them), the Oracle GPG key must properly be installed.
To install the Oracle GPG key, run:
$ sudo uln_registerIf the system is not connected to the Internet, then install the Oracle GPG key from trusted media such as the Oracle installation CD-ROM or DVD. Assuming the disc is mounted in /media/cdrom, use the following command as the root user to import it into the keyring: $ sudo rpm --import /media/cdrom/RPM-GPG-KEY-oracleAlternatively, the key may be pre-loaded during the Oracle installation. In such cases, the key can be installed by running the following command: sudo rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-oracle |
Changes to software components can have significant effects on the overall security of the operating system. This requirement ensures the software has not been tampered with and that it has been provided by a trusted vendor. The Oracle GPG key is necessary to cryptographically verify packages are from Oracle. |
| CM-5(3) SI-7 SC-12 SC-12(3) CM-6(a) |
Ensure Fedora GPG Key Installed |
To ensure the system can cryptographically verify base software
packages come from Fedora (and to connect to the Fedora Network to
receive them), the Fedora GPG key must properly be installed.
To install the Fedora GPG key, run one of the commands below, depending on your Fedora vesion:
$ sudo rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-fedora--primary" $ sudo rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-fedora--primary" |
Changes to software components can have significant effects on the overall security of the operating system. This requirement ensures the software has not been tampered with and that it has been provided by a trusted vendor. The Fedora GPG key is necessary to cryptographically verify packages are from Fedora." |
| CM-5(3) SI-7 SC-12 SC-12(3) CM-6(a) SA-12 SA-12(10) CM-11(a) CM-11(b) |
Ensure gpgcheck Enabled In Main yum Configuration |
The gpgcheck option controls whether
RPM packages' signatures are always checked prior to installation.
To configure yum to check package signatures before installing
them, ensure the following line appears in /etc/yum.conf in
the [main] section:
gpgcheck=1 |
Changes to any software components can have significant effects on the
overall security of the operating system. This requirement ensures the
software has not been tampered with and that it has been provided by a
trusted vendor.
Accordingly, patches, service packs, device drivers, or operating system components must be signed with a certificate recognized and approved by the organization. Verifying the authenticity of the software prior to installation validates the integrity of the patch or upgrade received from a vendor. This ensures the software has not been tampered with and that it has been provided by a trusted vendor. Self-signed certificates are disallowed by this requirement. Certificates used to verify the software must be from an approved Certificate Authority (CA). |
| CM-5(3) SI-7 SC-12 SC-12(3) CM-6(a) SA-12 SA-12(10) CM-11(a) CM-11(b) |
Ensure gpgcheck Enabled for All yum Package Repositories |
To ensure signature checking is not disabled for
any repos, remove any lines from files in /etc/yum.repos.d of the form:
gpgcheck=0 |
Verifying the authenticity of the software prior to installation validates the integrity of the patch or upgrade received from a vendor. This ensures the software has not been tampered with and that it has been provided by a trusted vendor. Self-signed certificates are disallowed by this requirement. Certificates used to verify the software must be from an approved Certificate Authority (CA)." |
| CM-5(3) SI-7 SC-12 SC-12(3) CM-6(a) |
Ensure Red Hat GPG Key Installed |
To ensure the system can cryptographically verify base software packages
come from Red Hat (and to connect to the Red Hat Network to receive them),
the Red Hat GPG key must properly be installed. To install the Red Hat GPG
key, run:
$ sudo subscription-manager registerIf the system is not connected to the Internet or an RHN Satellite, then install the Red Hat GPG key from trusted media such as the Red Hat installation CD-ROM or DVD. Assuming the disc is mounted in /media/cdrom, use the following command as the root user to import it into the keyring: $ sudo rpm --import /media/cdrom/RPM-GPG-KEYAlternatively, the key may be pre-loaded during the RHEL installation. In such cases, the key can be installed by running the following command: sudo rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release |
Changes to software components can have significant effects on the overall security of the operating system. This requirement ensures the software has not been tampered with and that it has been provided by a trusted vendor. The Red Hat GPG key is necessary to cryptographically verify packages are from Red Hat. |
| CM-5(6) CM-5(6).1 |
Verify that system commands files are group owned by root or a system account |
System commands files are stored in the following directories by default:
/bin /sbin /usr/bin /usr/sbin /usr/local/bin /usr/local/sbinAll files in these directories should be owned by the root group, or a system account. If the directory, or any file in these directories, is found to be owned by a group other than root or a a system account correct its ownership with the following command: $ sudo chgrp root FILE |
If the operating system allows any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process. This requirement applies to operating systems with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs which execute with escalated privileges. Only qualified and authorized individuals must be allowed to obtain access to information system components for purposes of initiating changes, including upgrades and modifications. |
| CM-5(6) CM-5(6).1 |
Verify that system commands directories have root ownership |
System commands are stored in the following directories by default:
/bin /sbin /usr/bin /usr/sbin /usr/local/bin /usr/local/sbinAll these directories should be owned by the root user. If any system command directory is not owned by a user other than root correct its ownership with the following command: $ sudo chown root DIR |
If the operating system were to allow any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process. This requirement applies to operating systems with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs which execute with escalated privileges. Only qualified and authorized individuals must be allowed to obtain access to information system components for purposes of initiating changes, including upgrades and modifications. |
| CM-5(6) CM-5(6).1 |
Verify that Shared Library Directories Have Root Ownership |
System-wide shared library files, which are linked to executables
during process load time or run time, are stored in the following directories
by default:
/lib /lib64 /usr/lib /usr/lib64Kernel modules, which can be added to the kernel during runtime, are also stored in /lib/modules. All files in these directories should be owned by the root user. If the directories, is found to be owned by a user other than root correct its ownership with the following command: $ sudo chown root DIR |
Files from shared library directories are loaded into the address space of processes (including privileged ones) or of the kernel itself at runtime. Proper ownership of library directories is necessary to protect the integrity of the system. |
| CM-5(6) CM-5(6).1 |
Verify that Shared Library Directories Have Root Group Ownership |
System-wide shared library files, which are linked to executables
during process load time or run time, are stored in the following directories
by default:
/lib /lib64 /usr/lib /usr/lib64Kernel modules, which can be added to the kernel during runtime, are also stored in /lib/modules. All files in these directories should be group-owned by the root user. If the directories, is found to be owned by a user other than root correct its ownership with the following command: $ sudo chgrp root DIR |
Files from shared library directories are loaded into the address space of processes (including privileged ones) or of the kernel itself at runtime. Proper ownership of library directories is necessary to protect the integrity of the system. |
| CM-5(6) CM-5(6).1 |
Verify that system commands directories have root as a group owner |
System commands are stored in the following directories:
by default:
/bin /sbin /usr/bin /usr/sbin /usr/local/bin /usr/local/sbinAll these directories should have root user as a group owner. If any system command directory is not group owned by a user other than root correct its ownership with the following command: $ sudo chgrp root DIR |
If the operating system were to allow any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process. This requirement applies to operating systems with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs which execute with escalated privileges. Only qualified and authorized individuals must be allowed to obtain access to information system components for purposes of initiating changes, including upgrades and modifications. |
| CM-5(6) CM-5(6).1 CM-6(a) AC-6(1) |
Verify that System Executables Have Root Ownership |
System executables are stored in the following directories by default:
/bin /sbin /usr/bin /usr/libexec /usr/local/bin /usr/local/sbin /usr/sbinAll files in these directories should be owned by the root user. If any file FILE in these directories is found to be owned by a user other than root, correct its ownership with the following command: $ sudo chown root FILE |
System binaries are executed by privileged users as well as system services, and restrictive permissions are necessary to ensure that their execution of these programs cannot be co-opted. |
| CM-5(6) CM-5(6).1 |
Verify the system-wide library files in directories "/lib", "/lib64", "/usr/lib/" and "/usr/lib64" are group-owned by root. |
System-wide library files are stored in the following directories
by default:
/lib /lib64 /usr/lib /usr/lib64All system-wide shared library files should be protected from unauthorised access. If any of these files is not group-owned by root, correct its group-owner with the following command: $ sudo chgrp root FILE |
If the operating system were to allow any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process. This requirement applies to operating systems with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs which execute with escalated privileges. Only qualified and authorized individuals must be allowed to obtain access to information system components for purposes of initiating changes, including upgrades and modifications. |
| CM-5(6) CM-5(6).1 CM-6(a) AC-6(1) |
Verify that Shared Library Files Have Root Ownership |
System-wide shared library files, which are linked to executables
during process load time or run time, are stored in the following directories
by default:
/lib /lib64 /usr/lib /usr/lib64Kernel modules, which can be added to the kernel during runtime, are also stored in /lib/modules. All files in these directories should be owned by the root user. If the directory, or any file in these directories, is found to be owned by a user other than root correct its ownership with the following command: $ sudo chown root FILE |
Files from shared library directories are loaded into the address space of processes (including privileged ones) or of the kernel itself at runtime. Proper ownership is necessary to protect the integrity of the system. |
| CM-5(6) CM-5(6).1 CM-6(a) AC-6(1) |
Verify that System Executables Have Restrictive Permissions |
System executables are stored in the following directories by default:
/bin /sbin /usr/bin /usr/libexec /usr/local/bin /usr/local/sbin /usr/sbinAll files in these directories should not be group-writable or world-writable. If any file FILE in these directories is found to be group-writable or world-writable, correct its permission with the following command: $ sudo chmod go-w FILE |
System binaries are executed by privileged users, as well as system services, and restrictive permissions are necessary to ensure execution of these programs cannot be co-opted. |
| CM-5(6) CM-5(6).1 |
Verify that system commands are protected from unauthorized access |
System commands are stored in the following directories by default:
/bin /sbin /usr/bin /usr/sbin /usr/local/bin /usr/local/sbinAll files in these directories should not be group-writable or world-writable. If any file FILE in these directories is found to be group-writable or world-writable, correct its permission with the following command: $ sudo chmod 755 FILE |
System binaries are executed by privileged users, as well as system services, and restrictive permissions are necessary to ensure execution of these programs cannot be co-opted. |
| CM-6(a) AC-6(1) |
Verify User Who Owns group File |
To properly set the owner of /etc/group, run the command: $ sudo chown root /etc/group |
The /etc/group file contains information regarding groups that are configured on the system. Protection of this file is important for system security. |
| AC-6 (1) | Verify Group Who Owns Backup passwd File |
To properly set the group owner of /etc/passwd-, run the command: $ sudo chgrp root /etc/passwd- |
The /etc/passwd- file is a backup file of /etc/passwd, and as such, it contains information about the users that are configured on the system. Protection of this file is critical for system security. |
| CM-6(a) | Enable SLUB/SLAB allocator poisoning |
To enable poisoning of SLUB/SLAB objects,
add the argument slub_debug=P to the default
GRUB 2 command line for the Linux operating system.
To ensure that slub_debug=P is added as a kernel command line
argument to newly installed kernels, add slub_debug=P to the
default Grub2 command line for Linux operating systems. Modify the line within
/etc/default/grub as shown below:
GRUB_CMDLINE_LINUX="... slub_debug=P ..."Run the following command to update command line for already installed kernels: # grubby --update-kernel=ALL --args="slub_debug=P" |
Poisoning writes an arbitrary value to freed objects, so any modification or reference to that object after being freed or before being initialized will be detected and prevented. This prevents many types of use-after-free vulnerabilities at little performance cost. Also prevents leak of data and detection of corrupted memory. |
| CM-6(a) AC-6(1) AU-9(4) |
System Audit Logs Must Be Owned By Root |
All audit logs must be owned by root user. The path for audit log can be
configured via log_file parameter in /etc/audit/auditd.confor by default, the path for audit log is /var/log/audit/. To properly set the owner of /var/log/audit/*, run the command:
$ sudo chown root /var/log/audit/* |
Unauthorized disclosure of audit records can reveal system and configuration data to attackers, thus compromising its confidentiality. |
| CM-6(a) AU-8(1)(a) |
Enable the NTP Daemon |
The ntpd service can be enabled with the following command:
$ sudo systemctl enable ntpd.service |
Enabling the ntpd service ensures that the ntpd
service will be running and that the system will synchronize its time to
any servers specified. This is important whether the system is configured to be
a client (and synchronize only its own clock) or it is also acting as an NTP
server to other systems. Synchronizing time is essential for authentication
services such as Kerberos, but it is also important for maintaining accurate
logs and auditing possible security breaches.
The NTP daemon offers all of the functionality of ntpdate, which is now deprecated. |
| CM-6(a) | Configure System to Forward All Mail For The Root Account |
Make sure that mails delivered to root user are forwarded to a monitored
email address. Make sure that the address
change_me@localhost is a valid email address
reachable from the system in question. Use the following command to
configure the alias:
$ sudo echo "root: change_me@localhost" >> /etc/aliases $ sudo newaliases |
A number of system services utilize email messages sent to the root user to notify system administrators of active or impending issues. These messages must be forwarded to at least one monitored email address. |
| CM-6(a) AU-6(3) AU-6(4) |
Enable rsyslog to Accept Messages via UDP, if Acting As Log Server |
The rsyslog daemon should not accept remote messages
unless the system acts as a log server.
If the system needs to act as a central log server, add the following lines to
/etc/rsyslog.conf to enable reception of messages over UDP:
$ModLoad imudp $UDPServerRun 514 |
Many devices, such as switches, routers, and other Unix-like systems, may only support the traditional syslog transmission over UDP. If the system must act as a log server, this enables it to receive their messages as well. |
| CM-6(a) | Serve Avahi Only via Required Protocol |
If you are using only IPv4, edit /etc/avahi/avahi-daemon.conf and ensure
the following line exists in the [server] section:
use-ipv6=noSimilarly, if you are using only IPv6, disable IPv4 sockets with the line: use-ipv4=no |
|
| CM-6(a) | Ensure syslog-ng is Installed |
syslog-ng can be installed in replacement of rsyslog.
The syslog-ng-core package can be installed with the following command:
$ sudo yum install syslog-ng-core |
The syslog-ng-core package provides the syslog-ng daemon, which provides system logging services. |
| CM-6(a) AC-6(1) |
Enable Kernel Parameter to Enforce DAC on Regular files |
To set the runtime status of the fs.protected_regular kernel parameter, run the following command: $ sudo sysctl -w fs.protected_regular=2To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: fs.protected_regular = 2 |
This parameter is available since Linux Kernel 4.19 and allows to prohibit opening "regular" files that are not owned by the user in world and group writeable sticky directories. It avoids writes to an attacker-controlled regular file, for example, when a program expects to create the regular file. |
| CM-6(a) AC-6(1) |
Verify Permissions on cron.weekly |
To properly set the permissions of /etc/cron.weekly, run the command:
$ sudo chmod 0700 /etc/cron.weekly |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should have the correct access rights to prevent unauthorized changes. |
| CM-6(b) | Disable X11 Forwarding |
The X11Forwarding parameter provides the ability to tunnel X11 traffic
through the connection to enable remote graphic connections.
SSH has the capability to encrypt remote X11 connections when SSH's
X11Forwarding option is enabled.
The default SSH configuration disables X11Forwarding. The appropriate configuration is used if no value is set for X11Forwarding. To explicitly disable X11 Forwarding, add or correct the following line in /etc/ssh/sshd_config: X11Forwarding no |
Disable X11 forwarding unless there is an operational requirement to use X11 applications directly. There is a small risk that the remote X11 servers of users who are logged in via SSH with X11 forwarding could be compromised by other users on the X11 server. Note that even if X11 forwarding is disabled, users can always install their own forwarders. |
| CM-6(a) AC-6(1) |
Verify User Who Owns passwd File |
To properly set the owner of /etc/passwd, run the command: $ sudo chown root /etc/passwd |
The /etc/passwd file contains information about the users that are configured on the system. Protection of this file is critical for system security. |
| CM-6(a) AU-4(1) |
Enable syslog-ng Service |
The syslog-ng service (in replacement of rsyslog) provides syslog-style logging by default on Debian.
The syslog-ng service can be enabled with the following command:
$ sudo systemctl enable syslog-ng.service |
The syslog-ng service must be running in order to provide logging services, which are essential to system administration. |
| CM-6(a) AC-17(a) AC-17(2) |
Require Encryption for Remote Access in GNOME3 |
By default, GNOME requires encryption when using Vino for remote access.
To prevent remote access encryption from being disabled, add or set
require-encryption to true in
/etc/dconf/db/local.d/00-security-settings. For example:
[org/gnome/Vino] require-encryption=trueOnce the settings have been added, add a lock to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification. For example: /org/gnome/Vino/require-encryptionAfter the settings have been set, run dconf update. |
Open X displays allow an attacker to capture keystrokes and to execute commands remotely. |
| CM-6(a) AU-6(3) AU-6(4) |
Enable rsyslog to Accept Messages via TCP, if Acting As Log Server |
The rsyslog daemon should not accept remote messages
unless the system acts as a log server.
If the system needs to act as a central log server, add the following lines to
/etc/rsyslog.conf to enable reception of messages over TCP:
$ModLoad imtcp $InputTCPServerRun 514 |
If the system needs to act as a log server, this ensures that it can receive messages over a reliable TCP connection. |
| CM-6(a) | Check Avahi Responses' TTL Field |
To make Avahi ignore packets unless the TTL field is 255, edit
/etc/avahi/avahi-daemon.conf and ensure the following line
appears in the [server] section:
check-response-ttl=yes |
This helps to ensure that only mDNS responses from the local network are processed, because the TTL field in a packet is decremented from its initial value of 255 whenever it is routed from one network to another. Although a properly-configured router or firewall should not allow mDNS packets into the local network at all, this option provides another check to ensure they are not permitted. |
| CM-6(a) AC-6(1) |
Verify /boot/grub2/user.cfg Permissions |
File permissions for /boot/grub2/user.cfg should be set to 600.
To properly set the permissions of /boot/grub2/user.cfg, run the command:
$ sudo chmod 600 /boot/grub2/user.cfg |
Proper permissions ensure that only the root user can read or modify important boot parameters. |
| CM-6(b) | Disable graphical user interface |
By removing the following packages, the system no longer has X Windows installed.
xorg-x11-server-Xorg xorg-x11-server-common xorg-x11-server-utils xorg-x11-server-Xwayland
If X Windows is not installed then the system cannot boot into graphical user mode.
This prevents the system from being accidentally or maliciously booted into a graphical.target
mode. To do so, run the following command:
sudo yum remove xorg-x11-server-Xorg xorg-x11-server-common xorg-x11-server-utils xorg-x11-server-Xwayland |
Unnecessary service packages must not be installed to decrease the attack surface of the system. X windows has a long history of security vulnerabilities and should not be installed unless approved and documented. |
| CM-6(a) AU-8(1)(a) |
A remote time server for Chrony is configured |
Chrony is a daemon which implements the Network Time Protocol (NTP). It is designed
to synchronize system clocks across a variety of systems and use a source that is highly
accurate. More information on chrony can be found at
https://chrony-project.org/.
Chrony can be configured to be a client and/or a server.
Add or edit server or pool lines to /etc/chrony.conf as appropriate:
server <remote-server>Multiple servers may be configured. |
If chrony is in use on the system proper configuration is vital to ensuring time synchronization is working properly. |
| CM-6(b) CM-6.1(iv) |
Disable Kernel Parameter for IPv6 Forwarding by default |
To set the runtime status of the net.ipv6.conf.default.forwarding kernel parameter, run the following command: $ sudo sysctl -w net.ipv6.conf.default.forwarding=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv6.conf.default.forwarding = 0 |
IP forwarding permits the kernel to forward packets from one network interface to another. The ability to forward packets between two networks is only appropriate for systems acting as routers. |
| CM-6(a) | Extend Audit Backlog Limit for the Audit Daemon |
To improve the kernel capacity to queue all log events, even those which occurred
prior to the audit daemon, add the argument audit_backlog_limit=8192 to the default
GRUB 2 command line for the Linux operating system.
To ensure that audit_backlog_limit=8192 is added as a kernel command line
argument to newly installed kernels, add audit_backlog_limit=8192 to the
default Grub2 command line for Linux operating systems. Modify the line within
/etc/default/grub as shown below:
GRUB_CMDLINE_LINUX="... audit_backlog_limit=8192 ..."Run the following command to update command line for already installed kernels: # grubby --update-kernel=ALL --args="audit_backlog_limit=8192" |
audit_backlog_limit sets the queue length for audit events awaiting transfer to the audit daemon. Until the audit daemon is up and running, all log messages are stored in this queue. If the queue is overrun during boot process, the action defined by audit failure flag is taken. |
| CM-6(a) AC-17(a) AC-2(5) AC-12 AC-17(a) SC-10 CM-6(a) |
Set SSH Client Alive Interval |
SSH allows administrators to set a network responsiveness timeout interval.
After this interval has passed, the unresponsive client will be automatically logged out.
To set this timeout interval, edit the following line in /etc/ssh/sshd_config as follows: ClientAliveInterval 300 The timeout interval is given in seconds. For example, have a timeout of 10 minutes, set interval to 600. If a shorter timeout has already been set for the login shell, that value will preempt any SSH setting made in /etc/ssh/sshd_config. Keep in mind that some processes may stop SSH from correctly detecting that the user is idle. |
Terminating an idle ssh session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been let unattended. |
| CM-6(a) | Install vsftpd Package |
If this system must operate as an FTP server, install the vsftpd package via the standard channels.
The vsftpd package can be installed with the following command:
$ sudo yum install vsftpd |
After Red Hat Enterprise Linux 2.1, Red Hat switched from distributing wu-ftpd with Red Hat Enterprise Linux to distributing vsftpd. For security and for consistency with future Red Hat releases, the use of vsftpd is recommended. |
| CM-6(a) | Ensure rsyslog is Installed |
Rsyslog is installed by default. The rsyslog package can be installed with the following command: $ sudo yum install rsyslog |
The rsyslog package provides the rsyslog daemon, which provides system logging services. |
| CM-6(a) | Install the OpenSSH Client and Server Package |
The openssh package should be installed.
The openssh package can be installed with the following command:
$ sudo yum install openssh |
Without protection of the transmitted information, confidentiality, and integrity may be compromised because unprotected communications can be intercepted and either read or altered. |
| CM-6(a) | Install the Host Intrusion Prevention System (HIPS) Module | Install the McAfee Host Intrusion Prevention System (HIPS) Module if it is absolutely necessary. If SELinux is enabled, do not install or enable this module. | Without a host-based intrusion detection tool, there is no system-level defense when an intruder gains access to a system or network. Additionally, a host-based intrusion prevention tool can provide methods to immediately lock out detected intrusion attempts. |
| CM-6(a) SC-8 SC-8(1) SC-8(2) SC-8(3) SC-8(4) |
Enable the OpenSSH Service |
The SSH server service, sshd, is commonly needed.
The sshd service can be enabled with the following command:
$ sudo systemctl enable sshd.service |
Without protection of the transmitted information, confidentiality, and
integrity may be compromised because unprotected communications can be
intercepted and either read or altered.
This checklist item applies to both internal and external networks and all types of information system components from which information can be transmitted (e.g., servers, mobile devices, notebook computers, printers, copiers, scanners, etc). Communication paths outside the physical protection of a controlled boundary are exposed to the possibility of interception and modification. |
| CM-6(a) AC-6(1) |
Ensure System Log Files Have Correct Permissions |
The file permissions for all log files written by rsyslog should
be set to 640, or more restrictive. These log files are determined by the
second part of each Rule line in /etc/rsyslog.conf and typically
all appear in /var/log. For each log file LOGFILE
referenced in /etc/rsyslog.conf, run the following command to
inspect the file's permissions:
$ ls -l LOGFILEIf the permissions are not 640 or more restrictive, run the following command to correct this: $ sudo chmod 640 LOGFILE" |
Log files can contain valuable information regarding system configuration. If the system log files are not protected unauthorized users could change the logged data, eliminating their forensic value. |
| CM-6(a) AC-6(1) |
Verify Owner on cron.monthly |
To properly set the owner of /etc/cron.monthly, run the command:
$ sudo chown root /etc/cron.monthly |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct user to prevent unauthorized changes. |
| CM-6(a) AC-6(1) |
Verify Owner on cron.hourly |
To properly set the owner of /etc/cron.hourly, run the command:
$ sudo chown root /etc/cron.hourly |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct user to prevent unauthorized changes. |
| CM-6(a) | Ensure Logrotate Runs Periodically |
The logrotate utility allows for the automatic rotation of
log files. The frequency of rotation is specified in /etc/logrotate.conf,
which triggers a cron task or a timer. To configure logrotate to run daily, add or correct
the following line in /etc/logrotate.conf:
# rotate log files frequency daily |
Log files that are not properly rotated run the risk of growing so large that they fill up the /var/log partition. Valuable logging information could be lost if the /var/log partition becomes full. |
| CM-6 b | Verify Owner on cron.deny |
To properly set the owner of /etc/cron.deny, run the command:
$ sudo chown root /etc/cron.deny |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct user to prevent unauthorized changes. |
| CM-6(a) SC-28 SI-3(a) SI-3(b) SI-3(2) |
Virus Scanning Software Definitions Are Updated | Ensure virus definition files are no older than 7 days or their last release. | Virus scanning software can be used to detect if a system has been compromised by computer viruses, as well as to limit their spread to other systems. |
| CM-6(a) | Install iptables-nft Package |
The iptables-nft package can be installed with the following command:
$ sudo yum install iptables-nft |
iptables-nft controls the Linux kernel network packet filtering code. iptables-nft allows system operators to set up firewalls and IP masquerading, etc. |
| CM-6(a) | Install Intrusion Detection Software | The base Red Hat Enterprise Linux 8 platform already includes a sophisticated auditing system that can detect intruder activity, as well as SELinux, which provides host-based intrusion prevention capabilities by confining privileged programs and user sessions which may become compromised. | Host-based intrusion detection tools provide a system-level defense when an intruder gains access to a system or network. |
| CM-6(a) SI-4(22) |
Enable the File Access Policy Service |
The File Access Policy service should be enabled.
The fapolicyd service can be enabled with the following command:
$ sudo systemctl enable fapolicyd.service |
The fapolicyd service (File Access Policy Daemon) implements application whitelisting to decide file access rights. |
| CM-6(a) SC-5(2) |
Ensure /tmp Located On Separate Partition | The /tmp directory is a world-writable directory used for temporary file storage. Ensure it has its own partition or logical volume at installation time, or migrate it using LVM. | The /tmp partition is used as temporary storage by many programs. Placing /tmp in its own partition enables the setting of more restrictive mount options, which can help protect programs which use it. |
| CM-6(a) AC-6(1) |
Verify Permissions on cron.daily |
To properly set the permissions of /etc/cron.daily, run the command:
$ sudo chmod 0700 /etc/cron.daily |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should have the correct access rights to prevent unauthorized changes. |
| CM-6(a) AC-6(1) AU-9(4) |
System Audit Directories Must Be Group Owned By Root |
All audit directories must be group owned by root user. By default, the path for audit log is /var/log/audit/. To properly set the group owner of /var/log/audit, run the command:
$ sudo chgrp root /var/log/auditIf log_group in /etc/audit/auditd.conf is set to a group other than the root group account, change the group ownership of the audit directories to this specific group. |
Unauthorized disclosure of audit records can reveal system and configuration data to attackers, thus compromising its confidentiality. |
| CM-6(a) AC-23 |
Disable the GNOME3 Login User List |
In the default graphical environment, users logging directly into the
system are greeted with a login screen that displays all known users.
This functionality should be disabled by setting disable-user-list
to true.
To disable, add or edit disable-user-list to /etc/dconf/db/gdm.d/00-security-settings. For example: [org/gnome/login-screen] disable-user-list=trueOnce the setting has been added, add a lock to /etc/dconf/db/gdm.d/locks/00-security-settings-lock to prevent user modification. For example: /org/gnome/login-screen/disable-user-listAfter the settings have been set, run dconf update. |
Leaving the user list enabled is a security risk since it allows anyone with physical access to the system to quickly enumerate known user accounts without logging in. |
| CM-6(a) | Install the ntp service | The ntpd service should be installed. | Time synchronization (using NTP) is required by almost all network and administrative tasks (syslog, cryptographic based services (authentication, etc.), etc.). Ntpd is regulary maintained and updated, supporting security features such as RFC 5906. |
| CM-6(a) AC-17(a) AC-17(2) SC-13 MA-4(6) SC-12(2) SC-12(3) |
Use Only FIPS 140-2 Validated MACs |
Limit the MACs to those hash algorithms which are FIPS-approved.
The following line in /etc/ssh/sshd_config
demonstrates use of FIPS-approved MACs:
MACs hmac-sha2-512,hmac-sha2-256,hmac-sha1The man page sshd_config(5) contains a list of supported MACs. The rule is parametrized to use the following MACs: hmac-sha2-512,hmac-sha2-256,hmac-sha1,hmac-sha1-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com.
|
DoD Information Systems are required to use FIPS-approved cryptographic hash functions. The only SSHv2 hash algorithms meeting this requirement is SHA2. |
| CM-6(d) CM-6(c) SI-7 SI-7(1) SI-7(6) AU-9(3) CM-6(a) |
Verify and Correct File Permissions with RPM |
The RPM package management system can check file access permissions of installed software
packages, including many that are important to system security. Verify that the file
permissions of system files and commands match vendor values. Check the file permissions with
the following command:
$ sudo rpm -Va | awk '{ if (substr($0,2,1)=="M") print $NF }'
Output indicates files that do not match vendor defaults.
After locating a file with incorrect permissions, run the following command to determine which
package owns it:
$ rpm -qf FILENAME Next, run the following command to reset its permissions to the correct values: $ sudo rpm --restore PACKAGENAME |
Permissions on system binaries and configuration files that are too generous could allow an unauthorized user to gain privileges that they should not have. The permissions set by the vendor should be maintained. Any deviations from this baseline should be investigated. |
| AC-6 (1) | Verify Permissions on Backup passwd File |
To properly set the permissions of /etc/passwd-, run the command:
$ sudo chmod 0644 /etc/passwd- |
The /etc/passwd- file is a backup file of /etc/passwd, and as such, it contains information about the users that are configured on the system. Protection of this file is critical for system security. |
| CM-6(a) AU-8(1)(a) AU-8(2) AU-12(1) |
Specify a Remote NTP Server |
Depending on specific functional requirements of a concrete
production environment, the Red Hat Enterprise Linux 8 system can be
configured to utilize the services of the chronyd NTP daemon (the
default), or services of the ntpd NTP daemon. Refer to
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/system_administrators_guide/ch-configuring_ntp_using_the_chrony_suite
for more detailed comparison of the features of both of the choices, and for
further guidance how to choose between the two NTP daemons.
To specify a remote NTP server for time synchronization, perform the following:
server ntpserverThis instructs the NTP software to contact that remote server to obtain time data. |
Synchronizing with an NTP server makes it possible to collate system logs from multiple sources or correlate computer events with real time events. |
| CM-6(a) AC-6(1) |
Verify Permissions on cron.d |
To properly set the permissions of /etc/cron.d, run the command:
$ sudo chmod 0700 /etc/cron.d |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should have the correct access rights to prevent unauthorized changes. |
| CM-6(a) AC-6(1) CM-6(a) |
Disable Ctrl-Alt-Del Burst Action |
By default, SystemD will reboot the system if the Ctrl-Alt-Del
key sequence is pressed Ctrl-Alt-Delete more than 7 times in 2 seconds.
To configure the system to ignore the CtrlAltDelBurstAction setting, add or modify the following to /etc/systemd/system.conf: CtrlAltDelBurstAction=none |
A locally logged-in user who presses Ctrl-Alt-Del, when at the console, can reboot the system. If accidentally pressed, as could happen in the case of mixed OS environment, this can create the risk of short-term loss of availability of systems due to unintentional reboot. |
| CM-6(b) CM-6.1(iv) |
Disable GDM Unattended or Automatic Login |
The GNOME Display Manager (GDM) can allow users to automatically login without
user interaction or credentials or unattended login. User should always be required to authenticate themselves
to the system that they are authorized to use. To disable user ability to automatically
login to the system, set the DISPLAYMANAGER_AUTOLOGIN=""
or DISPLAYMANAGER_PASSWORD_LESS_LOGIN="no" in the
/etc/sysconfig/displaymanager. For example:
DISPLAYMANAGER_AUTOLOGIN="" DISPLAYMANAGER_PASSWORD_LESS_LOGIN="no" |
Failure to restrict system access to authenticated users negatively impacts operating system security. |
| CM-6(a) MP-2 |
Mount Remote Filesystems with nodev |
Add the nodev option to the fourth column of /etc/fstab for the line which controls mounting of
any NFS mounts.
|
Legitimate device files should only exist in the /dev directory. NFS mounts should not present device files to users. |
| CM-6(b) | Add usrquota Option to /home |
The usrquota mount option allows for the filesystem to have disk quotas configured.
Add the usrquota option to the fourth column of
/etc/fstab for the line which controls mounting of
/home.
|
To ensure the availability of disk space on /home, it is important to limit the impact a single user or group can cause for other users (or the wider system) by intentionally or accidentally filling up the partition. Quotas can also be applied to inodes for filesystems where inode exhaustion is a concern. |
| CM-6(a) | Install the SSSD Package |
The sssd package should be installed.
The sssd package can be installed with the following command:
$ sudo yum install sssd |
|
| CM-6(a) | Install the Asset Configuration Compliance Module (ACCM) | Install the Asset Configuration Compliance Module (ACCM). | Without a host-based intrusion detection tool, there is no system-level defense when an intruder gains access to a system or network. Additionally, a host-based intrusion prevention tool can provide methods to immediately lock out detected intrusion attempts. |
| CM-6(a) AC-7(b) IA-5(c) |
Configure the root Account for Failed Password Attempts | This rule configures the system to lock out the root account after a number of incorrect login attempts using pam_faillock.so. pam_faillock.so module requires multiple entries in pam files. These entries must be carefully defined to work as expected. In order to avoid errors when manually editing these files, it is recommended to use the appropriate tools, such as authselect or authconfig, depending on the OS version. | By limiting the number of failed logon attempts, the risk of unauthorized system access via user password guessing, also known as brute-forcing, is reduced. Limits are imposed by locking the account. |
| CM-6(b) | Disable Kernel Parameter for IPv4 Forwarding on all IPv4 Interfaces |
To set the runtime status of the net.ipv4.conf.all.forwarding kernel parameter, run the following command: $ sudo sysctl -w net.ipv4.conf.all.forwarding=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv4.conf.all.forwarding = 0 |
IP forwarding permits the kernel to forward packets from one network interface to another. The ability to forward packets between two networks is only appropriate for systems acting as routers. |
| AC-6 AC-17(a) CM-6(a) |
Enable Use of Strict Mode Checking |
SSHs StrictModes option checks file and ownership permissions in
the user's home directory .ssh folder before accepting login. If world-
writable permissions are found, logon is rejected.
The default SSH configuration has StrictModes enabled. The appropriate configuration is used if no value is set for StrictModes. To explicitly enable StrictModes in SSH, add or correct the following line in /etc/ssh/sshd_config: StrictModes yes |
If other users have access to modify user-specific SSH configuration files, they may be able to log into the system as another user. |
| CM-6(a) AC-6(1) |
Verify User Who Owns shadow File |
To properly set the owner of /etc/shadow, run the command: $ sudo chown root /etc/shadow |
The /etc/shadow file contains the list of local system accounts and stores password hashes. Protection of this file is critical for system security. Failure to give ownership of this file to root provides the designated owner with access to sensitive information which could weaken the system security posture. |
| AC-6 (1) | Verify Permissions on Backup group File |
To properly set the permissions of /etc/group-, run the command:
$ sudo chmod 0644 /etc/group- |
The /etc/group- file is a backup file of /etc/group, and as such, it contains information regarding groups that are configured on the system. Protection of this file is important for system security. |
| CM-6(a) AC-7(b) IA-5(c) |
Set Lockout Time for Failed Password Attempts using pam_tally2 | This rule configures the system to lock out accounts during a specified time period after a number of incorrect login attempts using pam_tally2.so. | By limiting the number of failed logon attempts, the risk of unauthorized system access via user password guessing, also known as brute-forcing, is reduced. Limits are imposed by locking the account. |
| CM-6(a) AC-6(1) |
Verify Owner on cron.d |
To properly set the owner of /etc/cron.d, run the command:
$ sudo chown root /etc/cron.d |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct user to prevent unauthorized changes. |
| CM-6(a) | Install iptables Package |
The iptables package can be installed with the following command:
$ sudo yum install iptables |
iptables controls the Linux kernel network packet filtering code. iptables allows system operators to set up firewalls and IP masquerading, etc. |
| CM-6(a) AC-6(1) |
Verify /boot/grub2/user.cfg Group Ownership |
The file /boot/grub2/user.cfg should be group-owned by the root
group to prevent reading or modification of the file.
To properly set the group owner of /boot/grub2/user.cfg, run the command:
$ sudo chgrp root /boot/grub2/user.cfg |
The root group is a highly-privileged group. Furthermore, the group-owner of this file should not have any access privileges anyway. Non-root users who read the boot parameters may be able to identify weaknesses in security upon boot and be able to exploit them. |
| CM-6(a) AC-6(1) CM-7(b) |
Disable GDM Automatic Login |
The GNOME Display Manager (GDM) can allow users to automatically login without
user interaction or credentials. User should always be required to authenticate themselves
to the system that they are authorized to use. To disable user ability to automatically
login to the system, set the AutomaticLoginEnable to false in the
[daemon] section in /etc/gdm/custom.conf. For example:
[daemon] AutomaticLoginEnable=false |
Failure to restrict system access to authenticated users negatively impacts operating system security. |
| AC-6 (1) | Verify User Who Owns Backup passwd File |
To properly set the owner of /etc/passwd-, run the command: $ sudo chown root /etc/passwd- |
The /etc/passwd- file is a backup file of /etc/passwd, and as such, it contains information about the users that are configured on the system. Protection of this file is critical for system security. |
| CM-6(a) AC-6(1) |
Ensure All Files Are Owned by a User |
If any files are not owned by a user, then the cause of their lack of ownership should be
investigated. Following this, the files should be deleted or assigned to an appropriate user.
Locate the mount points related to local devices by the following command:
$ findmnt -n -l -k -it $(awk '/nodev/ { print $2 }' /proc/filesystems | paste -sd,)
For all mount points listed by the previous command, it is necessary to search for files which
do not belong to a valid user using the following command:
$ sudo find MOUNTPOINT -xdev -nouser 2>/dev/null |
Unowned files do not directly imply a security problem, but they are generally a sign that something is amiss. They may be caused by an intruder, by incorrect software installation or draft software removal, or by failure to remove all files belonging to a deleted account, or other similar cases. The files should be repaired so they will not cause problems when accounts are created in the future, and the cause should be discovered and addressed. |
| CM-6(b) CM-6.1(iv) |
Ensure invoking users password for privilege escalation when using sudo |
The sudoers security policy requires that users authenticate themselves before they can use sudo.
When sudoers requires authentication, it validates the invoking user's credentials.
The expected output for:
sudo cvtsudoers -f sudoers /etc/sudoers | grep -E '^Defaults !?(rootpw|targetpw|runaspw)$' Defaults !targetpw
Defaults !rootpw
Defaults !runaspw
or if cvtsudoers not supported:
sudo find /etc/sudoers /etc/sudoers.d \( \! -name '*~' -a \! -name '*.*' \) -exec grep -E --with-filename '^[[:blank:]]*Defaults[[:blank:]](.*[[:blank:]])?!?\b(rootpw|targetpw|runaspw)' -- {} \;
/etc/sudoers:Defaults !targetpw
/etc/sudoers:Defaults !rootpw
/etc/sudoers:Defaults !runaspw
|
If the rootpw, targetpw, or runaspw flags are defined and not disabled, by default the operating system will prompt the invoking user for the "root" user password. |
| CM-6 | Disable core dump backtraces | The ProcessSizeMax option in [Coredump] section of /etc/systemd/coredump.conf specifies the maximum size in bytes of a core which will be processed. Core dumps exceeding this size may be stored, but the backtrace will not be generated. | A core dump includes a memory image taken at the time the operating system terminates an application. The memory image could contain sensitive data and is generally useful only for developers or system operators trying to debug problems. Enabling core dumps on production systems is not recommended, however there may be overriding operational requirements to enable advanced debuging. Permitting temporary enablement of core dumps during such situations should be reviewed through local needs and policy. |
| CM-6(a) AC-17(a) AC-2(5) AC-12 AC-17(a) SC-10 CM-6(a) |
Configure Logind to terminate idle sessions after certain time of inactivity |
To configure logind service to terminate inactive user sessions
after 300 seconds, edit the file
/etc/systemd/logind.conf. Ensure that there is a section
[Login]which contains the configuration StopIdleSessionSec=300. |
Terminating an idle session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been let unattended. |
| CM-6(b) CM-6.1(iv) |
System Must Avoid Meltdown and Spectre Exploit Vulnerabilities in Modern Processors |
Verify that Meltdown mitigations are not disabled:
$ sudo grubby --info=ALL | grep mitigationsThe mitigations must not be set to "off". |
Hardware vulnerabilities allow programs to steal data that is currently processed on the computer. While programs are typically not permitted to read data from other programs, a malicious program can exploit Meltdown and Spectre to obtain secrets stored in the memory of other running programs. This might include passwords stored in a password manager or browser; personal photos, emails, and instant messages; and business-critical documents. |
| CM-6(a) AC-6(1) |
Ensure All World-Writable Directories Are Owned by a System Account | All directories in local partitions which are world-writable should be owned by root or another system account. If any world-writable directories are not owned by a system account, this should be investigated. Following this, the files should be deleted or assigned to an appropriate owner. | Allowing a user account to own a world-writable directory is undesirable because it allows the owner of that directory to remove or replace any files that may be placed in the directory by other users. |
| CM-6(a) AC-6(1) |
Verify Group Who Owns /etc/cron.allow file |
If /etc/cron.allow exists, it must be group-owned by root.
To properly set the group owner of /etc/cron.allow, run the command:
$ sudo chgrp root /etc/cron.allow |
If the owner of the cron.allow file is not set to root, the possibility exists for an unauthorized user to view or edit sensitive information. |
| CM-6 | Set number of records to cause an explicit flush to audit logs | To configure Audit daemon to issue an explicit flush to disk command after writing 50 records, set freq to 50 in /etc/audit/auditd.conf. | If option freq isn't set to , the flush to disk may happen after higher number of records, increasing the danger of audit loss. |
| CM-6 | Write Audit Logs to the Disk | To configure Audit daemon to write Audit logs to the disk, set write_logs to yes in /etc/audit/auditd.conf. This is the default setting. | If write_logs isn't set to yes, the Audit logs will not be written to the disk. |
| AC-6 CM-6(a) CM-6(b) CM-6.1(iv) |
Ensure that System Accounts Do Not Run a Shell Upon Login |
Some accounts are not associated with a human user of the system, and exist to perform some
administrative functions. Should an attacker be able to log into these accounts, they should
not be granted access to a shell.
The login shell for each local account is stored in the last field of each line in /etc/passwd. System accounts are those user accounts with a user ID less than 1000. The user ID is stored in the third field. If any system account other than root has a login shell, disable it with the command: $ sudo usermod -s /sbin/nologin account |
Ensuring shells are not given to system accounts upon login makes it more difficult for attackers to make use of system accounts. |
| CM-6(a) AU-8(1)(b) AU-12(1) |
Configure Time Service Maxpoll Interval |
The maxpoll should be configured to
10 in /etc/ntp.conf or
/etc/chrony.conf (or /etc/chrony.d/) to continuously poll time servers. To configure
maxpoll in /etc/ntp.conf or /etc/chrony.conf (or /etc/chrony.d/)
add the following after each server, pool or peer entry:
maxpoll 10to server directives. If using chrony, any pool directives should be configured too. |
Inaccurate time stamps make it more difficult to correlate events and can lead to an inaccurate analysis. Determining the correct time a particular event occurred on a system is critical when conducting forensic analysis and investigating system events. Sources outside the configured acceptable allowance (drift) may be inaccurate. Synchronizing internal information system clocks provides uniformity of time stamps for information systems with multiple system clocks and systems connected over a network. Organizations should consider endpoints that may not have regular access to the authoritative time server (e.g., mobile, teleworking, and tactical endpoints). |
| CM-6(a) | Ensure Users Cannot Change GNOME3 Screensaver Idle Activation |
If not already configured, ensure that users cannot change GNOME3 screensaver lock settings
by adding /org/gnome/desktop/screensaver/idle-activation-enabledto /etc/dconf/db/local.d/00-security-settings. For example: /org/gnome/desktop/screensaver/idle-activation-enabledAfter the settings have been set, run dconf update. |
A session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not want to logout because of the temporary nature of the absense. |
| CM-6(a) AC-6(1) |
Verify Owner on cron.daily |
To properly set the owner of /etc/cron.daily, run the command:
$ sudo chown root /etc/cron.daily |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct user to prevent unauthorized changes. |
| CM-6 | Disable storing core dump | The Storage option in [Coredump] sectionof /etc/systemd/coredump.conf can be set to none to disable storing core dumps permanently. | A core dump includes a memory image taken at the time the operating system terminates an application. The memory image could contain sensitive data and is generally useful only for developers or system operators trying to debug problems. Enabling core dumps on production systems is not recommended, however there may be overriding operational requirements to enable advanced debuging. Permitting temporary enablement of core dumps during such situations should be reviewed through local needs and policy. |
| CM-6(a) IA-5(13) |
Configure SSSD to Expire SSH Known Hosts |
SSSD should be configured to expire keys from known SSH hosts after
180 seconds.
To configure SSSD to known SSH hosts, set ssh_known_hosts_timeout
to 180 under the
[ssh] section in /etc/sssd/sssd.conf. For example:
[ssh] ssh_known_hosts_timeout = 180 |
If cached authentication information is out-of-date, the validity of the authentication information may be questionable. |
| CM-6(a) AC-17(a) AC-17(2) SC-13 MA-4(6) IA-5(1)(c) SC-12(2) SC-12(3) |
Use Only FIPS 140-2 Validated Ciphers |
Limit the ciphers to those algorithms which are FIPS-approved.
Counter (CTR) mode is also preferred over cipher-block chaining (CBC) mode.
The following line in /etc/ssh/sshd_config
demonstrates use of FIPS-approved ciphers:
Ciphers aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc,aes192-cbc,aes256-cbcThe man page sshd_config(5) contains a list of supported ciphers. The rule is parametrized to use the following ciphers: aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc,aes192-cbc,aes256-cbc,rijndael-cbc@lysator.liu.se.
|
Unapproved mechanisms that are used for authentication to the cryptographic module are not verified and therefore
cannot be relied upon to provide confidentiality or integrity, and system data may be compromised.
Operating systems utilizing encryption are required to use FIPS-compliant mechanisms for authenticating to cryptographic modules. FIPS 140-2 is the current standard for validating that mechanisms used to access cryptographic modules utilize authentication that meets industry and government requirements. For government systems, this allows Security Levels 1, 2, 3, or 4 for use on Red Hat Enterprise Linux 8. |
| CM-6(a) AC-6(1) |
Enable Kernel Parameter to Enforce DAC on FIFOs |
To set the runtime status of the fs.protected_fifos kernel parameter, run the following command: $ sudo sysctl -w fs.protected_fifos=2To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: fs.protected_fifos = 2 |
This parameter is available since Linux Kernel 4.19 and allows to prohibit opening FIFOs that are not owned by the user in world and group writeable sticky directories. It avoids unintentional writes to an attacker-controlled FIFO where a program expects to create the regular file. |
| AC-6 (1) | Verify User Who Owns Backup gshadow File |
To properly set the owner of /etc/gshadow-, run the command: $ sudo chown root /etc/gshadow- |
The /etc/gshadow- file is a backup of /etc/gshadow, and as such, it contains group password hashes. Protection of this file is critical for system security. |
| CM-6(a) AC-6(1) |
Verify /boot/grub2/grub.cfg User Ownership |
The file /boot/grub2/grub.cfg should
be owned by the root user to prevent destruction
or modification of the file.
To properly set the owner of /boot/grub2/grub.cfg, run the command:
$ sudo chown root /boot/grub2/grub.cfg |
Only root should be able to modify important boot parameters. |
| AC-6 (1) | Verify Group Who Owns Backup shadow File |
To properly set the owner of /etc/shadow-, run the command: $ sudo chown root /etc/shadow- |
The /etc/shadow- file is a backup file of /etc/shadow, and as such, it contains the list of local system accounts and password hashes. Protection of this file is critical for system security. |
| CM-6(a) AC-6(1) |
Verify Permissions on shadow File |
To properly set the permissions of /etc/shadow, run the command:
$ sudo chmod 0000 /etc/shadow |
The /etc/shadow file contains the list of local system accounts and stores password hashes. Protection of this file is critical for system security. Failure to give ownership of this file to root provides the designated owner with access to sensitive information which could weaken the system security posture. |
| CM-6(a) | Install the opensc Package For Multifactor Authentication |
The opensc package can be installed with the following command:
$ sudo yum install opensc |
Using an authentication device, such as a CAC or token that is separate from
the information system, ensures that even if the information system is
compromised, that compromise will not affect credentials stored on the
authentication device.
Multifactor solutions that require devices separate from information systems gaining access include, for example, hardware tokens providing time-based or challenge-response authenticators and smart cards such as the U.S. Government Personal Identity Verification card and the DoD Common Access Card. |
| AC-6 AC-6(1) CM6(a) |
Mount Remote Filesystems with nosuid |
Add the nosuid option to the fourth column of /etc/fstab for the line which controls mounting of
any NFS mounts.
|
NFS mounts should not present suid binaries to users. Only vendor-supplied suid executables should be installed to their default location on the local filesystem. |
| CM-6(a) AC-7(a) |
Set Interval For Counting Failed Password Attempts | Utilizing pam_faillock.so, the fail_interval directive configures the system to lock out an account after a number of incorrect login attempts within a specified time period. Ensure that the file /etc/security/faillock.conf contains the following entry: fail_interval = <interval-in-seconds> where interval-in-seconds is 900 or greater. In order to avoid errors when manually editing these files, it is recommended to use the appropriate tools, such as authselect or authconfig, depending on the OS version. | By limiting the number of failed logon attempts the risk of unauthorized system access via user password guessing, otherwise known as brute-forcing, is reduced. Limits are imposed by locking the account. |
| CM-6(a) SC-5(2) |
Ensure /var Located On Separate Partition | The /var directory is used by daemons and other system services to store frequently-changing data. Ensure that /var has its own partition or logical volume at installation time, or migrate it using LVM. | Ensuring that /var is mounted on its own partition enables the setting of more restrictive mount options. This helps protect system services such as daemons or other programs which use it. It is not uncommon for the /var directory to contain world-writable directories installed by other software packages. |
| CM-6(a) AC-6(1) |
Verify Group Who Owns gshadow File |
To properly set the group owner of /etc/gshadow, run the command: $ sudo chgrp root /etc/gshadow |
The /etc/gshadow file contains group password hashes. Protection of this file is critical for system security. |
| CM-6(a) AC-6(1) |
Verify the UEFI Boot Loader grub.cfg Group Ownership |
The file /boot/efi/EFI/redhat/grub.cfg should
be group-owned by the root group to prevent
destruction or modification of the file.
To properly set the group owner of /boot/efi/EFI/redhat/grub.cfg, run the command:
$ sudo chgrp root /boot/efi/EFI/redhat/grub.cfg |
The root group is a highly-privileged group. Furthermore, the group-owner of this file should not have any access privileges anyway. |
| AC-6 | Disallow kernel profiling by unprivileged users |
To set the runtime status of the kernel.perf_event_paranoid kernel parameter, run the following command: $ sudo sysctl -w kernel.perf_event_paranoid=2To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: kernel.perf_event_paranoid = 2 |
Kernel profiling can reveal sensitive information about kernel behaviour. |
| CM-6 | Disable Kernel Image Loading |
To set the runtime status of the kernel.kexec_load_disabled kernel parameter, run the following command: $ sudo sysctl -w kernel.kexec_load_disabled=1To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: kernel.kexec_load_disabled = 1 |
Disabling kexec_load allows greater control of the kernel memory. It makes it impossible to load another kernel image after it has been disabled. |
| CM-6(a) | Install libreswan Package |
The libreswan package provides an implementation of IPsec
and IKE, which permits the creation of secure tunnels over
untrusted networks. The libreswan package can be installed with the following command:
$ sudo yum install libreswan |
Providing the ability for remote users or systems to initiate a secure VPN connection protects information when it is transmitted over a wide area network. |
| CM-6(a) AC-6(1) |
Ensure All SGID Executables Are Authorized | The SGID (set group id) bit should be set only on files that were installed via authorized means. A straightforward means of identifying unauthorized SGID files is determine if any were not installed as part of an RPM package, which is cryptographically verified. Investigate the origin of any unpackaged SGID files. This configuration check considers authorized SGID files those which were installed via RPM. It is assumed that when an individual has sudo access to install an RPM and all packages are signed with an organizationally-recognized GPG key, the software should be considered an approved package on the system. Any SGID file not deployed through an RPM will be flagged for further review. | Executable files with the SGID permission run with the privileges of the owner of the file. SGID files of uncertain provenance could allow for unprivileged users to elevate privileges. The presence of these files should be strictly controlled on the system. |
| CM-6 b | Verify Group Who Owns cron.deny |
To properly set the group owner of /etc/cron.deny, run the command:
$ sudo chgrp root /etc/cron.deny |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct group to prevent unauthorized changes. |
| CM-6(a) | Install the tmux Package |
To enable console screen locking, install the tmux package.
The tmux package can be installed with the following command:
$ sudo yum install tmuxA session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not want to log out because of the temporary nature of the absence. The session lock is implemented at the point where session activity can be determined. Rather than be forced to wait for a period of time to expire before the user session can be locked, Red Hat Enterprise Linux 8 needs to provide users with the ability to manually invoke a session lock so users can secure their session if it is necessary to temporarily vacate the immediate physical vicinity. Instruct users to begin new terminal sessions with the following command: $ tmuxThe console can now be locked with the following key combination: ctrl+b :lock-session |
A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate
physical vicinity of the information system but does not logout because of the temporary nature of the absence.
Rather than relying on the user to manually lock their operation system session prior to vacating the vicinity,
operating systems need to be able to identify when a user's session has idled and take action to initiate the
session lock.
The tmux package allows for a session lock to be implemented and configured. |
| CM-6(a) AC-17(a) AC-17(2) IA-5(1)(c) SC-13 MA-4(6) |
Allow Only SSH Protocol 2 |
Only SSH protocol version 2 connections should be
permitted. The default setting in
/etc/ssh/sshd_config is correct, and can be
verified by ensuring that the following
line appears:
Protocol 2 |
SSH protocol version 1 is an insecure implementation of the SSH protocol and has many well-known vulnerability exploits. Exploits of the SSH daemon could provide immediate root access to the system. |
| CM-6(a) | Enable SLUB/SLAB allocator poisoning | To enable poisoning of SLUB/SLAB objects, add the argument slub_debug=P to all BLS (Boot Loader Specification) entries ('options' line) for the Linux operating system in /boot/loader/entries/*.conf. | Poisoning writes an arbitrary value to freed objects, so any modification or reference to that object after being freed or before being initialized will be detected and prevented. This prevents many types of use-after-free vulnerabilities at little performance cost. Also prevents leak of data and detection of corrupted memory. |
| AC-6 CM-6(a) |
Restrict Virtual Console Root Logins |
To restrict root logins through the (deprecated) virtual console devices,
ensure lines of this form do not appear in /etc/securetty:
vc/1 vc/2 vc/3 vc/4 |
Preventing direct root login to virtual console devices helps ensure accountability for actions taken on the system using the root account. |
| CM-6(a) AU-8(1)(a) |
Chrony Configure Pool and Server |
Chrony is a daemon which implements the Network Time Protocol (NTP). It is designed to
synchronize system clocks across a variety of systems and use a source that is highly
accurate. More information on chrony can be found at
https://chrony-project.org/.
Chrony can be configured to be a client and/or a server.
Add or edit server or pool lines to /etc/chrony.conf as appropriate:
server <remote-server>Multiple servers may be configured. |
If chrony is in use on the system proper configuration is vital to ensuring time synchronization is working properly. |
| CM-6(a) | Enable cron Service |
The crond service is used to execute commands at
preconfigured times. It is required by almost all systems to perform necessary
maintenance tasks, such as notifying root of system activity.
The crond service can be enabled with the following command:
$ sudo systemctl enable crond.service |
Due to its usage for maintenance and security-supporting tasks, enabling the cron daemon is essential. |
| CM-6(a) | Install the systemd_timesyncd Service | The systemd_timesyncd service should be installed. | Time synchronization (using NTP) is required by almost all network and administrative tasks (syslog, cryptographic based services (authentication, etc.), etc.). systemd_timesyncd is a part of the systemd suite and acts as a NTP client. |
| AC-6 (1) | Verify Permissions on Backup gshadow File |
To properly set the permissions of /etc/gshadow-, run the command:
$ sudo chmod 0000 /etc/gshadow- |
The /etc/gshadow- file is a backup of /etc/gshadow, and as such, it contains group password hashes. Protection of this file is critical for system security. |
| CM-6(a) IA-5(13) |
Configure SSSD's Memory Cache to Expire |
SSSD's memory cache should be configured to set to expire records after
300 seconds.
To configure SSSD to expire memory cache, set memcache_timeout to
300 under the
[nss] section in /etc/sssd/sssd.conf.
For example:
[nss] memcache_timeout = 300 |
If cached authentication information is out-of-date, the validity of the authentication information may be questionable. |
| CM-6(a) | Enable cron Service |
The crond service is used to execute commands at
preconfigured times. It is required by almost all systems to perform necessary
maintenance tasks, such as notifying root of system activity.
The crond service can be enabled with the following command:
$ sudo systemctl enable crond.service |
Due to its usage for maintenance and security-supporting tasks, enabling the cron daemon is essential. |
| CM-6(a) AC-7(b) IA-5(c) |
Configure the root Account lock for Failed Password Attempts via pam_tally2 | This rule configures the system to lock out the root account after a number of incorrect login attempts using pam_tally2.so. | By limiting the number of failed logon attempts, the risk of unauthorized system access via user password guessing, also known as brute-forcing, is reduced. Limits are imposed by locking the account. |
| AC-6 SC-7(10) |
Disable Access to Network bpf() Syscall From Unprivileged Processes |
To set the runtime status of the kernel.unprivileged_bpf_disabled kernel parameter, run the following command: $ sudo sysctl -w kernel.unprivileged_bpf_disabled=1To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: kernel.unprivileged_bpf_disabled = 1 |
Loading and accessing the packet filters programs and maps using the bpf() syscall has the potential of revealing sensitive information about the kernel state. |
| CM-6(a) | Install firewalld Package |
The firewalld package can be installed with the following command:
$ sudo yum install firewalld |
"Firewalld" provides an easy and effective way to block/limit remote access to the system via ports, services, and protocols. Remote access services, such as those providing remote access to network devices and information systems, which lack automated control capabilities, increase risk and make remote user access management difficult at best. Remote access is access to DoD nonpublic information systems by an authorized user (or an information system) communicating through an external, non-organization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless. Red Hat Enterprise Linux 8 functionality (e.g., SSH) must be capable of taking enforcement action if the audit reveals unauthorized activity. Automated control of remote access sessions allows organizations to ensure ongoing compliance with remote access policies by enforcing connection rules of remote access applications on a variety of information system components (e.g., servers, workstations, notebook computers, smartphones, and tablets)." |
| AC-6 CM-6(a) |
Restrict Serial Port Root Logins |
To restrict root logins on serial ports,
ensure lines of this form do not appear in /etc/securetty:
ttyS0 ttyS1 |
Preventing direct root login to serial port interfaces helps ensure accountability for actions taken on the systems using the root account. |
| CM-6(a) | Enable page allocator poisoning |
To enable poisoning of free pages,
add the argument page_poison=1 to the default
GRUB 2 command line for the Linux operating system.
To ensure that page_poison=1 is added as a kernel command line
argument to newly installed kernels, add page_poison=1 to the
default Grub2 command line for Linux operating systems. Modify the line within
/etc/default/grub as shown below:
GRUB_CMDLINE_LINUX="... page_poison=1 ..."Run the following command to update command line for already installed kernels: # grubby --update-kernel=ALL --args="page_poison=1" |
Poisoning writes an arbitrary value to freed pages, so any modification or reference to that page after being freed or before being initialized will be detected and prevented. This prevents many types of use-after-free vulnerabilities at little performance cost. Also prevents leak of data and detection of corrupted memory. |
| CM-6(a) AC-6(1) |
Verify User Who Owns gshadow File |
To properly set the owner of /etc/gshadow, run the command: $ sudo chown root /etc/gshadow |
The /etc/gshadow file contains group password hashes. Protection of this file is critical for system security. |
| CM-6(a) | Install tcp_wrappers Package |
When network services are using the xinetd service, the
tcp_wrappers package should be installed.
The tcp_wrappers package can be installed with the following command:
$ sudo yum install tcp_wrappers |
Access control methods provide the ability to enhance system security posture by restricting services and known good IP addresses and address ranges. This prevents connections from unknown hosts and protocols. |
| CM-6(a) | Install the Policy Auditor (PA) Module | Install the Policy Auditor (PA) Module. | Without a host-based intrusion detection tool, there is no system-level defense when an intruder gains access to a system or network. Additionally, a host-based intrusion prevention tool can provide methods to immediately lock out detected intrusion attempts. |
| CM-6(a) | Set the UEFI Boot Loader Password |
The grub2 boot loader should have a superuser account and password
protection enabled to protect boot-time settings.
Since plaintext passwords are a security risk, generate a hash for the password by running the following command: # grub2-setpasswordWhen prompted, enter the password that was selected. |
Password protection on the boot loader configuration ensures users with physical access cannot trivially alter important bootloader settings. These include which kernel to use, and whether to enter single-user mode. |
| CM-6(a) AC-7(a) |
Lock Accounts After Failed Password Attempts | This rule configures the system to lock out accounts after a number of incorrect login attempts using pam_faillock.so. pam_faillock.so module requires multiple entries in pam files. These entries must be carefully defined to work as expected. Ensure that the file /etc/security/faillock.conf contains the following entry: deny = <count> Where count should be less than or equal to 3 and greater than 0. In order to avoid errors when manually editing these files, it is recommended to use the appropriate tools, such as authselect or authconfig, depending on the OS version. | By limiting the number of failed logon attempts, the risk of unauthorized system access via user password guessing, also known as brute-forcing, is reduced. Limits are imposed by locking the account. |
| CM-6(a) AC-6(1) |
Ensure All World-Writable Directories Are Group Owned by a System Account | All directories in local partitions which are world-writable should be group owned by root or another system account. If any world-writable directories are not group owned by a system account, this should be investigated. Following this, the files should be deleted or assigned to an appropriate group. | Allowing a user account to group own a world-writable directory is undesirable because it allows the owner of that directory to remove or replace any files that may be placed in the directory by other users. |
| CM-6(a) SC-28 SC-28(1) SC-13 AU-9(3) |
Encrypt Partitions |
Red Hat Enterprise Linux 8 natively supports partition encryption through the
Linux Unified Key Setup-on-disk-format (LUKS) technology. The easiest way to
encrypt a partition is during installation time.
For manual installations, select the Encrypt checkbox during partition creation to encrypt the partition. When this option is selected the system will prompt for a passphrase to use in decrypting the partition. The passphrase will subsequently need to be entered manually every time the system boots. For automated/unattended installations, it is possible to use Kickstart by adding the --encrypted and --passphrase= options to the definition of each partition to be encrypted. For example, the following line would encrypt the root partition: part / --fstype=ext4 --size=100 --onpart=hda1 --encrypted --passphrase=PASSPHRASEAny PASSPHRASE is stored in the Kickstart in plaintext, and the Kickstart must then be protected accordingly. Omitting the --passphrase= option from the partition definition will cause the installer to pause and interactively ask for the passphrase during installation. By default, the Anaconda installer uses aes-xts-plain64 cipher with a minimum 512 bit key size which should be compatible with FIPS enabled. Detailed information on encrypting partitions using LUKS or LUKS ciphers can be found on the Red Hat Enterprise Linux 8 Documentation web site: https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/security_hardening/encrypting-block-devices-using-luks_security-hardening . |
The risk of a system's physical compromise, particularly mobile systems such as laptops, places its data at risk of compromise. Encrypting this data mitigates the risk of its loss if the system is lost. |
| CM-6(a) CM-6(a) |
Ensure that Root's Path Does Not Include World or Group-Writable Directories |
For each element in root's path, run:
# ls -ld DIRand ensure that write permissions are disabled for group and other. |
Such entries increase the risk that root could execute code provided by unprivileged users, and potentially malicious code. |
| CM-6(a) AU-8(1)(a) |
Specify a Remote NTP Server |
To specify a remote NTP server for time synchronization, edit
the file /etc/ntp.conf. Add or correct the following lines,
substituting the IP or hostname of a remote NTP server for ntpserver:
server ntpserverThis instructs the NTP software to contact that remote server to obtain time data. |
Synchronizing with an NTP server makes it possible to collate system logs from multiple sources or correlate computer events with real time events. |
| AC-6 (1) | Verify Permissions on Backup shadow File |
To properly set the permissions of /etc/shadow-, run the command:
$ sudo chmod 0000 /etc/shadow- |
The /etc/shadow- file is a backup file of /etc/shadow, and as such, it contains the list of local system accounts and password hashes. Protection of this file is critical for system security. |
| CM-6(a) | Disable DHCP Client in ifcfg |
For each interface on the system (e.g. eth0), edit
/etc/sysconfig/network-scripts/ifcfg-interface and make the
following changes:
|
DHCP relies on trusting the local network. If the local network is not trusted, then it should not be used. However, the automatic configuration provided by DHCP is commonly used and the alternative, manual configuration, presents an unacceptable burden in many circumstances. |
| CM-6(a) | Ensure Users Cannot Change GNOME3 Screensaver Settings |
If not already configured, ensure that users cannot change GNOME3 screensaver lock settings
by adding /org/gnome/desktop/screensaver/lock-delay
to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification.
For example:
/org/gnome/desktop/screensaver/lock-delayAfter the settings have been set, run dconf update. |
A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not logout because of the temporary nature of the absence. Rather than relying on the user to manually lock their operating system session prior to vacating the vicinity, GNOME desktops can be configured to identify when a user's session has idled and take action to initiate the session lock. As such, users should not be allowed to change session settings. |
| CM-6(a) AC-6(1) |
Set Daemon Umask |
The file /etc/init.d/functions includes initialization
parameters for most or all daemons started at boot time. Many daemons
on the system already individually restrict themselves to
a umask of 077 in their own init scripts. By default, the umask of
022 is set which prevents creation of group- or world-writable files.
To set the umask for daemons expected by the profile, edit the following line:
umask 022 |
The umask influences the permissions assigned to files created by a process at run time. An unnecessarily permissive umask could result in files being created with insecure permissions. |
| CM-6(a) AU-8(1)(a) AU-12(1) |
Enable the NTP Daemon |
Run the following command to determine the current status of the
chronyd service:
$ sudo systemctl is-active chronydIf the service is running, it should return the following: activeNote: The chronyd daemon is enabled by default. Run the following command to determine the current status of the ntpd service:
$ sudo systemctl is-active ntpdIf the service is running, it should return the following: activeNote: The ntpd daemon is not enabled by default. Though as mentioned in the previous sections in certain environments the ntpd daemon might be preferred to be used rather than the chronyd one. Refer to: https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/system_administrators_guide/ch-configuring_ntp_using_the_chrony_suite for guidance which NTP daemon to choose depending on the environment used. |
Enabling some of chronyd or ntpd services ensures
that the NTP daemon will be running and that the system will synchronize its
time to any servers specified. This is important whether the system is
configured to be a client (and synchronize only its own clock) or it is also
acting as an NTP server to other systems. Synchronizing time is essential for
authentication services such as Kerberos, but it is also important for
maintaining accurate logs and auditing possible security breaches.
The chronyd and ntpd NTP daemons offer all of the functionality of ntpdate, which is now deprecated. |
| CM-6 | Prevent user from disabling the screen lock | The tmux terminal multiplexer is used to implement automatic session locking. It should not be listed in /etc/shells. | Not listing tmux among permitted shells prevents malicious program running as user from lowering security by disabling the screen lock. |
| CM-6(a) AC-6(1) AU-9(4) |
System Audit Logs Must Have Mode 0640 or Less Permissive |
Determine where the audit logs are stored with the following command:
$ sudo grep -iw log_file /etc/audit/auditd.conf log_file = /var/log/audit/audit.logConfigure the audit log to be protected from unauthorized read access by setting the correct permissive mode with the following command: $ sudo chmod 0600 audit_log_fileBy default, audit_log_file is "/var/log/audit/audit.log". |
If users can write to audit logs, audit trails can be modified or destroyed. |
| CM-6(a) IA-5(10) |
Enable the SSSD Service |
The SSSD service should be enabled.
The sssd service can be enabled with the following command:
$ sudo systemctl enable sssd.service |
|
| CM-6(a) AC-6(1) |
Verify /boot/grub2/grub.cfg Group Ownership |
The file /boot/grub2/grub.cfg should
be group-owned by the root group to prevent
destruction or modification of the file.
To properly set the group owner of /boot/grub2/grub.cfg, run the command:
$ sudo chgrp root /boot/grub2/grub.cfg |
The root group is a highly-privileged group. Furthermore, the group-owner of this file should not have any access privileges anyway. |
| CM-6(a) AC-17(a) AC-17(2) |
Enable Encrypted X11 Forwarding |
By default, remote X11 connections are not encrypted when initiated
by users. SSH has the capability to encrypt remote X11 connections when SSH's
X11Forwarding option is enabled.
To enable X11 Forwarding, add or correct the following line in /etc/ssh/sshd_config: X11Forwarding yes |
Non-encrypted X displays allow an attacker to capture keystrokes and to execute commands remotely. |
| CM-6(a) AC-6(1) AU-9 |
System Audit Logs Must Have Mode 0750 or Less Permissive |
Verify the audit log directories have a mode of "0700" or less permissive by first determining
where the audit logs are stored with the following command:
$ sudo grep -iw log_file /etc/audit/auditd.conf log_file = /var/log/audit/audit.logConfigure the audit log directory to be protected from unauthorized read access by setting the correct permissive mode with the following command: $ sudo chmod 0700 audit_log_directoryBy default, audit_log_directory is "/var/log/audit". |
If users can write to audit logs, audit trails can be modified or destroyed. |
| AC-6 (1) | Verify Group Who Owns Backup group File |
To properly set the group owner of /etc/group-, run the command: $ sudo chgrp root /etc/group- |
The /etc/group- file is a backup file of /etc/group, and as such, it contains information regarding groups that are configured on the system. Protection of this file is important for system security. |
| CM-6(a) AC-6(1) |
Verify Permissions on crontab |
To properly set the permissions of /etc/crontab, run the command:
$ sudo chmod 0600 /etc/crontab |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should have the correct access rights to prevent unauthorized changes. |
| CM-6(a) | Install sudo Package |
The sudo package can be installed with the following command:
$ sudo yum install sudo |
sudo is a program designed to allow a system administrator to give limited root privileges to users and log root activity. The basic philosophy is to give as few privileges as possible but still allow system users to get their work done. |
| CM-6 b CM-6.1(iv) |
Grant Or Deny System Access To Specific Hosts And Services |
To verify the system's access control program is configured
to grant or deny system access to specific hosts check to see
if "firewalld" is active with the following command:
# systemctl status firewalld firewalld.service - firewalld - dynamic firewall daemon Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled) Active: active (running) since Sun 2014-04-20 14:06:46 BST; 30s agoIf "firewalld" is active, check to see if it is configured to grant or deny access to specific hosts or services with the following commands: # firewall-cmd --get-default-zone public # firewall-cmd --list-all --zone=public public (active) target: default icmp-block-inversion: no interfaces: eth0 sources: services: mdns ssh ports: protocols: masquerade: no forward-ports: icmp-blocks:If "firewalld" is not active, determine whether "tcpwrappers" is being used by checking whether the "hosts.allow" and "hosts.deny" files are empty with the following commands: # ls -al /etc/hosts.allow rw-r----- 1 root root 9 Aug 2 23:13 /etc/hosts.allow # ls -al /etc/hosts.deny -rw-r----- 1 root root 9 Apr 9 2007 /etc/hosts.denyIf "firewalld" and "tcpwrappers" are not installed, configured, and active, ask the SA if another access control program (such as iptables) is installed and active. Ask the SA to show that the running configuration grants or denies access to specific hosts or services. If "firewalld" is active and is not configured to grant access to specific hosts or "tcpwrappers" is not configured to grant or deny access to specific hosts, this is a finding. |
If the systems access control program is not configured with appropriate rules for allowing and denying access to system network resources, services may be accessible to unauthorized hosts. |
| CM-6(a) AC-6(1) |
Verify User Who Owns /etc/cron.allow file |
If /etc/cron.allow exists, it must be owned by root.
To properly set the owner of /etc/cron.allow, run the command:
$ sudo chown root /etc/cron.allow |
If the owner of the cron.allow file is not set to root, the possibility exists for an unauthorized user to view or edit sensitive information. |
| CM-6(a) AC-6(1) |
Verify /boot/grub2/grub.cfg Permissions |
File permissions for /boot/grub2/grub.cfg should be set to 600.
To properly set the permissions of /boot/grub2/grub.cfg, run the command:
$ sudo chmod 600 /boot/grub2/grub.cfg |
Proper permissions ensure that only the root user can modify important boot parameters. |
| CM-6(d) CM-6(c) SI-7 SI-7(1) SI-7(6) AU-9(3) |
Verify and Correct Ownership with RPM |
The RPM package management system can check file ownership permissions of installed software
packages, including many that are important to system security. After locating a file with
incorrect permissions, which can be found with:
rpm -Va | awk '{ if (substr($0,6,1)=="U" || substr($0,7,1)=="G") print $NF }'
run the following command to determine which package owns it:
$ rpm -qf FILENAMENext, run the following command to reset its permissions to the correct values: $ sudo rpm --restore PACKAGENAME |
Ownership of binaries and configuration files that is incorrect could allow an unauthorized user to gain privileges that they should not have. The ownership set by the vendor should be maintained. Any deviations from this baseline should be investigated. |
| CM-6 | Disable debug-shell SystemD Service |
SystemD's debug-shell service is intended to
diagnose SystemD related boot issues with various systemctl
commands. Once enabled and following a system reboot, the root shell
will be available on tty9 which is access by pressing
CTRL-ALT-F9. The debug-shell service should only be used
for SystemD related issues and should otherwise be disabled.
By default, the debug-shell SystemD service is already disabled. The debug-shell service can be disabled with the following command:
$ sudo systemctl mask --now debug-shell.service |
This prevents attackers with physical access from trivially bypassing security on the machine through valid troubleshooting configurations and gaining root access when the system is rebooted. |
| CM-6 SC-7(10) |
Disable Core Dumps for All Users |
To disable core dumps for all users, add the following line to
/etc/security/limits.conf, or to a file within the
/etc/security/limits.d/ directory:
* hard core 0 |
A core dump includes a memory image taken at the time the operating system terminates an application. The memory image could contain sensitive data and is generally useful only for developers trying to debug problems. |
| CM-6(a) AC-6(1) |
Verify Group Who Owns cron.monthly |
To properly set the group owner of /etc/cron.monthly, run the command:
$ sudo chgrp root /etc/cron.monthly |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct group to prevent unauthorized changes. |
| CM-6(a) AU-8(1)(a) AU-8(2) AU-12(1) |
Specify Additional Remote NTP Servers |
Depending on specific functional requirements of a concrete
production environment, the Red Hat Enterprise Linux 8 system can be
configured to utilize the services of the chronyd NTP daemon (the
default), or services of the ntpd NTP daemon. Refer to
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/system_administrators_guide/ch-configuring_ntp_using_the_chrony_suite
for more detailed comparison of the features of both of the choices, and for
further guidance how to choose between the two NTP daemons.
Additional NTP servers can be specified for time synchronization. To do so, perform the following:
server ntpserver |
Specifying additional NTP servers increases the availability of accurate time data, in the event that one of the specified servers becomes unavailable. This is typical for a system acting as an NTP server for other systems. |
| CM-6(a) | Set the Boot Loader Admin Username to a Non-Default Value |
The grub2 boot loader should have a superuser account and password
protection enabled to protect boot-time settings.
To maximize the protection, select a password-protected superuser account with unique name, and modify the /etc/grub.d/01_users configuration file to reflect the account name change. Do not to use common administrator account names like root, admin, or administrator for the grub2 superuser account. Change the superuser to a different username (The default is 'root'). $ sed -i 's/\(set superusers=\).*/\1"<unique user ID>"/g' /etc/grub.d/01_users Once the superuser account has been added, update the grub.cfg file by running: grubby --update-kernel=ALL --env=/boot/grub2/grubenv |
Having a non-default grub superuser username makes password-guessing attacks less effective. |
| CM-6(a) AC-6(1) |
Verify Permissions on cron.monthly |
To properly set the permissions of /etc/cron.monthly, run the command:
$ sudo chmod 0700 /etc/cron.monthly |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should have the correct access rights to prevent unauthorized changes. |
| CM-6(a) AC-6(1) |
Verify Owner on crontab |
To properly set the owner of /etc/crontab, run the command:
$ sudo chown root /etc/crontab |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct user to prevent unauthorized changes. |
| CM-6(a) AC-6(1) |
Ensure Log Files Are Owned By Appropriate User |
The owner of all log files written by
rsyslog should be
root.
These log files are determined by the second part of each Rule line in
/etc/rsyslog.conf and typically all appear in /var/log.
For each log file LOGFILE referenced in /etc/rsyslog.conf,
run the following command to inspect the file's owner:
$ ls -l LOGFILEIf the owner is not root, run the following command to correct this: $ sudo chown root LOGFILE |
The log files generated by rsyslog contain valuable information regarding system configuration, user authentication, and other such information. Log files should be protected from unauthorized access. |
| CM-6(a) AC-7(a) IA-5(4) |
Ensure PAM Enforces Password Requirements - Authentication Retry Prompts Permitted Per-Session | To configure the number of retry prompts that are permitted per-session: Edit the /etc/security/pwquality.conf to include retry=3, or a lower value if site policy is more restrictive. The DoD requirement is a maximum of 3 prompts per session. | Setting the password retry prompts that are permitted on a per-session basis to a low value requires some software, such as SSH, to re-connect. This can slow down and draw additional attention to some types of password-guessing attacks. Note that this is different from account lockout, which is provided by the pam_faillock module. |
| CM-6(a) AC-6(1) |
Verify Group Who Owns cron.d |
To properly set the group owner of /etc/cron.d, run the command:
$ sudo chgrp root /etc/cron.d |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct group to prevent unauthorized changes. |
| CM-6(a) CM-6(a) |
Ensure that Root's Path Does Not Include Relative Paths or Null Directories |
Ensure that none of the directories in root's path is equal to a single
. character, or
that it contains any instances that lead to relative path traversal, such as
.. or beginning a path without the slash (/) character.
Also ensure that there are no "empty" elements in the path, such as in these examples:
PATH=:/bin PATH=/bin: PATH=/bin::/sbinThese empty elements have the same effect as a single . character. |
Including these entries increases the risk that root could execute code from an untrusted location. |
| CM-6(a) AC-7(b) |
Set Lockout Time for Failed Password Attempts | This rule configures the system to lock out accounts during a specified time period after a number of incorrect login attempts using pam_faillock.so. Ensure that the file /etc/security/faillock.conf contains the following entry: unlock_time=<interval-in-seconds> where interval-in-seconds is 0 or greater. pam_faillock.so module requires multiple entries in pam files. These entries must be carefully defined to work as expected. In order to avoid any errors when manually editing these files, it is recommended to use the appropriate tools, such as authselect or authconfig, depending on the OS version. If unlock_time is set to 0, manual intervention by an administrator is required to unlock a user. This should be done using the faillock tool. | By limiting the number of failed logon attempts the risk of unauthorized system access via user password guessing, otherwise known as brute-forcing, is reduced. Limits are imposed by locking the account. |
| CM-6(a) AC-6(1) CM-7(b) |
Disable Ctrl-Alt-Del Reboot Key Sequence in GNOME3 |
By default, GNOME will reboot the system if the
Ctrl-Alt-Del key sequence is pressed.
To configure the system to ignore the Ctrl-Alt-Del key sequence from the Graphical User Interface (GUI) instead of rebooting the system, add or set logout to [''] in /etc/dconf/db/local.d/00-security-settings. For example: [org/gnome/settings-daemon/plugins/media-keys] logout=['']Once the settings have been added, add a lock to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification. For example: /org/gnome/settings-daemon/plugins/media-keys/logoutAfter the settings have been set, run dconf update. |
A locally logged-in user who presses Ctrl-Alt-Del, when at the console, can reboot the system. If accidentally pressed, as could happen in the case of mixed OS environment, this can create the risk of short-term loss of availability of systems due to unintentional reboot. |
| CM-6(a) | Root Path Must Be Vendor Default |
Assuming root shell is bash, edit the following files:
~/.profile ~/.bashrcChange any PATH variables to the vendor default for root and remove any empty PATH entries or references to relative paths. |
The root account's executable search path must be the vendor default, and must contain only absolute paths. |
| CM-6(a) | Install Virus Scanning Software | Virus scanning software can be used to protect a system from penetration from computer viruses and to limit their spread through intermediate systems. The virus scanning software should be configured to perform scans dynamically on accessed files. If this capability is not available, the system must be configured to scan, at a minimum, all altered files on the system on a daily basis. If the system processes inbound SMTP mail, the virus scanner must be configured to scan all received mail. | Virus scanning software can be used to detect if a system has been compromised by computer viruses, as well as to limit their spread to other systems. |
| CM-6(a) SC-28 SI-3(a) |
Enable nails Service |
The nails service is used to run McAfee VirusScan Enterprise
for Linux and McAfee Host-based Security System (HBSS) services.
The nails service can be enabled with the following command:
$ sudo systemctl enable nails.service |
Virus scanning software can be used to detect if a system has been compromised by computer viruses, as well as to limit their spread to other systems. |
| CM-6(d) CM-6(c) SI-7 SI-7(1) SI-7(6) AU-9(3) |
Verify File Hashes with RPM |
Without cryptographic integrity protections, system executables and files can be altered by
unauthorized users without detection. The RPM package management system can check the hashes
of installed software packages, including many that are important to system security.
To verify that the cryptographic hash of system files and commands matches vendor values, run
the following command to list which files on the system have hashes that differ from what is
expected by the RPM database:
$ rpm -Va --noconfig | grep '^..5'If the file was not expected to change, investigate the cause of the change using audit logs or other means. The package can then be reinstalled to restore the file. Run the following command to determine which package owns the file: $ rpm -qf FILENAMEThe package can be reinstalled from a yum repository using the command: $ sudo yum reinstall PACKAGENAMEAlternatively, the package can be reinstalled from trusted media using the command: $ sudo rpm -Uvh PACKAGENAME |
The hashes of important files like system executables should match the information given by the RPM database. Executables with erroneous hashes could be a sign of nefarious activity on the system. |
| CM-6(a) | Install iptables-services Package |
The iptables-services package can be installed with the following command:
$ sudo yum install iptables-services |
iptables-services provides the services iptables and ip6tables that have been split out of the base package since they are not active by default anymore. These services load the iptables rules during the system startup and also allow one to reload the iptables rules during runtime. |
| CM-6(a) AC-6(1) |
Verify Group Who Owns group File |
To properly set the group owner of /etc/group, run the command: $ sudo chgrp root /etc/group |
The /etc/group file contains information regarding groups that are configured on the system. Protection of this file is important for system security. |
| CM-6(a) | Configure Certificate Directives for LDAP Use of TLS |
Ensure a copy of a trusted CA certificate has been placed in the file
/etc/pki/tls/CA/cacert.pem. Configure LDAP to enforce TLS use and
to trust certificates signed by that CA. First, edit the file
/etc/nslcd.conf, and add or correct either of the following lines:
tls_cacertdir /etc/pki/tls/CAor tls_cacertfile /etc/pki/tls/CA/cacert.pemThen review the LDAP server and ensure TLS has been configured. |
The tls_cacertdir or tls_cacertfile directives are required when tls_checkpeer is configured (which is the default for openldap versions 2.1 and up). These directives define the path to the trust certificates signed by the site CA. |
| CM-6(a) SC-5(2) |
Ensure /home Located On Separate Partition | If user home directories will be stored locally, create a separate partition for /home at installation time (or migrate it later using LVM). If /home will be mounted from another system such as an NFS server, then creating a separate partition is not necessary at installation time, and the mountpoint can instead be configured later. | Ensuring that /home is mounted on its own partition enables the setting of more restrictive mount options, and also helps ensure that users cannot trivially fill partitions used for log or audit data storage. |
| CM-6 b | fapolicyd Must be Configured to Limit Access to Users Home Folders | fapolicyd needs be configured so that users cannot give access to their home folders to other users. | Users' home directories/folders may contain information of a sensitive nature. Non-privileged users should coordinate any sharing of information with a System Administrator (SA) through shared resources. fapolicyd can confine users to their home directory, not allowing them to make any changes outside of their own home directories. Confining users to their home directory will minimize the risk of sharing information. |
| CM-6(a) AU-8(1)(a) |
Enable systemd_timesyncd Service |
The systemd_timesyncd service can be enabled with the following command:
$ sudo systemctl enable systemd_timesyncd.service |
Enabling the systemd_timesyncd service ensures that this host
uses the ntp protocol to fetch time data from a ntp server.
Synchronizing time is essential for authentication
services such as Kerberos, but it is also important for maintaining accurate
logs and auditing possible security breaches.
Additional information on Ubuntu network time protocol is available at https://help.ubuntu.com/lts/serverguide/NTP.html.en. |
| CM-6(a) AC-6(1) |
Verify the UEFI Boot Loader grub.cfg Permissions |
File permissions for /boot/efi/EFI/redhat/grub.cfg should be set to 700.
To properly set the permissions of /boot/efi/EFI/redhat/grub.cfg, run the command:
$ sudo chmod 700 /boot/efi/EFI/redhat/grub.cfg |
Proper permissions ensure that only the root user can modify important boot parameters. |
| CM-6(a) AC-6(1) |
Verify the UEFI Boot Loader grub.cfg User Ownership |
The file /boot/efi/EFI/redhat/grub.cfg should
be owned by the root user to prevent destruction
or modification of the file.
To properly set the owner of /boot/efi/EFI/redhat/grub.cfg, run the command:
$ sudo chown root /boot/efi/EFI/redhat/grub.cfg |
Only root should be able to modify important boot parameters. |
| CM-6(b) | NetworkManager DNS Mode Must Be Must Configured | The DNS processing mode in NetworkManager describes how DNS is processed on the system. Depending the mode some changes the system's DNS may not be respected. | To ensure that DNS resolver settings are respected, a DNS mode in NetworkManager must be configured. |
| CM-6(a) AC-6(1) |
Verify Permissions on passwd File |
To properly set the permissions of /etc/passwd, run the command:
$ sudo chmod 0644 /etc/passwd |
If the /etc/passwd file is writable by a group-owner or the world the risk of its compromise is increased. The file contains the list of accounts on the system and associated information, and protection of this file is critical for system security. |
| CM-6(a) AC-17(a) AC-6 |
Enable Use of Privilege Separation |
When enabled, SSH will create an unprivileged child process that
has the privilege of the authenticated user. To enable privilege separation in
SSH, add or correct the following line in the /etc/ssh/sshd_config file:
UsePrivilegeSeparation sandbox |
SSH daemon privilege separation causes the SSH process to drop root privileges when not needed which would decrease the impact of software vulnerabilities in the unprivileged section. |
| CM-6(a) AC-6(1) |
Enable Kernel Parameter to Enforce DAC on Symlinks |
To set the runtime status of the fs.protected_symlinks kernel parameter, run the following command: $ sudo sysctl -w fs.protected_symlinks=1To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: fs.protected_symlinks = 1 |
By enabling this kernel parameter, symbolic links are permitted to be followed only when outside a sticky world-writable directory, or when the UID of the link and follower match, or when the directory owner matches the symlink's owner. Disallowing such symlinks helps mitigate vulnerabilities based on insecure file system accessed by privileged programs, avoiding an exploitation vector exploiting unsafe use of open() or creat(). |
| CM-6 AU-3 |
Set type of computer node name logging in audit logs | To configure Audit daemon to use a unique identifier as computer node name in the audit events, set name_format to hostname in /etc/audit/auditd.conf. | If option name_format is left at its default value of none, audit events from different computers may be hard to distinguish. |
| CM-6(a) AC-6(1) |
Verify Group Who Owns cron.hourly |
To properly set the group owner of /etc/cron.hourly, run the command:
$ sudo chgrp root /etc/cron.hourly |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct group to prevent unauthorized changes. |
| CM-6(a) | Ensure cron Is Logging To Rsyslog |
Cron logging must be implemented to spot intrusions or trace
cron job status. If cron is not logging to rsyslog, it
can be implemented by adding the following to the RULES section of
/etc/rsyslog.conf:
If the legacy syntax is used:
cron.* /var/log/cronIf the modern syntax (RainerScript) is used: cron.* action(type="omfile" file="/var/log/cron") |
Cron logging can be used to trace the successful or unsuccessful execution of cron jobs. It can also be used to spot intrusions into the use of the cron facility by unauthorized and malicious users. |
| CM-6(b) CM-6(iv) |
The operating system must restrict privilege elevation to authorized personnel | The sudo command allows a user to execute programs with elevated (administrator) privileges. It prompts the user for their password and confirms your request to execute a command by checking a file, called sudoers. Restrict privileged actions by removing the following entries from the sudoers file: ALL ALL=(ALL) ALL ALL ALL=(ALL:ALL) ALL | If the "sudoers" file is not configured correctly, any user defined on the system can initiate privileged actions on the target system. |
| CM-6(a) AC-6(1) |
Verify /boot/efi/EFI/redhat/user.cfg Permissions |
File permissions for /boot/efi/EFI/redhat/user.cfg should be set to 600.
To properly set the permissions of /boot/efi/EFI/redhat/user.cfg, run the command:
$ sudo chmod 600 /boot/efi/EFI/redhat/user.cfg |
Proper permissions ensure that only the root user can read or modify important boot parameters. |
| AC-6 AC-6(8) AC-6(10) CM-6(a) |
Mount Remote Filesystems with noexec |
Add the noexec option to the fourth column of /etc/fstab for the line which controls mounting of
any NFS mounts.
|
The noexec mount option causes the system not to execute binary files. This option must be used for mounting any file system not containing approved binary files as they may be incompatible. Executing files from untrusted file systems increases the opportunity for unprivileged users to attain unauthorized administrative access. |
| CM-6(a) | Enable GNOME3 Screensaver Lock After Idle Period |
To activate locking of the screensaver in the GNOME3 desktop when it is activated,
add or set lock-enabled to true in
/etc/dconf/db/local.d/00-security-settings. For example:
[org/gnome/desktop/screensaver] lock-enabled=trueOnce the settings have been added, add a lock to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification. For example: /org/gnome/desktop/screensaver/lock-enabledAfter the settings have been set, run dconf update. |
A session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not want to logout because of the temporary nature of the absense. |
| CM-6(a) CM-5(6) CM-5(6).1 AC-6(1) |
Verify that Shared Library Files Have Restrictive Permissions |
System-wide shared library files, which are linked to executables
during process load time or run time, are stored in the following directories
by default:
/lib /lib64 /usr/lib /usr/lib64Kernel modules, which can be added to the kernel during runtime, are stored in /lib/modules. All files in these directories should not be group-writable or world-writable. If any file in these directories is found to be group-writable or world-writable, correct its permission with the following command: $ sudo chmod go-w FILE |
Files from shared library directories are loaded into the address space of processes (including privileged ones) or of the kernel itself at runtime. Restrictive permissions are necessary to protect the integrity of the system. |
| CM-6(a) AC-6(1) |
Verify Group Who Owns cron.daily |
To properly set the group owner of /etc/cron.daily, run the command:
$ sudo chgrp root /etc/cron.daily |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct group to prevent unauthorized changes. |
| CM-6 | Include Local Events in Audit Logs | To configure Audit daemon to include local events in Audit logs, set local_events to yes in /etc/audit/auditd.conf. This is the default setting. | If option local_events isn't set to yes only events from network will be aggregated. |
| CM-6(a) AC-6(1) |
Verify /boot/efi/EFI/redhat/user.cfg User Ownership |
The file /boot/efi/EFI/redhat/user.cfg should be owned by the root
user to prevent reading or modification of the file.
To properly set the owner of /boot/efi/EFI/redhat/user.cfg, run the command:
$ sudo chown root /boot/efi/EFI/redhat/user.cfg |
Only root should be able to modify important boot parameters. Also, non-root users who read the boot parameters may be able to identify weaknesses in security upon boot and be able to exploit them. |
| CM-6(a) | Install the cron service | The Cron service should be installed. | The cron service allow periodic job execution, needed for almost all administrative tasks and services (software update, log rotating, etc.). Access to cron service should be restricted to administrative accounts only. |
| CM-6(a) | Install the OpenSSH Server Package |
The openssh-server package should be installed.
The openssh-server package can be installed with the following command:
$ sudo yum install openssh-server |
Without protection of the transmitted information, confidentiality, and integrity may be compromised because unprotected communications can be intercepted and either read or altered. |
| CM-6(a) | Install strongswan Package |
The Strongswan package provides an implementation of IPsec
and IKE, which permits the creation of secure tunnels over
untrusted networks. The strongswan package can be installed with the following command:
$ sudo yum install strongswan |
Providing the ability for remote users or systems to initiate a secure VPN connection protects information when it is transmitted over a wide area network. |
| CM-6(a) AC-6(1) |
Enable Kernel Parameter to Enforce DAC on Hardlinks |
To set the runtime status of the fs.protected_hardlinks kernel parameter, run the following command: $ sudo sysctl -w fs.protected_hardlinks=1To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: fs.protected_hardlinks = 1 |
By enabling this kernel parameter, users can no longer create soft or hard links to files which they do not own. Disallowing such hardlinks mitigate vulnerabilities based on insecure file system accessed by privileged programs, avoiding an exploitation vector exploiting unsafe use of open() or creat(). |
| CM-6(b) AC-6 CM-7(a) |
Ensure tftp Daemon Uses Secure Mode |
If running the Trivial File Transfer Protocol (TFTP) service is necessary,
it should be configured to change its root directory at startup. To do so,
ensure /etc/xinetd.d/tftp includes -s as a command line argument,
as shown in the following example:
server_args = -s /var/lib/tftpboot |
Using the -s option causes the TFTP service to only serve files from the given directory. Serving files from an intentionally-specified directory reduces the risk of sharing files which should remain private. |
| CM-6(a) AC-6(1) |
Ensure All Files Are Owned by a Group |
If any file is not group-owned by a group present in /etc/group, the cause of the lack of
group-ownership must be investigated. Following this, those files should be deleted or
assigned to an appropriate group.
Locate the mount points related to local devices by the following command:
$ findmnt -n -l -k -it $(awk '/nodev/ { print $2 }' /proc/filesystems | paste -sd,)
For all mount points listed by the previous command, it is necessary to search for files which
do not belong to a valid group using the following command:
$ sudo find MOUNTPOINT -xdev -nogroup 2>/dev/null |
Unowned files do not directly imply a security problem, but they are generally a sign that something is amiss. They may be caused by an intruder, by incorrect software installation or draft software removal, or by failure to remove all files belonging to a deleted account, or other similar cases. The files should be repaired so they will not cause problems when accounts are created in the future, and the cause should be discovered and addressed. |
| CM-6(a) AC-6(1) |
Verify Group Who Owns passwd File |
To properly set the group owner of /etc/passwd, run the command: $ sudo chgrp root /etc/passwd |
The /etc/passwd file contains information about the users that are configured on the system. Protection of this file is critical for system security. |
| CM-6(a) | Enable page allocator poisoning | To enable poisoning of free pages, add the argument page_poison=1 to all BLS (Boot Loader Specification) entries ('options' line) for the Linux operating system in /boot/loader/entries/*.conf. | Poisoning writes an arbitrary value to freed pages, so any modification or reference to that page after being freed or before being initialized will be detected and prevented. This prevents many types of use-after-free vulnerabilities at little performance cost. Also prevents leak of data and detection of corrupted memory. |
| CM-6(a) | Set Boot Loader Password in grub2 |
The grub2 boot loader should have a superuser account and password
protection enabled to protect boot-time settings.
Since plaintext passwords are a security risk, generate a hash for the password by running the following command: # grub2-setpasswordWhen prompted, enter the password that was selected. |
Password protection on the boot loader configuration ensures users with physical access cannot trivially alter important bootloader settings. These include which kernel to use, and whether to enter single-user mode. |
| CM-6(a) AU-8(1)(a) |
Enable the NTP Daemon |
The ntp service can be enabled with the following command:
$ sudo systemctl enable ntp.service |
Enabling the ntp service ensures that the ntp
service will be running and that the system will synchronize its time to
any servers specified. This is important whether the system is configured to be
a client (and synchronize only its own clock) or it is also acting as an NTP
server to other systems. Synchronizing time is essential for authentication
services such as Kerberos, but it is also important for maintaining accurate
logs and auditing possible security breaches.
The NTP daemon offers all of the functionality of ntpdate, which is now deprecated. |
| CM-6(a) | Set the UEFI Boot Loader Admin Username to a Non-Default Value |
The grub2 boot loader should have a superuser account and password
protection enabled to protect boot-time settings.
To maximize the protection, select a password-protected superuser account with unique name, and modify the /etc/grub.d/01_users configuration file to reflect the account name change. It is highly suggested not to use common administrator account names like root, admin, or administrator for the grub2 superuser account. Change the superuser to a different username (The default is 'root'). $ sed -i 's/\(set superusers=\).*/\1"<unique user ID>"/g' /etc/grub.d/01_users Once the superuser account has been added, update the grub.cfg file by running: grubby --update-kernel=ALL --env=/boot/grub2/grubenv |
Having a non-default grub superuser username makes password-guessing attacks less effective. |
| AC-6 (1) | Verify User Who Owns Backup group File |
To properly set the owner of /etc/group-, run the command: $ sudo chown root /etc/group- |
The /etc/group- file is a backup file of /etc/group, and as such, it contains information regarding groups that are configured on the system. Protection of this file is important for system security. |
| CM-6(a) | Install the pcsc-lite package |
The pcsc-lite package can be installed with the following command:
$ sudo yum install pcsc-lite |
The pcsc-lite package must be installed if it is to be available for multifactor authentication using smartcards. |
| CM-6(a) AU-8(1)(a) AU-8(2) |
Specify Additional Remote NTP Servers |
Additional NTP servers can be specified for time synchronization
in the file /etc/ntp.conf. To do so, add additional lines of the
following form, substituting the IP address or hostname of a remote NTP server for
ntpserver:
server ntpserver |
Specifying additional NTP servers increases the availability of accurate time data, in the event that one of the specified servers becomes unavailable. This is typical for a system acting as an NTP server for other systems. |
| CM-6(a) | Install the screen Package |
To enable console screen locking, install the screen package.
The screen package can be installed with the following command:
$ sudo yum install screenInstruct users to begin new terminal sessions with the following command: $ screenThe console can now be locked with the following key combination: ctrl+a x |
A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate
physical vicinity of the information system but does not logout because of the temporary nature of the absence.
Rather than relying on the user to manually lock their operation system session prior to vacating the vicinity,
operating systems need to be able to identify when a user's session has idled and take action to initiate the
session lock.
The screen package allows for a session lock to be implemented and configured. |
| CM-6(a) | Enable logrotate Timer |
The logrotate timer can be enabled with the following command:
$ sudo systemctl enable logrotate.timer |
Log files that are not properly rotated run the risk of growing so large that they fill up the /var/log partition. Valuable logging information could be lost if the /var/log partition becomes full. |
| CM-6(a) AC-6(1) |
Verify /boot/efi/EFI/redhat/user.cfg Group Ownership |
The file /boot/efi/EFI/redhat/user.cfg should be group-owned by the
root group to prevent reading or modification of the file.
To properly set the group owner of /boot/efi/EFI/redhat/user.cfg, run the command:
$ sudo chgrp root /boot/efi/EFI/redhat/user.cfg |
The root group is a highly-privileged group. Furthermore, the group-owner of this file should not have any access privileges anyway. Non-root users who read the boot parameters may be able to identify weaknesses in security upon boot and be able to exploit them. |
| AC-6 CM-6(a) |
Ensure that System Accounts Are Locked |
Some accounts are not associated with a human user of the system, and exist to perform some
administrative functions. An attacker should not be able to log into these accounts.
System accounts are those user accounts with a user ID less than 1000. If any system account other than root, halt, sync, shutdown and nfsnobody has an unlocked password, disable it with the command: $ sudo usermod -L account |
Disabling authentication for default system accounts makes it more difficult for attackers to make use of them to compromise a system. |
| CM-6(a) AC-6(1) CM-6(a) |
Ensure that User Home Directories are not Group-Writable or World-Readable |
For each human user of the system, view the
permissions of the user's home directory:
# ls -ld /home/USEREnsure that the directory is not group-writable and that it is not world-readable. If necessary, repair the permissions: # chmod g-w /home/USER # chmod o-rwx /home/USER |
User home directories contain many configuration files which affect the behavior of a user's account. No user should ever have write permission to another user's home directory. Group shared directories can be configured in sub-directories or elsewhere in the filesystem if they are needed. Typically, user home directories should not be world-readable, as it would disclose file names to other users. If a subset of users need read access to one another's home directories, this can be provided using groups or ACLs. |
| CM-6(a) AC-6(1) AU-9(4) |
System Audit Logs Must Be Owned By Root |
All audit logs must be owned by root user and group. By default, the path for audit log is /var/log/audit/. To properly set the owner of /var/log/audit, run the command:
$ sudo chown root /var/log/auditTo properly set the owner of /var/log/audit/*, run the command:
$ sudo chown root /var/log/audit/* |
Unauthorized disclosure of audit records can reveal system and configuration data to attackers, thus compromising its confidentiality. |
| CM-6(a) AC-6(1) |
Verify that All World-Writable Directories Have Sticky Bits Set |
When the so-called 'sticky bit' is set on a directory, only the owner of a given file may
remove that file from the directory. Without the sticky bit, any user with write access to a
directory may remove any file in the directory. Setting the sticky bit prevents users from
removing each other's files. In cases where there is no reason for a directory to be
world-writable, a better solution is to remove that permission rather than to set the sticky
bit. However, if a directory is used by a particular application, consult that application's
documentation instead of blindly changing modes.
To set the sticky bit on a world-writable directory DIR, run the following command: $ sudo chmod +t DIR |
Failing to set the sticky bit on public directories allows unauthorized users to delete files
in the directory structure.
The only authorized public directories are those temporary directories supplied with the system, or those designed to be temporary file repositories. The setting is normally reserved for directories used by the system, by users for temporary file storage (such as /tmp), and for directories requiring global read/write access. |
| CM-6 SC-7(10) |
Harden the operation of the BPF just-in-time compiler |
To set the runtime status of the net.core.bpf_jit_harden kernel parameter, run the following command: $ sudo sysctl -w net.core.bpf_jit_harden=2To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.core.bpf_jit_harden = 2 |
When hardened, the extended Berkeley Packet Filter just-in-time compiler will randomize any kernel addresses in the BPF programs and maps, and will not expose the JIT addresses in /proc/kallsyms. |
| CM-6(a) AU-4(1) AU-9(2) |
Ensure Logs Sent To Remote Host |
To configure rsyslog to send logs to a remote log server,
open /etc/rsyslog.conf and read and understand the last section of the file,
which describes the multiple directives necessary to activate remote
logging.
Along with these other directives, the system can be configured
to forward its logs to a particular log server by
adding or correcting one of the following lines,
substituting logcollector appropriately.
The choice of protocol depends on the environment of the system;
although TCP and RELP provide more reliable message delivery,
they may not be supported in all environments.
To use UDP for log message delivery: *.* @logcollector To use TCP for log message delivery: *.* @@logcollector To use RELP for log message delivery: *.* :omrelp:logcollector There must be a resolvable DNS CNAME or Alias record set to "logcollector" for logs to be sent correctly to the centralized logging utility. |
A log server (loghost) receives syslog messages from one or more systems. This data can be used as an additional log source in the event a system is compromised and its local logs are suspect. Forwarding log messages to a remote loghost also provides system administrators with a centralized place to view the status of multiple hosts within the enterprise. |
| CM-6(a) AU-4(1) |
Enable rsyslog Service |
The rsyslog service provides syslog-style logging by default on Red Hat Enterprise Linux 8.
The rsyslog service can be enabled with the following command:
$ sudo systemctl enable rsyslog.service |
The rsyslog service must be running in order to provide logging services, which are essential to system administration. |
| CM-6(a) AC-6(1) |
Verify /boot/grub2/user.cfg User Ownership |
The file /boot/grub2/user.cfg should be owned by the root
user to prevent reading or modification of the file.
To properly set the owner of /boot/grub2/user.cfg, run the command:
$ sudo chown root /boot/grub2/user.cfg |
Only root should be able to modify important boot parameters. Also, non-root users who read the boot parameters may be able to identify weaknesses in security upon boot and be able to exploit them. |
| CM-6(b) CM-6.1(iv) |
Add nosuid Option to /boot/efi |
The nosuid mount option can be used to prevent
execution of setuid programs in /boot/efi. The SUID and SGID permissions
should not be required on the boot partition.
Add the nosuid option to the fourth column of
/etc/fstab for the line which controls mounting of
/boot/efi.
|
The presence of SUID and SGID executables should be tightly controlled. Users should not be able to execute SUID or SGID binaries from boot partitions. |
| CM-6(b) | Add noexec Option to /home |
The noexec mount option can be used to prevent binaries from being
executed out of /home.
Add the noexec option to the fourth column of
/etc/fstab for the line which controls mounting of
/home.
|
The /home directory contains data of individual users. Binaries in this directory should not be considered as trusted and users should not be able to execute them. |
| CM-6(a) AC-6(1) |
Verify Group Who Owns shadow File |
To properly set the group owner of /etc/shadow, run the command: $ sudo chgrp root /etc/shadow |
The /etc/shadow file stores password hashes. Protection of this file is critical for system security. |
| CM-6(a) AC-6(1) |
Verify Permissions on group File |
To properly set the permissions of /etc/group, run the command:
$ sudo chmod 0644 /etc/group |
The /etc/group file contains information regarding groups that are configured on the system. Protection of this file is important for system security. |
| CM-6(b) CM-6.1(iv) |
Ensure There Are No Accounts With Blank or Null Passwords |
Check the "/etc/shadow" file for blank passwords with the
following command:
$ sudo awk -F: '!$2 {print $1}' /etc/shadow
If the command returns any results, this is a finding.
Configure all accounts on the system to have a password or lock
the account with the following commands:
Perform a password reset:
$ sudo passwd [username]Lock an account: $ sudo passwd -l [username] |
If an account has an empty password, anyone could log in and run commands with the privileges of that account. Accounts with empty passwords should never be used in operational environments. |
| CM-6(a) AC-11(a) |
Enable GNOME3 Screensaver Idle Activation |
To activate the screensaver in the GNOME3 desktop after a period of inactivity,
add or set idle-activation-enabled to true in
/etc/dconf/db/local.d/00-security-settings. For example:
[org/gnome/desktop/screensaver] idle-activation-enabled=trueOnce the setting has been added, add a lock to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification. For example: /org/gnome/desktop/screensaver/idle-activation-enabledAfter the settings have been set, run dconf update. |
A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate
physical vicinity of the information system but does not logout because of the temporary nature of the absence.
Rather than relying on the user to manually lock their operating system session prior to vacating the vicinity,
GNOME desktops can be configured to identify when a user's session has idled and take action to initiate the
session lock.
Enabling idle activation of the screensaver ensures the screensaver will be activated after the idle delay. Applications requiring continuous, real-time screen display (such as network management products) require the login session does not have administrator rights and the display station is located in a controlled-access area. |
| CM-6(a) | Install PAE Kernel on Supported 32-bit x86 Systems |
Systems that are using the 64-bit x86 kernel package
do not need to install the kernel-PAE package because the 64-bit
x86 kernel already includes this support. However, if the system is
32-bit and also supports the PAE and NX features as
determined in the previous section, the kernel-PAE package should
be installed to enable XD or NX support.
The kernel-PAE package can be installed with the following command:
$ sudo yum install kernel-PAEThe installation process should also have configured the bootloader to load the new kernel at boot. Verify this after reboot and modify /etc/default/grub if necessary. |
On 32-bit systems that support the XD or NX bit, the vendor-supplied PAE kernel is required to enable either Execute Disable (XD) or No Execute (NX) support. |
| CM-6(a) AU-4 SC-5(2) |
Ensure /var/log Located On Separate Partition |
System logs are stored in the /var/log directory.
Ensure that /var/log has its own partition or logical
volume at installation time, or migrate it using LVM.
|
Placing /var/log in its own partition enables better separation between log files and other files in /var/. |
| CM-6(a) AC-6(1) CM-7(b) |
Disable the GNOME3 Login Restart and Shutdown Buttons |
In the default graphical environment, users logging directly into the
system are greeted with a login screen that allows any user, known or
unknown, the ability the ability to shutdown or restart the system. This
functionality should be disabled by setting
disable-restart-buttons to true.
To disable, add or edit disable-restart-buttons to /etc/dconf/db/gdm.d/00-security-settings. For example: [org/gnome/login-screen] disable-restart-buttons=trueOnce the setting has been added, add a lock to /etc/dconf/db/gdm.d/locks/00-security-settings-lock to prevent user modification. For example: /org/gnome/login-screen/disable-restart-buttonsAfter the settings have been set, run dconf update. |
A user who is at the console can reboot the system at the login screen. If restart or shutdown buttons are pressed at the login screen, this can create the risk of short-term loss of availability of systems due to reboot. |
| CM-6(a) | Build and Test AIDE Database |
Run the following command to generate a new database:
$ sudo /usr/sbin/aide --initBy default, the database will be written to the file /var/lib/aide/aide.db.new.gz. Storing the database, the configuration file /etc/aide.conf, and the binary /usr/sbin/aide (or hashes of these files), in a secure location (such as on read-only media) provides additional assurance about their integrity. The newly-generated database can be installed as follows: $ sudo cp /var/lib/aide/aide.db.new.gz /var/lib/aide/aide.db.gzTo initiate a manual check, run the following command: $ sudo /usr/sbin/aide --checkIf this check produces any unexpected output, investigate. |
For AIDE to be effective, an initial database of "known-good" information about files must be captured and it should be able to be verified against the installed files. |
| CM-6(a) | Ensure Users Cannot Change GNOME3 Screensaver Lock After Idle Period |
If not already configured, ensure that users cannot change GNOME3 screensaver lock settings
by adding /org/gnome/desktop/screensaver/lock-enabledto /etc/dconf/db/local.d/locks/00-security-settings. For example: /org/gnome/desktop/screensaver/lock-enabledAfter the settings have been set, run dconf update. |
A session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not want to logout because of the temporary nature of the absense. |
| AC-6 SC-7(10) |
Disable Access to Network bpf() Syscall From Unprivileged Processes |
To prevent unprivileged processes from using the bpf() syscall
the kernel.unprivileged_bpf_disabled kernel parameter must
be set to 1 or 2.
Writing 1 to this entry will disable unprivileged calls to bpf(); once
disabled, calling bpf() without CAP_SYS_ADMIN or CAP_BPF will return -EPERM.
Once set to 1, this can't be cleared from the running kernel anymore.
To set the runtime status of the kernel.unprivileged_bpf_disabled kernel parameter,
run the following command:
$ sudo sysctl -w kernel.unprivileged_bpf_disabled=1To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: kernel.unprivileged_bpf_disabled = 1Writing 2 to this entry will also disable unprivileged calls to bpf(),
however, an admin can still change this setting later on, if needed, by
writing 0 or 1 to this entry.
To set the runtime status of the kernel.unprivileged_bpf_disabled kernel parameter,
run the following command:
$ sudo sysctl -w kernel.unprivileged_bpf_disabled=2To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: kernel.unprivileged_bpf_disabled = 2 |
Loading and accessing the packet filters programs and maps using the bpf() syscall has the potential of revealing sensitive information about the kernel state. |
| CM-6(a) AC-6(1) AU-9(4) |
System Audit Directories Must Be Owned By Root |
All audit directories must be owned by root user. By default, the path for audit log is /var/log/audit/. To properly set the owner of /var/log/audit, run the command:
$ sudo chown root /var/log/audit |
Unauthorized disclosure of audit records can reveal system and configuration data to attackers, thus compromising its confidentiality. |
| CM-6(a) AC-6(1) |
Disable Ctrl-Alt-Del Reboot Activation |
By default, SystemD will reboot the system if the Ctrl-Alt-Del
key sequence is pressed.
To configure the system to ignore the Ctrl-Alt-Del key sequence from the command line instead of rebooting the system, do either of the following: ln -sf /dev/null /etc/systemd/system/ctrl-alt-del.targetor systemctl mask ctrl-alt-del.target Do not simply delete the /usr/lib/systemd/system/ctrl-alt-del.service file, as this file may be restored during future system updates. |
A locally logged-in user who presses Ctrl-Alt-Del, when at the console, can reboot the system. If accidentally pressed, as could happen in the case of mixed OS environment, this can create the risk of short-term loss of availability of systems due to unintentional reboot. |
| CM-6(a) SC-28 SI-3(a) |
Install McAfee Virus Scanning Software | Install McAfee VirusScan Enterprise for Linux antivirus software which is provided for DoD systems and uses signatures to search for the presence of viruses on the filesystem. | Virus scanning software can be used to detect if a system has been compromised by computer viruses, as well as to limit their spread to other systems. |
| CM-6(a) AC-6(1) |
Ensure No World-Writable Files Exist | It is generally a good idea to remove global (other) write access to a file when it is discovered. However, check with documentation for specific applications before making changes. Also, monitor for recurring world-writable files, as these may be symptoms of a misconfigured application or user account. Finally, this applies to real files and not virtual files that are a part of pseudo file systems such as sysfs or procfs. | Data in world-writable files can be modified by any user on the system. In almost all circumstances, files can be configured using a combination of user and group permissions to support whatever legitimate access is needed without the risk caused by world-writable files. |
| CM-6(a) | Ensure logrotate is Installed |
logrotate is installed by default. The logrotate package can be installed with the following command: $ sudo yum install logrotate |
The logrotate package provides the logrotate services. |
| CM-6(a) | Install AIDE |
The aide package can be installed with the following command:
$ sudo yum install aide |
The AIDE package must be installed if it is to be available for integrity checking. |
| CM-6(a) | Ensure Users Cannot Change GNOME3 Session Idle Settings |
If not already configured, ensure that users cannot change GNOME3 session idle settings
by adding /org/gnome/desktop/session/idle-delay
to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification.
For example:
/org/gnome/desktop/session/idle-delayAfter the settings have been set, run dconf update. |
A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not logout because of the temporary nature of the absence. Rather than relying on the user to manually lock their operating system session prior to vacating the vicinity, GNOME desktops can be configured to identify when a user's session has idled and take action to initiate the session lock. As such, users should not be allowed to change session settings. |
| CM-6(a) | Extend Audit Backlog Limit for the Audit Daemon | To improve the kernel capacity to queue all log events, even those which occurred prior to the audit daemon, add the argument audit_backlog_limit=8192 to all BLS (Boot Loader Specification) entries ('options' line) for the Linux operating system in /boot/loader/entries/*.conf. | audit_backlog_limit sets the queue length for audit events awaiting transfer to the audit daemon. Until the audit daemon is up and running, all log messages are stored in this queue. If the queue is overrun during boot process, the action defined by audit failure flag is taken. |
| CM-6(a) AC-6(1) AU-9(4) |
System Audit Logs Must Be Group Owned By Root |
All audit logs must be group owned by root user. The path for audit log can
be configured via log_file parameter in /etc/audit/auditd.confor, by default, the path for audit log is /var/log/audit/. To properly set the group owner of /var/log/audit/*, run the command:
$ sudo chgrp root /var/log/audit/*If log_group in /etc/audit/auditd.conf is set to a group other than the root group account, change the group ownership of the audit logs to this specific group. |
Unauthorized disclosure of audit records can reveal system and configuration data to attackers, thus compromising its confidentiality. |
| CM-6(b) | Prevent remote hosts from connecting to the proxy display |
The SSH daemon should prevent remote hosts from connecting to the proxy
display.
The default SSH configuration for X11UseLocalhost is yes, which prevents remote hosts from connecting to the proxy display. To explicitly prevent remote connections to the proxy display, add or correct the following line in /etc/ssh/sshd_config: X11UseLocalhost yes |
When X11 forwarding is enabled, there may be additional exposure to the server and client displays if the sshd proxy display is configured to listen on the wildcard address. By default, sshd binds the forwarding server to the loopback address and sets the hostname part of the DISPLAY environment variable to localhost. This prevents remote hosts from connecting to the proxy display. |
| CM-6(a) AC-6(1) |
Ensure Log Files Are Owned By Appropriate Group |
The group-owner of all log files written by
rsyslog should be root.
These log files are determined by the second part of each Rule line in
/etc/rsyslog.conf and typically all appear in /var/log.
For each log file LOGFILE referenced in /etc/rsyslog.conf,
run the following command to inspect the file's group owner:
$ ls -l LOGFILEIf the owner is not root, run the following command to correct this: $ sudo chgrp root LOGFILE |
The log files generated by rsyslog contain valuable information regarding system configuration, user authentication, and other such information. Log files should be protected from unauthorized access. |
| CM-6(a) AC-6(1) |
Verify Owner on cron.weekly |
To properly set the owner of /etc/cron.weekly, run the command:
$ sudo chown root /etc/cron.weekly |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct user to prevent unauthorized changes. |
| CM-6(a) AC-6(1) |
Ensure All SUID Executables Are Authorized | The SUID (set user id) bit should be set only on files that were installed via authorized means. A straightforward means of identifying unauthorized SUID files is determine if any were not installed as part of an RPM package, which is cryptographically verified. Investigate the origin of any unpackaged SUID files. This configuration check considers authorized SUID files those which were installed via RPM. It is assumed that when an individual has sudo access to install an RPM and all packages are signed with an organizationally-recognized GPG key, the software should be considered an approved package on the system. Any SUID file not deployed through an RPM will be flagged for further review. | Executable files with the SUID permission run with the privileges of the owner of the file. SUID files of uncertain provenance could allow for unprivileged users to elevate privileges. The presence of these files should be strictly controlled on the system. |
| CM-6(a) AU-4 SC-5(2) |
Ensure /var/log/audit Located On Separate Partition |
Audit logs are stored in the /var/log/audit directory.
Ensure that /var/log/audit has its own partition or logical
volume at installation time, or migrate it using LVM.
Make absolutely certain that it is large enough to store all
audit logs that will be created by the auditing daemon.
|
Placing /var/log/audit in its own partition enables better separation between audit files and other files, and helps ensure that auditing cannot be halted due to the partition running out of space. |
| CM-6(a) MA-6 SA-13(a) |
The Installed Operating System Is Vendor Supported | The installed operating system must be maintained by a vendor. Red Hat Enterprise Linux is supported by Red Hat, Inc. As the Red Hat Enterprise Linux vendor, Red Hat, Inc. is responsible for providing security patches. | An operating system is considered "supported" if the vendor continues to provide security patches for the product. With an unsupported release, it will not be possible to resolve any security issue discovered in the system software. |
| CM-6(a) AC-6(1) |
Verify Group Who Owns Crontab |
To properly set the group owner of /etc/crontab, run the command:
$ sudo chgrp root /etc/crontab |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct group to prevent unauthorized changes. |
| CM-6(a) SI-4(22) |
Install fapolicyd Package |
The fapolicyd package can be installed with the following command:
$ sudo yum install fapolicyd |
fapolicyd (File Access Policy Daemon) implements application whitelisting to decide file access rights. |
| CM-6(a) AC-6(1) |
Verify Group Who Owns cron.weekly |
To properly set the group owner of /etc/cron.weekly, run the command:
$ sudo chgrp root /etc/cron.weekly |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct group to prevent unauthorized changes. |
| CM-6(a) | Install Smart Card Packages For Multifactor Authentication |
Configure the operating system to implement multifactor authentication by
installing the required package with the following command:
The openssl-pkcs11 package can be installed with the following command:
$ sudo yum install openssl-pkcs11 |
Using an authentication device, such as a CAC or token that is separate from
the information system, ensures that even if the information system is
compromised, that compromise will not affect credentials stored on the
authentication device.
Multifactor solutions that require devices separate from information systems gaining access include, for example, hardware tokens providing time-based or challenge-response authenticators and smart cards such as the U.S. Government Personal Identity Verification card and the DoD Common Access Card. |
| CM-6(a) IA-5(13) |
Configure SSSD to Expire Offline Credentials |
SSSD should be configured to expire offline credentials after 1 day.
Check if SSSD allows cached authentications with the following command:
$ sudo grep cache_credentials /etc/sssd/sssd.conf cache_credentials = trueIf "cache_credentials" is set to "false" or is missing no further checks are required. To configure SSSD to expire offline credentials, set offline_credentials_expiration to 1 under the [pam] section in /etc/sssd/sssd.conf. For example: [pam] offline_credentials_expiration = 1 |
If cached authentication information is out-of-date, the validity of the authentication information may be questionable. |
| CM-6(a) AC-6(1) |
Verify Permissions on gshadow File |
To properly set the permissions of /etc/gshadow, run the command:
$ sudo chmod 0000 /etc/gshadow |
The /etc/gshadow file contains group password hashes. Protection of this file is critical for system security. |
| CM-6 AU-3 |
Resolve information before writing to audit logs | To configure Audit daemon to resolve all uid, gid, syscall, architecture, and socket address information before writing the events to disk, set log_format to ENRICHED in /etc/audit/auditd.conf. | If option log_format isn't set to ENRICHED, the audit records will be stored in a format exactly as the kernel sends them. |
| CM-6(a) AC-6(1) |
Verify Permissions on cron.hourly |
To properly set the permissions of /etc/cron.hourly, run the command:
$ sudo chmod 0700 /etc/cron.hourly |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should have the correct access rights to prevent unauthorized changes. |
| CM-6(b) | Add grpquota Option to /home |
The grpquota mount option allows for the filesystem to have disk quotas configured.
Add the grpquota option to the fourth column of
/etc/fstab for the line which controls mounting of
/home.
|
To ensure the availability of disk space on /home, it is important to limit the impact a single user or group can cause for other users (or the wider system) by intentionally or accidentally filling up the partition. Quotas can also be applied to inodes for filesystems where inode exhaustion is a concern. |
| CM-6(a) MA-4(6) SC-13 SC-12(2) SC-12(3) |
Configure Libreswan to use System Crypto Policy | Crypto Policies provide a centralized control over crypto algorithms usage of many packages. Libreswan is supported by system crypto policy, but the Libreswan configuration may be set up to ignore it. To check that Crypto Policies settings are configured correctly, ensure that the /etc/ipsec.conf includes the appropriate configuration file. In /etc/ipsec.conf, make sure that the following line is not commented out or superseded by later includes: include /etc/crypto-policies/back-ends/libreswan.config | Overriding the system crypto policy makes the behavior of the Libreswan service violate expectations, and makes system configuration more fragmented. |
| CM-6(a) CM-3(5) |
Configure Notification of Post-AIDE Scan Details |
AIDE should notify appropriate personnel of the details of a scan after the scan has been run.
If AIDE has already been configured for periodic execution in /etc/crontab, append the
following line to the existing AIDE line:
| /bin/mail -s "$(hostname) - AIDE Integrity Check" root@localhostOtherwise, add the following line to /etc/crontab: 05 4 * * * root /usr/sbin/aide --check | /bin/mail -s "$(hostname) - AIDE Integrity Check" root@localhostAIDE can be executed periodically through other means; this is merely one example. |
Unauthorized changes to the baseline configuration could make the system vulnerable
to various attacks or allow unauthorized access to the operating system. Changes to
operating system configurations can have unintended side effects, some of which may
be relevant to security.
Detecting such changes and providing an automated response can help avoid unintended, negative consequences that could ultimately affect the security state of the operating system. The operating system's Information Management Officer (IMO)/Information System Security Officer (ISSO) and System Administrators (SAs) must be notified via email and/or monitoring system trap when there is an unauthorized modification of a configuration item. |
| AC-6 (1) | Verify Group Who Owns Backup gshadow File |
To properly set the group owner of /etc/gshadow-, run the command: $ sudo chgrp root /etc/gshadow- |
The /etc/gshadow- file is a backup of /etc/gshadow, and as such, it contains group password hashes. Protection of this file is critical for system security. |
| AC-6(1) CM-6(a) |
Ensure the Default C Shell Umask is Set Correctly |
To ensure the default umask for users of the C shell is set properly,
add or correct the umask setting in /etc/csh.cshrc to read as follows:
umask 027 |
The umask value influences the permissions assigned to files when they are created. A misconfigured umask value could result in files with excessive permissions that can be read or written to by unauthorized users. |
| AC-6(1) CM-6(a) |
Ensure the Default Umask is Set Correctly in login.defs |
To ensure the default umask controlled by /etc/login.defs is set properly,
add or correct the UMASK setting in /etc/login.defs to read as follows:
UMASK 027 |
The umask value influences the permissions assigned to files when they are created. A misconfigured umask value could result in files with excessive permissions that can be read and written to by unauthorized users. |
| AC-6(1) CM-6(a) |
Ensure the Default Umask is Set Correctly in /etc/profile |
To ensure the default umask controlled by /etc/profile is set properly,
add or correct the umask setting in /etc/profile to read as follows:
umask 027Note that /etc/profile also reads scrips within /etc/profile.d directory. These scripts are also valid files to set umask value. Therefore, they should also be considered during the check and properly remediated, if necessary. |
The umask value influences the permissions assigned to files when they are created. A misconfigured umask value could result in files with excessive permissions that can be read or written to by unauthorized users. |
| AC-6(1) CM-6(a) |
Ensure the Default Bash Umask is Set Correctly |
To ensure the default umask for users of the Bash shell is set properly,
add or correct the umask setting in /etc/bashrc to read
as follows:
umask 027 |
The umask value influences the permissions assigned to files when they are created. A misconfigured umask value could result in files with excessive permissions that can be read or written to by unauthorized users. |
| AC-6(2) AC-17(a) IA-2 IA-2(5) CM-7(a) CM-7(b) CM-6(a) |
Disable SSH Root Login |
The root user should never be allowed to login to a
system directly over a network.
To disable root login via SSH, add or correct the following line in
/etc/ssh/sshd_config:
PermitRootLogin no |
Even though the communications channel may be encrypted, an additional layer of security is gained by extending the policy of not logging directly on as root. In addition, logging in with a user-specific account provides individual accountability of actions performed on the system and also helps to minimize direct attack attempts on root's password. |
| AC-6(9) CM-6(a) |
Make the auditd Configuration Immutable |
If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following line to a file with suffix .rules in the
directory /etc/audit/rules.d in order to make the auditd configuration
immutable:
-e 2If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file in order to make the auditd configuration immutable: -e 2With this setting, a reboot will be required to change any audit rules. |
Making the audit configuration immutable prevents accidental as well as malicious modification of the audit rules, although it may be problematic if legitimate changes are needed during system operation. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Mounting of hfsplus |
To configure the system to prevent the hfsplus
kernel module from being loaded, add the following line to the file /etc/modprobe.d/hfsplus.conf:
install hfsplus /bin/falseTo configure the system to prevent the hfsplus from being used,
add the following line to file /etc/modprobe.d/hfsplus.conf:
blacklist hfsplusThis effectively prevents usage of this uncommon filesystem. |
Linux kernel modules which implement filesystems that are not needed by the local system should be disabled. |
| SI-7 SI-7(1) CM-6(a) |
Configure AIDE to Verify Access Control Lists (ACLs) |
By default, the acl option is added to the FIPSR ruleset in AIDE.
If using a custom ruleset or the acl option is missing, add acl
to the appropriate ruleset.
For example, add acl to the following line in /etc/aide.conf:
FIPSR = p+i+n+u+g+s+m+c+acl+selinux+xattrs+sha256AIDE rules can be configured in multiple ways; this is merely one example that is already configured by default. The remediation provided with this rule adds acl to all rule sets available in /etc/aide.conf |
ACLs can provide permissions beyond those permitted through the file mode and must be verified by the file integrity tools. |
| CM-7(a) CM-7(b) CM-6(a) SC-7(a) |
Enable Kernel Parameter to Use Reverse Path Filtering on all IPv4 Interfaces by Default |
To set the runtime status of the net.ipv4.conf.default.rp_filter kernel parameter, run the following command: $ sudo sysctl -w net.ipv4.conf.default.rp_filter=1To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv4.conf.default.rp_filter = 1 |
Enabling reverse path filtering drops packets with source addresses that should not have been able to be received on the interface they were received on. It should not be used on systems which are routers for complicated networks, but is helpful for end hosts and routers serving small networks. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Quota Netlink (quota_nld) |
The quota_nld service provides notifications to
users of disk space quota violations. It listens to the kernel via a netlink
socket for disk quota violations and notifies the appropriate user of the
violation using D-Bus or by sending a message to the terminal that the user has
last accessed.
The quota_nld service can be disabled with the following command:
$ sudo systemctl mask --now quota_nld.service |
If disk quotas are enforced on the local system, then the quota_nld service likely provides useful functionality and should remain enabled. However, if disk quotas are not used or user notification of disk quota violation is not desired then there is no need to run this service. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Cyrus SASL Authentication Daemon (saslauthd) |
The saslauthd service handles plaintext authentication requests on
behalf of the SASL library. The service isolates all code requiring superuser
privileges for SASL authentication into a single process, and can also be used
to provide proxy authentication services to clients that do not understand SASL
based authentication.
The saslauthd service can be disabled with the following command:
$ sudo systemctl mask --now saslauthd.service |
The saslauthd service provides essential functionality for performing authentication in some directory environments, such as those which use Kerberos and LDAP. For others, however, in which only local files may be consulted, it is not necessary and should be disabled. |
| CM-7(a) CM-7(b) SC-5 CM-6(a) SC-7(a) |
Disable Kernel Parameter for IP Forwarding on IPv4 Interfaces |
To set the runtime status of the net.ipv4.ip_forward kernel parameter, run the following command: $ sudo sysctl -w net.ipv4.ip_forward=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv4.ip_forward = 0 |
Routing protocol daemons are typically used on routers to exchange network topology information with other routers. If this capability is used when not required, system network information may be unnecessarily transmitted across the network. |
| AC-7 (ia) | Account Lockouts Must Persist | By setting a `dir` in the faillock configuration account lockouts will persist across reboots. | Having lockouts persist across reboots ensures that account is only unlocked by an administrator. If the lockouts did not persist across reboots an attack could simply reboot the system to continue brute force attacks against the accounts on the system. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable xinetd Service |
The xinetd service can be disabled with the following command:
$ sudo systemctl mask --now xinetd.service |
The xinetd service provides a dedicated listener service for some programs, which is no longer necessary for commonly-used network services. Disabling it ensures that these uncommon services are not running, and also prevents attacks against xinetd itself. |
| CM-7(a) CM-7(b) CM-6(a) AC-17(a) |
Disable GSSAPI Authentication |
Unless needed, SSH should not permit extraneous or unnecessary
authentication mechanisms like GSSAPI.
The default SSH configuration disallows authentications based on GSSAPI. The appropriate configuration is used if no value is set for GSSAPIAuthentication. To explicitly disable GSSAPI authentication, add or correct the following line in /etc/ssh/sshd_config: GSSAPIAuthentication no |
GSSAPI authentication is used to provide additional authentication mechanisms to applications. Allowing GSSAPI authentication through SSH exposes the system's GSSAPI to remote hosts, increasing the attack surface of the system. |
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall avahi Server Package | If the system does not need to have an Avahi server which implements the DNS Service Discovery and Multicast DNS protocols, the avahi-autoipd and avahi packages can be uninstalled. | Automatic discovery of network services is not normally required for system functionality. It is recommended to remove this package to reduce the potential attack surface. |
| CM-7(a) CM-7(b) CM-6(a) |
Restrict NFS Clients to Privileged Ports |
By default, the server NFS implementation requires that all client requests be made
from ports less than 1024. If your organization has control over systems connected to its
network, and if NFS requests are prohibited at the border firewall, this offers some protection
against malicious requests from unprivileged users. Therefore, the default should not be changed.
To ensure that the default has not been changed, ensure no line in /etc/exports contains the option insecure. |
Allowing client requests to be made from ports higher than 1024 could allow a unprivileged user to initiate an NFS connection. If the unprivileged user account has been compromised, an attacker could gain access to data on the NFS server. |
| AC-7 (a) | Configure the Use of the pam_faillock.so Module in the /etc/pam.d/system-auth File. | The pam_faillock.so module must be loaded in preauth in /etc/pam.d/system-auth. | If the pam_faillock.so module is not loaded the system will not correctly lockout accounts to prevent password guessing attacks. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add nosuid Option to /dev/shm |
The nosuid mount option can be used to prevent execution
of setuid programs in /dev/shm. The SUID and SGID permissions should not
be required in these world-writable directories.
Add the nosuid option to the fourth column of
/etc/fstab for the line which controls mounting of
/dev/shm.
|
The presence of SUID and SGID executables should be tightly controlled. Users should not be able to execute SUID or SGID binaries from temporary storage partitions. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable IPv6 Addressing on IPv6 Interfaces by Default |
To disable support for (ipv6) addressing on interfaces by default add the following line to
/etc/sysctl.d/ipv6.conf (or another file in /etc/sysctl.d):
net.ipv6.conf.default.disable_ipv6 = 1This disables IPv6 on network interfaces by default as other services and system functionality require the IPv6 stack loaded to work. |
Any unnecessary network stacks - including IPv6 - should be disabled, to reduce the vulnerability to exploitation. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add nosuid Option to /boot |
The nosuid mount option can be used to prevent
execution of setuid programs in /boot. The SUID and SGID permissions
should not be required on the boot partition.
Add the nosuid option to the fourth column of
/etc/fstab for the line which controls mounting of
/boot.
|
The presence of SUID and SGID executables should be tightly controlled. Users should not be able to execute SUID or SGID binaries from boot partitions. |
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall xinetd Package |
The xinetd package can be removed with the following command:
$ sudo yum erase xinetd |
Removing the xinetd package decreases the risk of the xinetd service's accidental (or intentional) activation. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add nosuid Option to Removable Media Partitions |
The nosuid mount option prevents set-user-identifier (SUID)
and set-group-identifier (SGID) permissions from taking effect. These permissions
allow users to execute binaries with the same permissions as the owner and group
of the file respectively. Users should not be allowed to introduce SUID and SGID
files into the system via partitions mounted from removeable media.
Add the nosuid option to the fourth column of
/etc/fstab for the line which controls mounting of
any removable media partitions.
|
The presence of SUID and SGID executables should be tightly controlled. Allowing users to introduce SUID or SGID binaries from partitions mounted off of removable media would allow them to introduce their own highly-privileged programs. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Red Hat Network Service (rhnsd) |
The Red Hat Network service automatically queries Red Hat Network
servers to determine whether there are any actions that should be executed,
such as package updates. This only occurs if the system was registered to an
RHN server or satellite and managed as such.
The rhnsd service can be disabled with the following command:
$ sudo systemctl mask --now rhnsd.service |
Although systems management and patching is extremely important to system security, management by a system outside the enterprise enclave is not desirable for some environments. However, if the system is being managed by RHN or RHN Satellite Server the rhnsd daemon can remain on. |
| MP-7 CM-6(a) |
Disable Kernel Support for USB via Bootloader Configuration |
All USB support can be disabled by adding the nousb
argument to the kernel's boot loader configuration. To do so,
append "nousb" to the kernel line in /etc/default/grub as shown:
kernel /vmlinuz-VERSION ro vga=ext root=/dev/VolGroup00/LogVol00 rhgb quiet nousb |
Disabling the USB subsystem within the Linux kernel at system boot will protect against potentially malicious USB devices, although it is only practical in specialized systems. |
| CM-7(a) CM-7(b) CM-6(a) AC-6(1) |
Set Permissions on All Configuration Files Inside /etc/httpd/conf.d/ |
To properly set the permissions of /etc/http/conf.d/*, run the command: $ sudo chmod 0640 /etc/http/conf.d/* |
Access to the web server's configuration files may allow an unauthorized user or attacker to access information about the web server or to alter the server's configuration files. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable CPU Speed (cpupower) |
The cpupower service can adjust the clock speed of supported CPUs based upon
the current processing load thereby conserving power and reducing heat.
The cpupower service can be disabled with the following command:
$ sudo systemctl mask --now cpupower.service |
The cpupower service is only necessary if adjusting the CPU clock speed provides benefit. Traditionally this has included laptops (to enhance battery life), but may also apply to server or desktop environments where conserving power is highly desirable or necessary. |
| SI-7 SI-7(1) CM-6(a) |
Configure Periodic Execution of AIDE |
At a minimum, AIDE should be configured to run a weekly scan.
To implement a daily execution of AIDE at 4:05am using cron, add the following line to /etc/crontab:
05 4 * * * root /usr/sbin/aide --checkTo implement a weekly execution of AIDE at 4:05am using cron, add the following line to /etc/crontab: 05 4 * * 0 root /usr/sbin/aide --checkAIDE can be executed periodically through other means; this is merely one example. The usage of cron's special time codes, such as @daily and @weekly is acceptable. |
By default, AIDE does not install itself for periodic execution. Periodically
running AIDE is necessary to reveal unexpected changes in installed files.
Unauthorized changes to the baseline configuration could make the system vulnerable to various attacks or allow unauthorized access to the operating system. Changes to operating system configurations can have unintended side effects, some of which may be relevant to security. Detecting such changes and providing an automated response can help avoid unintended, negative consequences that could ultimately affect the security state of the operating system. The operating system's Information Management Officer (IMO)/Information System Security Officer (ISSO) and System Administrators (SAs) must be notified via email and/or monitoring system trap when there is an unauthorized modification of a configuration item. |
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall 389-ds-base Package | The 389-ds-base RPM is not installed by default on a Red Hat Enterprise Linux 8 system. It is needed only by the 389-ds server, not by the clients which use LDAP for authentication. If the system is not intended for use as an LDAP Server it should be removed. | Unnecessary packages should not be installed to decrease the attack surface of the system. While this software is clearly essential on an LDAP server, it is not necessary on typical desktop or workstation systems. |
| AC-7(b) AC-7(a) AC-7.1(ii) |
Lock Accounts Must Persist |
This rule ensures that the system lock out accounts using pam_faillock.so persist
after system reboot. From "pam_faillock" man pages:
Note that the default directory that "pam_faillock" uses is usually cleared on system boot so the access will be reenabled after system reboot. If that is undesirable, a different tally directory must be set with the "dir" option.pam_faillock.so module requires multiple entries in pam files. These entries must be carefully defined to work as expected. In order to avoid errors when manually editing these files, it is recommended to use the appropriate tools, such as authselect or authconfig, depending on the OS version. The chosen profile expects the directory to be /var/log/faillock. |
Locking out user accounts after a number of incorrect attempts prevents direct password guessing attacks. In combination with the silent option, user enumeration attacks are also mitigated. |
| CM-7(a) CM-7(b) SC-5 |
Enable Kernel Parameter to Ignore ICMP Broadcast Echo Requests on IPv4 Interfaces |
To set the runtime status of the net.ipv4.icmp_echo_ignore_broadcasts kernel parameter, run the following command: $ sudo sysctl -w net.ipv4.icmp_echo_ignore_broadcasts=1To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv4.icmp_echo_ignore_broadcasts = 1 |
Responding to broadcast (ICMP) echoes facilitates network mapping
and provides a vector for amplification attacks.
Ignoring ICMP echo requests (pings) sent to broadcast or multicast addresses makes the system slightly more difficult to enumerate on the network. |
| AC-7 (a) | An SELinux Context must be configured for default pam_tally2 file option | The file configuration option in PAM pam_tally2.so module defines where to keep counts. Default is /var/log/tallylog. The configured directory must have the correct SELinux context. | Not having the correct SELinux context on the pam_tally2.so file may lead to unauthorized access to the directory. |
| CM-7(a) CM-7(b) CM-6(a) AC-3(3)(a) AC-6 |
Ensure No Device Files are Unlabeled by SELinux |
Device files, which are used for communication with important system
resources, should be labeled with proper SELinux types. If any device files
carry the SELinux type device_t or unlabeled_t, report the
bug so that policy can be corrected. Supply information about what the
device is and what programs use it.
To check for incorrectly labeled device files, run following commands: $ sudo find /dev -context *:device_t:* \( -type c -o -type b \) -printf "%p %Z\n" $ sudo find /dev -context *:unlabeled_t:* \( -type c -o -type b \) -printf "%p %Z\n"It should produce no output in a well-configured system. |
If a device file carries the SELinux type device_t or unlabeled_t, then SELinux cannot properly restrict access to the device file. |
| SI-7 SI-7(1) CM-6(a) |
Configure Systemd Timer Execution of AIDE |
At a minimum, AIDE should be configured to run a weekly scan.
To implement a systemd service and a timer unit to run the service periodically:
For example, if a systemd timer is expected to be started every day at 5AM
OnCalendar=*-*-* 05:00:0 [Timer]section in the timer unit and a Unit section starting the AIDE check service unit should be referred. |
AIDE provides a means to check if unauthorized changes are made to the system. AIDE itself does not setup a periodic execution, so in order to detect unauthorized changes a systemd service to run the check and a systemd timer to take care of periodical execution of that systemd service should be defined. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Certmonger Service (certmonger) |
Certmonger is a D-Bus based service that attempts to simplify interaction
with certifying authorities on networks which use public-key infrastructure. It is often
combined with Red Hat's IPA (Identity Policy Audit) security information management
solution to aid in the management of certificates.
The certmonger service can be disabled with the following command:
$ sudo systemctl mask --now certmonger.service |
The services provided by certmonger may be essential for systems fulfilling some roles a PKI infrastructure, but its functionality is not necessary for many other use cases. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable RDS Support |
The Reliable Datagram Sockets (RDS) protocol is a transport
layer protocol designed to provide reliable high-bandwidth,
low-latency communications between nodes in a cluster.
To configure the system to prevent the rds
kernel module from being loaded, add the following line to the file /etc/modprobe.d/rds.conf:
install rds /bin/falseTo configure the system to prevent the rds from being used,
add the following line to file /etc/modprobe.d/rds.conf:
blacklist rds |
Disabling RDS protects the system against exploitation of any flaws in its implementation. |
| CM-7(a) CM-7(b) CM-6(a) |
Configure SSSD LDAP Backend to Use TLS For All Transactions |
The LDAP client should be configured to implement TLS for the integrity
of all remote LDAP authentication sessions. If the id_provider is
set to ldap or ipa in /etc/sssd/sssd.conf or any of the
/etc/sssd/sssd.conf.d configuration files, ldap_id_use_start_tls
must be set to true.
To check if LDAP is configured to use TLS when id_provider is set to ldap or ipa, use the following command: $ sudo grep -i ldap_id_use_start_tls /etc/sssd/sssd.conf /etc/sssd/conf.d/*.conf |
Without cryptographic integrity protections, information can be altered by unauthorized users without detection. The ssl directive specifies whether to use TLS or not. If not specified it will default to no. It should be set to start_tls rather than doing LDAP over SSL. |
| CM-7(a) CM-7(b) CM-6(a) IA-5(1)(c) |
Disable rlogin Service |
The rlogin service, which is available with
the rsh-server package and runs as a service through xinetd or separately
as a systemd socket, should be disabled.
If using xinetd, set disable to yes in /etc/xinetd.d/rlogin.
The rlogin socket can be disabled with the following command:
$ sudo systemctl mask --now rlogin.socket |
The rlogin service uses unencrypted network communications, which means that data from the login session, including passwords and all other information transmitted during the session, can be stolen by eavesdroppers on the network. |
| CM-7(a) CM-7(b) CM-6(a) IA-5(1)(c) |
Disable rexec Service |
The rexec service, which is available with the rsh-server package
and runs as a service through xinetd or separately as a systemd socket, should be disabled.
If using xinetd, set disable to yes in /etc/xinetd.d/rexec.
The rexec socket can be disabled with the following command:
$ sudo systemctl mask --now rexec.socket |
The rexec service uses unencrypted network communications, which means that data from the login session, including passwords and all other information transmitted during the session, can be stolen by eavesdroppers on the network. |
| CM-7(a) CM-7(b) CM-6(a) |
Authenticate Zone Transfers |
If it is necessary for a secondary nameserver to receive zone data
via zone transfer from the primary server, follow the instructions here. Use
dnssec-keygen to create a symmetric key file in the current directory:
$ cd /tmp $ sudo dnssec-keygen -a HMAC-MD5 -b 128 -n HOST dns.example.com Kdns.example.com .+aaa +iiiiiThis output is the name of a file containing the new key. Read the file to find the base64-encoded key string: $ sudo cat Kdns.example.com .+NNN +MMMMM .key dns.example.com IN KEY 512 3 157 base64-key-stringAdd the directives to /etc/named.conf on the primary server: key zone-transfer-key {
algorithm hmac-md5;
secret "base64-key-string ";
};
zone "example.com " IN {
type master;
allow-transfer { key zone-transfer-key; };
...
};
Add the directives below to /etc/named.conf on the secondary nameserver:
key zone-transfer-key {
algorithm hmac-md5;
secret "base64-key-string ";
};
server IP-OF-MASTER {
keys { zone-transfer-key; };
};
zone "example.com " IN {
type slave;
masters { IP-OF-MASTER ; };
...
};
|
The BIND transaction signature (TSIG) functionality allows primary and secondary nameservers to use a shared secret to verify authorization to perform zone transfers. This method is more secure than using IP-based limiting to restrict nameserver access, since IP addresses can be easily spoofed. However, if you cannot configure TSIG between your servers because, for instance, the secondary nameserver is not under your control and its administrators are unwilling to configure TSIG, you can configure an allow-transfer directive with numerical IP addresses or ACLs as a last resort. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Red Hat Subscription Manager Daemon (rhsmcertd) |
The Red Hat Subscription Manager (rhsmcertd) periodically checks for
changes in the entitlement certificates for a registered system and updates it
accordingly.
The rhsmcertd service can be disabled with the following command:
$ sudo systemctl mask --now rhsmcertd.service |
The rhsmcertd service can provide administrators with some additional control over which of their systems are entitled to particular subscriptions. However, for systems that are managed locally or which are not expected to require remote changes to their subscription status, it is unnecessary and can be disabled. |
| CM-7(a) CM-7(b) CM-6(a) |
Remove the GDM Package Group |
By removing the gdm package, the system no longer has GNOME installed
installed. If X Windows is not installed then the system cannot boot into graphical user mode.
This prevents the system from being accidentally or maliciously booted into a graphical.target
mode. To do so, run the following command:
$ sudo yum remove gdm |
Unnecessary service packages must not be installed to decrease the attack surface of the system. A graphical environment is unnecessary for certain types of systems including a virtualization hypervisor. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add nosuid Option to /var/log |
The nosuid mount option can be used to prevent
execution of setuid programs in /var/log. The SUID and SGID permissions
should not be required in directories containing log files.
Add the nosuid option to the fourth column of
/etc/fstab for the line which controls mounting of
/var/log.
|
The presence of SUID and SGID executables should be tightly controlled. Users should not be able to execute SUID or SGID binaries from partitions designated for log files. |
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall quagga Package |
The quagga package can be removed with the following command: $ sudo yum erase quagga |
Routing software is typically used on routers to exchange network topology information
with other routers. If routing software is used when not required, system network
information may be unnecessarily transmitted across the network.
If there is no need to make the router software available, removing it provides a safeguard against its activation. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable vsftpd Service |
The vsftpd service can be disabled with the following command:
$ sudo systemctl mask --now vsftpd.service |
Running FTP server software provides a network-based avenue of attack, and should be disabled if not needed. Furthermore, the FTP protocol is unencrypted and creates a risk of compromising sensitive information. |
| CM-7(a) CM-7(b) CM-6(a) CM-6(b) CM-6.1(iv) |
Disable Kernel Parameter for IPv6 Forwarding |
To set the runtime status of the net.ipv6.conf.all.forwarding kernel parameter, run the following command: $ sudo sysctl -w net.ipv6.conf.all.forwarding=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv6.conf.all.forwarding = 0 |
IP forwarding permits the kernel to forward packets from one network interface to another. The ability to forward packets between two networks is only appropriate for systems acting as routers. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable KDump Kernel Crash Analyzer (kdump) |
The kdump service provides a kernel crash dump analyzer. It uses the kexec
system call to boot a secondary kernel ("capture" kernel) following a system
crash, which can load information from the crashed kernel for analysis.
The kdump service can be disabled with the following command:
$ sudo systemctl mask --now kdump.service |
Kernel core dumps may contain the full contents of system memory at the time of the crash. Kernel core dumps consume a considerable amount of disk space and may result in denial of service by exhausting the available space on the target file system partition. Unless the system is used for kernel development or testing, there is little need to run the kdump service. |
| CM-7(a) CM-7(b) CM-6(a) CM-6(b) CM-6.1(iv) |
Disable Kernel Parameter for Accepting Source-Routed Packets on IPv6 Interfaces by Default |
To set the runtime status of the net.ipv6.conf.default.accept_source_route kernel parameter, run the following command: $ sudo sysctl -w net.ipv6.conf.default.accept_source_route=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv6.conf.default.accept_source_route = 0 |
Source-routed packets allow the source of the packet to suggest routers forward the packet along a different path than configured on the router, which can be used to bypass network security measures. This requirement applies only to the forwarding of source-routerd traffic, such as when IPv6 forwarding is enabled and the system is functioning as a router. Accepting source-routed packets in the IPv6 protocol has few legitimate uses. It should be disabled unless it is absolutely required. |
| IA-7 IA-7.1 |
Remove the Kerberos Server Package |
The krb5-server package should be removed if not in use.
Is this system the Kerberos server? If not, remove the package.
The krb5-server package can be removed with the following command:
$ sudo yum erase krb5-serverThe krb5-server RPM is not installed by default on a Red Hat Enterprise Linux 8 system. It is needed only by the Kerberos servers, not by the clients which use Kerberos for authentication. If the system is not intended for use as a Kerberos Server it should be removed. |
Unnecessary packages should not be installed to decrease the attack surface of the system. While this software is clearly essential on an KDC server, it is not necessary on typical desktop or workstation systems. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add noexec Option to /tmp |
The noexec mount option can be used to prevent binaries
from being executed out of /tmp.
Add the noexec option to the fourth column of
/etc/fstab for the line which controls mounting of
/tmp.
|
Allowing users to execute binaries from world-writable directories such as /tmp should never be necessary in normal operation and can expose the system to potential compromise. |
| CM-7(a) CM-7(b) CM-6(a) IA-5(1)(c) |
Disable rsh Service |
The rsh service, which is available with
the rsh-server package and runs as a service through xinetd or separately
as a systemd socket, should be disabled.
If using xinetd, set disable to yes in /etc/xinetd.d/rsh.
The rsh socket can be disabled with the following command:
$ sudo systemctl mask --now rsh.socket |
The rsh service uses unencrypted network communications, which means that data from the login session, including passwords and all other information transmitted during the session, can be stolen by eavesdroppers on the network. |
| CM-7(a) CM-7(b) CM-6(a) |
Deny Decline Messages |
Edit /etc/dhcp/dhcpd.conf and add or correct the following
global option to prevent the DHCP server from responding the DHCPDECLINE
messages, if possible: deny declines; |
The DHCPDECLINE message can be sent by a DHCP client to indicate that it does not consider the lease offered by the server to be valid. By issuing many DHCPDECLINE messages, a malicious client can exhaust the DHCP server's pool of IP addresses, causing the DHCP server to forget old address allocations. |
| CM-7(a) CM-7(b) CM-6(a) IA-5(1)(c) |
Disable telnet Service |
Make sure that the activation of the telnet service on system boot is disabled.
The telnet socket can be disabled with the following command:
$ sudo systemctl mask --now telnet.socket |
The telnet protocol uses unencrypted network communication, which means that data from the login session, including passwords and all other information transmitted during the session, can be stolen by eavesdroppers on the network. The telnet protocol is also subject to man-in-the-middle attacks. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Mounting of udf |
To configure the system to prevent the udf
kernel module from being loaded, add the following line to the file /etc/modprobe.d/udf.conf:
install udf /bin/falseTo configure the system to prevent the udf from being used,
add the following line to file /etc/modprobe.d/udf.conf:
blacklist udfThis effectively prevents usage of this uncommon filesystem. The udf filesystem type is the universal disk format used to implement the ISO/IEC 13346 and ECMA-167 specifications. This is an open vendor filesystem type for data storage on a broad range of media. This filesystem type is neccessary to support writing DVDs and newer optical disc formats. |
Removing support for unneeded filesystem types reduces the local attack surface of the system. |
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall Sendmail Package |
Sendmail is not the default mail transfer agent and is
not installed by default.
The sendmail package can be removed with the following command:
$ sudo yum erase sendmail |
The sendmail software was not developed with security in mind and its design prevents it from being effectively contained by SELinux. Postfix should be used instead. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable named Service |
The named service can be disabled with the following command:
$ sudo systemctl mask --now named.service |
All network services involve some risk of compromise due to implementation flaws and should be disabled if possible. |
| CM-7(a) CM-7(b) CM-6(a) AC-3(3)(a) AC-6 |
Ensure No Daemons are Unconfined by SELinux |
Daemons for which the SELinux policy does not contain rules will inherit the
context of the parent process. Because daemons are launched during
startup and descend from the init process, they inherit the unconfined_service_t context.
To check for unconfined daemons, run the following command: $ sudo ps -eZ | grep "unconfined_service_t"It should produce no output in a well-configured system. |
Daemons which run with the unconfined_service_t context may cause AVC denials, or allow privileges that the daemon does not require. |
| CM-7 (a) CM-7 (5) (b) |
Disable the uvcvideo module | If the device contains a camera it should be covered or disabled when not in use. | Failing to disconnect from collaborative computing devices (i.e., cameras) can result in subsequent compromises of organizational information. Providing easy methods to physically disconnect from such devices after a collaborative computing session helps to ensure participants actually carry out the disconnect activity without having to go through complex and tedious procedures. |
| CM-7(a) CM-7(b) CM-6(a) |
Remove the X Windows Package Group |
By removing the xorg-x11-server-common package, the system no longer has X Windows
installed. If X Windows is not installed then the system cannot boot into graphical user mode.
This prevents the system from being accidentally or maliciously booted into a graphical.target
mode. To do so, run the following command:$ sudo yum groupremove base-x $ sudo yum remove xorg-x11-server-common |
Unnecessary service packages must not be installed to decrease the attack surface of the system. X windows has a long history of security vulnerabilities and should not be installed unless approved and documented. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable DHCP Service |
The dhcpd service should be disabled on
any system that does not need to act as a DHCP server.
The dhcpd service can be disabled with the following command:
$ sudo systemctl mask --now dhcpd.service |
Unmanaged or unintentionally activated DHCP servers may provide faulty information to clients, interfering with the operation of a legitimate site DHCP server if there is one. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add nosuid Option to /var/log/audit |
The nosuid mount option can be used to prevent
execution of setuid programs in /var/log/audit. The SUID and SGID permissions
should not be required in directories containing audit log files.
Add the nosuid option to the fourth column of
/etc/fstab for the line which controls mounting of
/var/log/audit.
|
The presence of SUID and SGID executables should be tightly controlled. Users should not be able to execute SUID or SGID binaries from partitions designated for audit log files. |
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall nginx Package |
The nginx package can be removed with the following command:
$ sudo yum erase nginx |
If there is no need to make the web server software available, removing it provides a safeguard against its activation. |
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall the ssl compliant telnet server | The telnet daemon, even with ssl support, should be uninstalled. | telnet, even with ssl support, should not be installed. When remote shell is required, up-to-date ssh daemon can be used. |
| MP-7 CM-7(b) CM-6(a) |
Disable Booting from USB Devices in Boot Firmware | Configure the system boot firmware (historically called BIOS on PC systems) to disallow booting from USB drives. | Booting a system from a USB device would allow an attacker to circumvent any security measures provided by the operating system. Attackers could mount partitions and modify the configuration of the OS. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Client Dynamic DNS Updates | Dynamic DNS allows clients to dynamically update their own DNS records. The updates are transmitted by unencrypted means which can reveal information to a potential malicious user. If the system does not require Dynamic DNS, remove all DHCP_HOSTNAME references from the /etc/sysconfig/network-scripts/ifcfg-interface scripts. If dhclient is used, remove all send host-name hostname references from the /etc/dhclient.conf configuration file and/or any reference from the /etc/dhcp directory. | Dynamic DNS updates transmit unencrypted information about a system including its name and address and should not be used unless needed. |
| CM-7(a) CM-7(b) CM-6(a) MP-7 |
Disable Modprobe Loading of USB Storage Driver |
To prevent USB storage devices from being used, configure the kernel module loading system
to prevent automatic loading of the USB storage driver.
To configure the system to prevent the usb-storage
kernel module from being loaded, add the following line to the file /etc/modprobe.d/usb-storage.conf:
install usb-storage /bin/falseTo configure the system to prevent the usb-storage from being used,
add the following line to file /etc/modprobe.d/usb-storage.conf:
blacklist usb-storageThis will prevent the modprobe program from loading the usb-storage module, but will not prevent an administrator (or another program) from using the insmod program to load the module manually. |
USB storage devices such as thumb drives can be used to introduce malicious software. |
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall the inet-based telnet server | The inet-based telnet daemon should be uninstalled. | telnet allows clear text communications, and does not protect any data transmission between client and server. Any confidential data can be listened and no integrity checking is made. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Printer Browsing Entirely if Possible |
By default, CUPS listens on the network for printer list
broadcasts on UDP port 631. This functionality is called printer browsing.
To disable printer browsing entirely, edit the CUPS configuration
file, located at /etc/cups/cupsd.conf, to include the following:
Browsing Off BrowseAllow none |
The CUPS print service can be configured to broadcast a list of available printers to the network. Other systems on the network, also running the CUPS print service, can be configured to listen to these broadcasts and add and configure these printers for immediate use. By disabling this browsing capability, the system will no longer generate or receive such broadcasts. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable tftp Service |
The tftp service should be disabled.
The tftp service can be disabled with the following command:
$ sudo systemctl mask --now tftp.service |
Disabling the tftp service ensures the system is not acting as a TFTP server, which does not provide encryption or authentication. |
| CM-7(a) CM-7(b) CM-6(a) SC-7(a) |
Disable Accepting ICMP Redirects for All IPv4 Interfaces |
To set the runtime status of the net.ipv4.conf.all.accept_redirects kernel parameter, run the following command: $ sudo sysctl -w net.ipv4.conf.all.accept_redirects=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv4.conf.all.accept_redirects = 0 |
ICMP redirect messages are used by routers to inform hosts that a more
direct route exists for a particular destination. These messages modify the
host's route table and are unauthenticated. An illicit ICMP redirect
message could result in a man-in-the-middle attack.
This feature of the IPv4 protocol has few legitimate uses. It should be disabled unless absolutely required." |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Mounting of jffs2 |
To configure the system to prevent the jffs2
kernel module from being loaded, add the following line to the file /etc/modprobe.d/jffs2.conf:
install jffs2 /bin/falseTo configure the system to prevent the jffs2 from being used,
add the following line to file /etc/modprobe.d/jffs2.conf:
blacklist jffs2This effectively prevents usage of this uncommon filesystem. |
Linux kernel modules which implement filesystems that are not needed by the local system should be disabled. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add nodev Option to /boot |
The nodev mount option can be used to prevent device files from
being created in /boot.
Legitimate character and block devices should exist only in
the /dev directory on the root partition or within chroot
jails built for system services.
Add the nodev option to the fourth column of
/etc/fstab for the line which controls mounting of
/boot.
|
The only legitimate location for device files is the /dev directory located on the root partition. The only exception to this is chroot jails. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Avahi Publishing |
To prevent Avahi from publishing its records, edit /etc/avahi/avahi-daemon.conf
and ensure the following line appears in the [publish] section:
disable-publishing=yes |
This helps ensure that no record will be published by Avahi. |
| CM-7(a) CM-7(b) CM-6(a) SC-7(a) |
Disable Kernel Parameter for Accepting Secure ICMP Redirects on all IPv4 Interfaces |
To set the runtime status of the net.ipv4.conf.all.secure_redirects kernel parameter, run the following command: $ sudo sysctl -w net.ipv4.conf.all.secure_redirects=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv4.conf.all.secure_redirects = 0 |
Accepting "secure" ICMP redirects (from those gateways listed as default gateways) has few legitimate uses. It should be disabled unless it is absolutely required. |
| AC-7(b) CM-6(a) |
Ensure the Logon Failure Delay is Set Correctly in login.defs |
To ensure the logon failure delay controlled by /etc/login.defs is set properly,
add or correct the FAIL_DELAY setting in /etc/login.defs to read as follows:
FAIL_DELAY 4 |
Increasing the time between a failed authentication attempt and re-prompting to enter credentials helps to slow a single-threaded brute force attack. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable GNOME3 Automount running |
The system's default desktop environment, GNOME3, will mount
devices and removable media (such as DVDs, CDs and USB flash drives) whenever
they are inserted into the system. To disable autorun-never within GNOME3, add or set
autorun-never to true in /etc/dconf/db/local.d/00-security-settings.
For example:
[org/gnome/desktop/media-handling] autorun-never=trueOnce the settings have been added, add a lock to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification. For example: /org/gnome/desktop/media-handling/autorun-neverAfter the settings have been set, run dconf update. |
Automatically mounting file systems permits easy introduction of unknown devices, thereby facilitating malicious activity. Disabling automatic mount running in GNOME3 can prevent the introduction of malware via removable media. It will, however, also prevent desktop users from legitimate use of removable media. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Mounting of vFAT filesystems |
To configure the system to prevent the vfat
kernel module from being loaded, add the following line to the file /etc/modprobe.d/vfat.conf:
install vfat /bin/falseTo configure the system to prevent the vfat from being used,
add the following line to file /etc/modprobe.d/vfat.conf:
blacklist vfatThis effectively prevents usage of this uncommon filesystem. The vFAT filesystem format is primarily used on older windows systems and portable USB drives or flash modules. It comes in three types FAT12, FAT16, and FAT32 all of which are supported by the vfat kernel module. |
Removing support for unneeded filesystems reduces the local attack surface of the system. |
| CM-7(a) CM-7(b) CM-6(a) CM-6(b) CM-6.1(iv) |
Disable Accepting ICMP Redirects for All IPv6 Interfaces |
To set the runtime status of the net.ipv6.conf.all.accept_redirects kernel parameter, run the following command: $ sudo sysctl -w net.ipv6.conf.all.accept_redirects=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv6.conf.all.accept_redirects = 0 |
An illicit ICMP redirect message could result in a man-in-the-middle attack. |
| CM-7(a) CM-7(b) CM-6(a) |
Set httpd ServerTokens Directive to Prod |
ServerTokens Prod restricts information in page headers, returning only the word "Apache."
Add or correct the following directive in /etc/httpd/conf/httpd.conf: ServerTokens Prod |
Information disclosed to clients about the configuration of the web server and system could be used to plan an attack on the given system. This information disclosure should be restricted to a minimum. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable the CUPS Service |
The cups service can be disabled with the following command:
$ sudo systemctl mask --now cups.service |
Turn off unneeded services to reduce attack surface. |
| CM-7(a) CM-7(b) SC-5 SC-7(a) |
Configure Kernel Parameter for Accepting Secure Redirects By Default |
To set the runtime status of the net.ipv4.conf.default.secure_redirects kernel parameter, run the following command: $ sudo sysctl -w net.ipv4.conf.default.secure_redirects=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv4.conf.default.secure_redirects = 0 |
Accepting "secure" ICMP redirects (from those gateways listed as default gateways) has few legitimate uses. It should be disabled unless it is absolutely required. |
| CM-7(a) CM-7(b) SC-5 CM-6(a) SC-7(a) |
Disable Kernel Parameter for Sending ICMP Redirects on all IPv4 Interfaces by Default |
To set the runtime status of the net.ipv4.conf.default.send_redirects kernel parameter, run the following command: $ sudo sysctl -w net.ipv4.conf.default.send_redirects=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv4.conf.default.send_redirects = 0 |
ICMP redirect messages are used by routers to inform hosts that a more
direct route exists for a particular destination. These messages contain information
from the system's route table possibly revealing portions of the network topology.
The ability to send ICMP redirects is only appropriate for systems acting as routers. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Kernel Parameter for Accepting Source-Routed Packets on all IPv6 Interfaces |
To set the runtime status of the net.ipv6.conf.all.accept_source_route kernel parameter, run the following command: $ sudo sysctl -w net.ipv6.conf.all.accept_source_route=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv6.conf.all.accept_source_route = 0 |
Source-routed packets allow the source of the packet to suggest routers
forward the packet along a different path than configured on the router, which can
be used to bypass network security measures. This requirement applies only to the
forwarding of source-routerd traffic, such as when IPv6 forwarding is enabled and
the system is functioning as a router.
Accepting source-routed packets in the IPv6 protocol has few legitimate uses. It should be disabled unless it is absolutely required. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Quagga Service |
The zebra service can be disabled with the following command:
$ sudo systemctl mask --now zebra.service |
Routing protocol daemons are typically used on routers to exchange network topology information with other routers. If routing daemons are used when not required, system network information may be unnecessarily transmitted across the network. |
| SI-7 SI-7(1) CM-6(a) |
Configure AIDE to Use FIPS 140-2 for Validating Hashes |
By default, the sha512 option is added to the NORMAL ruleset in AIDE.
If using a custom ruleset or the sha512 option is missing, add sha512
to the appropriate ruleset.
For example, add sha512 to the following line in /etc/aide.conf:
NORMAL = FIPSR+sha512AIDE rules can be configured in multiple ways; this is merely one example that is already configured by default. |
File integrity tools use cryptographic hashes for verifying file contents and directories have not been altered. These hashes must be FIPS 140-2 approved cryptographic hashes. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add nodev Option to /var/log |
The nodev mount option can be used to prevent device files from
being created in /var/log.
Legitimate character and block devices should exist only in
the /dev directory on the root partition or within chroot
jails built for system services.
Add the nodev option to the fourth column of
/etc/fstab for the line which controls mounting of
/var/log.
|
The only legitimate location for device files is the /dev directory located on the root partition. The only exception to this is chroot jails. |
| CM-7(a) | Disable vsyscalls |
To disable use of virtual syscalls,
add the argument vsyscall=none to the default
GRUB 2 command line for the Linux operating system.
To ensure that vsyscall=none is added as a kernel command line
argument to newly installed kernels, add vsyscall=none to the
default Grub2 command line for Linux operating systems. Modify the line within
/etc/default/grub as shown below:
GRUB_CMDLINE_LINUX="... vsyscall=none ..."Run the following command to update command line for already installed kernels: # grubby --update-kernel=ALL --args="vsyscall=none" |
Virtual Syscalls provide an opportunity of attack for a user who has control of the return instruction pointer. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add noexec Option to /var/log/audit |
The noexec mount option can be used to prevent binaries
from being executed out of /var/log/audit.
Add the noexec option to the fourth column of
/etc/fstab for the line which controls mounting of
/var/log/audit.
|
Allowing users to execute binaries from directories containing audit log files such as /var/log/audit should never be necessary in normal operation and can expose the system to potential compromise. |
| CM-7(a) CM-7(b) CM-6(a) |
Configure Accepting Router Advertisements on All IPv6 Interfaces |
To set the runtime status of the net.ipv6.conf.all.accept_ra kernel parameter, run the following command: $ sudo sysctl -w net.ipv6.conf.all.accept_ra=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv6.conf.all.accept_ra = 0 |
An illicit router advertisement message could result in a man-in-the-middle attack. |
| CM-7(a) CM-7(b) SC-5(3)(a) |
Enable Kernel Paremeter to Log Martian Packets on all IPv4 Interfaces by Default |
To set the runtime status of the net.ipv4.conf.default.log_martians kernel parameter, run the following command: $ sudo sysctl -w net.ipv4.conf.default.log_martians=1To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv4.conf.default.log_martians = 1 |
The presence of "martian" packets (which have impossible addresses) as well as spoofed packets, source-routed packets, and redirects could be a sign of nefarious network activity. Logging these packets enables this activity to be detected. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Apache Qpid (qpidd) |
The qpidd service provides high speed, secure,
guaranteed delivery services. It is an implementation of the Advanced Message
Queuing Protocol. By default the qpidd service will bind to port 5672 and
listen for connection attempts.
The qpidd service can be disabled with the following command:
$ sudo systemctl mask --now qpidd.service |
The qpidd service is automatically installed when the base package selection is selected during installation. The qpidd service listens for network connections, which increases the attack surface of the system. If the system is not intended to receive AMQP traffic, then the qpidd service is not needed and should be disabled or removed. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add nodev Option to /tmp |
The nodev mount option can be used to prevent device files from
being created in /tmp. Legitimate character and block devices
should not exist within temporary directories like /tmp.
Add the nodev option to the fourth column of
/etc/fstab for the line which controls mounting of
/tmp.
|
The only legitimate location for device files is the /dev directory located on the root partition. The only exception to this is chroot jails. |
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall CUPS Package |
The cups package can be removed with the following command:
$ sudo yum erase cups |
If the system does not need to print jobs or accept print jobs from other systems, it is recommended that CUPS be removed to reduce the potential attack surface. |
| CM-7(a) CM-7(b) SC-5 SC-7(a) |
Disable Kernel Parameter for Accepting Source-Routed Packets on IPv4 Interfaces by Default |
To set the runtime status of the net.ipv4.conf.default.accept_source_route kernel parameter, run the following command: $ sudo sysctl -w net.ipv4.conf.default.accept_source_route=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv4.conf.default.accept_source_route = 0 |
Source-routed packets allow the source of the packet to suggest routers
forward the packet along a different path than configured on the router,
which can be used to bypass network security measures.
Accepting source-routed packets in the IPv4 protocol has few legitimate uses. It should be disabled unless it is absolutely required, such as when IPv4 forwarding is enabled and the system is legitimately functioning as a router. |
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall tftp-server Package |
The tftp-server package can be removed with the following command: $ sudo yum erase tftp-server |
Removing the tftp-server package decreases the risk of the accidental
(or intentional) activation of tftp services.
If TFTP is required for operational support (such as transmission of router configurations), its use must be documented with the Information Systems Securty Manager (ISSM), restricted to only authorized personnel, and have access control rules established. |
| CM-7(a) CM-7(b) CM-6(a) MP-7 |
Disable the Automounter |
The autofs daemon mounts and unmounts filesystems, such as user
home directories shared via NFS, on demand. In addition, autofs can be used to handle
removable media, and the default configuration provides the cdrom device as /misc/cd.
However, this method of providing access to removable media is not common, so autofs
can almost always be disabled if NFS is not in use. Even if NFS is required, it may be
possible to configure filesystem mounts statically by editing /etc/fstab
rather than relying on the automounter.
The autofs service can be disabled with the following command:
$ sudo systemctl mask --now autofs.service |
Disabling the automounter permits the administrator to
statically control filesystem mounting through /etc/fstab.
Additionally, automatically mounting filesystems permits easy introduction of unknown devices, thereby facilitating malicious activity. |
| CM-7(a) CM-7(b) CM-6(a) |
Ensure rsyslog Does Not Accept Remote Messages Unless Acting As Log Server |
The rsyslog daemon should not accept remote messages unless the system acts as a log
server. To ensure that it is not listening on the network, ensure any of the following lines
are not found in rsyslog configuration files.
If using legacy syntax:
$ModLoad imtcp $InputTCPServerRun port $ModLoad imudp $UDPServerRun port $ModLoad imrelp $InputRELPServerRun portIf using RainerScript syntax: module(load="imtcp") module(load="imudp") input(type="imtcp" port="514") input(type="imudp" port="514") |
Any process which receives messages from the network incurs some risk of receiving malicious messages. This risk can be eliminated for rsyslog by configuring it not to listen on the network. |
| CM-7(a) CM-7(b) CM-6(a) IA-2 IA-2(8) IA-2(9) AC-17(a) |
Mount Remote Filesystems with Kerberos Security |
Add the sec=krb5:krb5i:krb5p option to the fourth column of /etc/fstab for the line which controls mounting of
any NFS mounts.
|
When an NFS server is configured to use AUTH_SYS a selected userid and groupid are used to handle requests from the remote user. The userid and groupid could mistakenly or maliciously be set incorrectly. The AUTH_GSS method of authentication uses certificates on the server and client systems to more securely authenticate the remote mount request. |
| CM-7(a) CM-7(b) CM-6(a) |
Restrict Information Published by Avahi |
If it is necessary to publish some information to the network, it should not be joined
by any extraneous information, or by information supplied by a non-trusted source
on the system.
Prevent user applications from using Avahi to publish services by adding or
correcting the following line in the [publish] section:
disable-user-service-publishing=yesImplement as many of the following lines as possible, to restrict the information published by Avahi. publish-addresses=no publish-hinfo=no publish-workstation=no publish-domain=noInspect the files in the directory /etc/avahi/services/. Unless there is an operational need to publish information about each of these services, delete the corresponding file. |
These options prevent publishing attempts from succeeding, and can be applied even if publishing is disabled entirely via disable-publishing. Alternatively, these can be used to restrict the types of published information in the event that some information must be published. |
| CM-7(a) | Disable vsyscalls | To disable use of virtual syscalls, add the argument vsyscall=none to all BLS (Boot Loader Specification) entries ('options' line) for the Linux operating system in /boot/loader/entries/*.conf. | Virtual Syscalls provide an opportunity of attack for a user who has control of the return instruction pointer. |
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall telnet-server Package |
The telnet-server package can be removed with the following command:
$ sudo yum erase telnet-server |
It is detrimental for operating systems to provide, or install by default,
functionality exceeding requirements or mission objectives. These
unnecessary capabilities are often overlooked and therefore may remain
unsecure. They increase the risk to the platform by providing additional
attack vectors.
The telnet service provides an unencrypted remote access service which does not provide for the confidentiality and integrity of user passwords or the remote session. If a privileged user were to login using this service, the privileged user password could be compromised. Removing the telnet-server package decreases the risk of the telnet service's accidental (or intentional) activation. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Accepting Router Advertisements on all IPv6 Interfaces by Default |
To set the runtime status of the net.ipv6.conf.default.accept_ra kernel parameter, run the following command: $ sudo sysctl -w net.ipv6.conf.default.accept_ra=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv6.conf.default.accept_ra = 0 |
An illicit router advertisement message could result in a man-in-the-middle attack. |
| CM-7(a) CM-7(b) CM-6(a) SC-7(a) |
Enable Kernel Parameter to Use Reverse Path Filtering on all IPv4 Interfaces |
To set the runtime status of the net.ipv4.conf.all.rp_filter kernel parameter, run the following command: $ sudo sysctl -w net.ipv4.conf.all.rp_filter=1To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv4.conf.all.rp_filter = 1 |
Enabling reverse path filtering drops packets with source addresses that should not have been able to be received on the interface they were received on. It should not be used on systems which are routers for complicated networks, but is helpful for end hosts and routers serving small networks. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Portreserve (portreserve) |
The portreserve service is a TCP port reservation utility that can
be used to prevent portmap from binding to well known TCP ports that are
required for other services.
The portreserve service can be disabled with the following command:
$ sudo systemctl mask --now portreserve.service |
The portreserve service provides helpful functionality by preventing conflicting usage of ports in the reserved port range, but it can be disabled if not needed. |
| CM-7(a) CM-7(b) CM-6(a) |
Do Not Use Dynamic DNS |
To prevent the DHCP server from receiving DNS information from
clients, edit /etc/dhcp/dhcpd.conf, and add or correct the following global
option: ddns-update-style none; |
The Dynamic DNS protocol is used to remotely update the data served by a DNS server. DHCP servers can use Dynamic DNS to publish information about their clients. This setup carries security risks, and its use is not recommended. If Dynamic DNS must be used despite the risks it poses, it is critical that Dynamic DNS transactions be protected using TSIG or some other cryptographic authentication mechanism. See dhcpd.conf(5) for more information about protecting the DHCP server from passing along malicious DNS data from its clients. |
| AC-7(a) AU-7(1) AU-7(2) AU-14 AU-12(2) AU-2(a) CM-6(a) |
Ensure the audit-libs package as a part of audit Subsystem is Installed | The audit-libs package should be installed. | The auditd service is an access monitoring and accounting daemon, watching system calls to audit any access, in comparison with potential local access control policy such as SELinux policy. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add nosuid Option to /home |
The nosuid mount option can be used to prevent
execution of setuid programs in /home. The SUID and SGID permissions
should not be required in these user data directories.
Add the nosuid option to the fourth column of
/etc/fstab for the line which controls mounting of
/home.
|
The presence of SUID and SGID executables should be tightly controlled. Users should not be able to execute SUID or SGID binaries from user home directory partitions. |
| MP-7 CM-6(a) |
Disable Kernel Support for USB via Bootloader Configuration | All USB support can be disabled by adding the nousb argument to the kernel's boot loader configuration. To do so, Add the nousb kernel argument via a MachineConfig object. | Disabling the USB subsystem within the Linux kernel at system boot will protect against potentially malicious USB devices, although it is only practical in specialized systems. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable IPv6 Networking Support Automatic Loading |
To prevent the IPv6 kernel module (ipv6) from binding to the
IPv6 networking stack, add the following line to
/etc/modprobe.d/disabled.conf (or another file in
/etc/modprobe.d):
options ipv6 disable=1This permits the IPv6 module to be loaded (and thus satisfy other modules that depend on it), while disabling support for the IPv6 protocol. |
Any unnecessary network stacks - including IPv6 - should be disabled, to reduce the vulnerability to exploitation. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable GNOME3 Automounting |
The system's default desktop environment, GNOME3, will mount
devices and removable media (such as DVDs, CDs and USB flash drives) whenever
they are inserted into the system. To disable automount within GNOME3, add or set
automount to false in /etc/dconf/db/local.d/00-security-settings.
For example:
[org/gnome/desktop/media-handling] automount=falseOnce the settings have been added, add a lock to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification. For example: /org/gnome/desktop/media-handling/automountAfter the settings have been set, run dconf update. |
Disabling automatic mounting in GNOME3 can prevent the introduction of malware via removable media. It will, however, also prevent desktop users from legitimate use of removable media. |
| CM-7(a) CM-7(b) SC-5(1) SC-5(2) SC-5(3)(a) CM-6(a) |
Enable Kernel Parameter to Use TCP Syncookies on Network Interfaces |
To set the runtime status of the net.ipv4.tcp_syncookies kernel parameter, run the following command: $ sudo sysctl -w net.ipv4.tcp_syncookies=1To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv4.tcp_syncookies = 1 |
A TCP SYN flood attack can cause a denial of service by filling a system's TCP connection table with connections in the SYN_RCVD state. Syncookies can be used to track a connection when a subsequent ACK is received, verifying the initiator is attempting a valid connection and is not a flood source. This feature is activated when a flood condition is detected, and enables the system to continue servicing valid connection requests. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add noexec Option to /dev/shm |
The noexec mount option can be used to prevent binaries
from being executed out of /dev/shm.
It can be dangerous to allow the execution of binaries
from world-writable temporary storage directories such as /dev/shm.
Add the noexec option to the fourth column of
/etc/fstab for the line which controls mounting of
/dev/shm.
|
Allowing users to execute binaries from world-writable directories such as /dev/shm can expose the system to potential compromise. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable At Service (atd) |
The at and batch commands can be used to
schedule tasks that are meant to be executed only once. This allows delayed
execution in a manner similar to cron, except that it is not
recurring. The daemon atd keeps track of tasks scheduled via
at and batch, and executes them at the specified time.
The atd service can be disabled with the following command:
$ sudo systemctl mask --now atd.service |
The atd service could be used by an unsophisticated insider to carry out activities outside of a normal login session, which could complicate accountability. Furthermore, the need to schedule tasks with at or batch is not common. |
| CM-7(a) CM-7(b) CM-6(a) |
Deny BOOTP Queries |
Unless your network needs to support older BOOTP clients, disable
support for the bootp protocol by adding or correcting the global option:
deny bootp; |
The bootp option tells dhcpd to respond to BOOTP queries. If support for this simpler protocol is not needed, it should be disabled to remove attack vectors against the DHCP server. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Odd Job Daemon (oddjobd) |
The oddjobd service exists to provide an interface and
access control mechanism through which
specified privileged tasks can run tasks for unprivileged client
applications. Communication with oddjobd through the system message bus.
The oddjobd service can be disabled with the following command:
$ sudo systemctl mask --now oddjobd.service |
The oddjobd service may provide necessary functionality in some environments, and can be disabled if it is not needed. Execution of tasks by privileged programs, on behalf of unprivileged ones, has traditionally been a source of privilege escalation security issues. |
| CM-7(a) CM-7(b) CM-6(a) CM-7(2) MA-3 |
Ensure System is Not Acting as a Network Sniffer |
The system should not be acting as a network sniffer, which can
capture all traffic on the network to which it is connected. Run the following
to determine if any interface is running in promiscuous mode:
$ ip link | grep PROMISCPromiscuous mode of an interface can be disabled with the following command: $ sudo ip link set dev device_name multicast off promisc off |
Network interfaces in promiscuous mode allow for the capture of all network traffic
visible to the system. If unauthorized individuals can access these applications, it
may allow them to collect information such as logon IDs, passwords, and key exchanges
between systems.
If the system is being used to perform a network troubleshooting function, the use of these tools must be documented with the Information Systems Security Manager (ISSM) and restricted to only authorized personnel. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Mounting of cramfs |
To configure the system to prevent the cramfs
kernel module from being loaded, add the following line to the file /etc/modprobe.d/cramfs.conf:
install cramfs /bin/falseTo configure the system to prevent the cramfs from being used,
add the following line to file /etc/modprobe.d/cramfs.conf:
blacklist cramfsThis effectively prevents usage of this uncommon filesystem. The cramfs filesystem type is a compressed read-only Linux filesystem embedded in small footprint systems. A cramfs image can be used without having to first decompress the image. |
Removing support for unneeded filesystem types reduces the local attack surface of the server. |
| CM-7(a) CM-7(b) CM-6(a) IA-5(1)(c) IA-5(1).1(v) CM-7 CM-7.1(ii) |
Uninstall vsftpd Package |
The vsftpd package can be removed with the following command: $ sudo yum erase vsftpd |
Removing the vsftpd package decreases the risk of its accidental activation. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Avahi Server Software |
The avahi-daemon service can be disabled with the following command:
$ sudo systemctl mask --now avahi-daemon.service |
Because the Avahi daemon service keeps an open network port, it is subject to network attacks. Its functionality is convenient but is only appropriate if the local network can be trusted. |
| IA-7 IA-7.1 |
Set PAM's Common Authentication Hashing Algorithm |
The PAM system service can be configured to only store encrypted
representations of passwords. In
/etc/pam.d/common-auth,
the
auth section of the file controls which PAM modules execute
during a password change. Set the pam_unix.so module in the
auth section to include the argument sha512, as shown
below:
auth required pam_unix.so sha512 other arguments... This will help ensure when local users change their authentication method, hashes for the new authentications will be generated using the SHA-512 algorithm. This is the default. |
Unapproved mechanisms used for authentication to the cryptographic module are not verified and therefore cannot be relied on to provide confidentiality or integrity, and data may be compromised. This setting ensures user and group account administration utilities are configured to store only encrypted representations of passwords. Additionally, the crypt_style configuration option ensures the use of a strong hashing algorithm that makes password cracking attacks more difficult. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable ntpdate Service (ntpdate) |
The ntpdate service sets the local hardware clock by polling NTP servers
when the system boots. It synchronizes to the NTP servers listed in
/etc/ntp/step-tickers or /etc/ntp.conf
and then sets the local hardware clock to the newly synchronized
system time.
The ntpdate service can be disabled with the following command:
$ sudo systemctl mask --now ntpdate.service |
The ntpdate service may only be suitable for systems which are rebooted frequently enough that clock drift does not cause problems between reboots. In any event, the functionality of the ntpdate service is now available in the ntpd program and should be considered deprecated. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable IPv6 Addressing on All IPv6 Interfaces |
To disable support for (ipv6) addressing on all interface add the following line to
/etc/sysctl.d/ipv6.conf (or another file in /etc/sysctl.d):
net.ipv6.conf.all.disable_ipv6 = 1This disables IPv6 on all network interfaces as other services and system functionality require the IPv6 stack loaded to work. |
Any unnecessary network stacks - including IPv6 - should be disabled, to reduce the vulnerability to exploitation. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable anacron Service |
The cronie-anacron package, which provides anacron
functionality, is installed by default.
The cronie-anacron package can be removed with the following command:
$ sudo yum erase cronie-anacron |
The anacron service provides cron functionality for systems such as laptops and workstations that may be shut down during the normal times that cron jobs are scheduled to run. On systems which do not require this additional functionality, anacron could needlessly increase the possible attack surface for an intruder. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable All GNOME3 Thumbnailers |
The system's default desktop environment, GNOME3, uses
a number of different thumbnailer programs to generate thumbnails
for any new or modified content in an opened folder. To disable the
execution of these thumbnail applications, add or set disable-all
to true in /etc/dconf/db/local.d/00-security-settings.
For example:
[org/gnome/desktop/thumbnailers] disable-all=trueOnce the settings have been added, add a lock to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification. For example: /org/gnome/desktop/thumbnailers/disable-allAfter the settings have been set, run dconf update. This effectively prevents an attacker from gaining access to a system through a flaw in GNOME3's Nautilus thumbnail creators. |
An attacker with knowledge of a flaw in a GNOME3 thumbnailer application could craft a malicious file to exploit this flaw. Assuming the attacker could place the malicious file on the local filesystem (via a web upload for example) and assuming a user browses the same location using Nautilus, the malicious file would exploit the thumbnailer with the potential for malicious code execution. It is best to disable these thumbnailer applications unless they are explicitly required. |
| AC-7 (a) | Account Lockouts Must Be Logged | PAM faillock locks an account due to excessive password failures, this event must be logged. | Without auditing of these events it may be harder or impossible to identify what an attacker did after an attack. |
| CM-7 (2) CM-7 (5) (b) CM-6 b |
Configure Fapolicy Module to Employ a Deny-all, Permit-by-exception Policy to Allow the Execution of Authorized Software Programs. | The Fapolicy module must be configured to employ a deny-all, permit-by-exception policy to allow the execution of authorized software programs and to prevent unauthorized software from running. | Utilizing a whitelist provides a configuration management method for allowing the execution of only authorized software. Using only authorized software decreases risk by limiting the number of potential vulnerabilities. Verification of whitelisted software occurs prior to execution or at system startup. Proceed with caution with enforcing the use of this daemon. Improper configuration may render the system non-functional. The "fapolicyd" API is not namespace aware and can cause issues when launching or running containers. |
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall avahi-autoipd Server Package | If the system does not need to have an Avahi server which implements the DNS Service Discovery and Multicast DNS protocols, the avahi-autoipd and avahi packages can be uninstalled. | Automatic discovery of network services is not normally required for system functionality. It is recommended to remove this package to reduce the potential attack surface. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Network File System (nfs) |
The Network File System (NFS) service allows remote hosts to mount
and interact with shared filesystems on the local system. If the local system
is not designated as a NFS server then this service should be disabled.
The nfs-server service can be disabled with the following command:
$ sudo systemctl mask --now nfs-server.service |
Unnecessary services should be disabled to decrease the attack surface of the system. |
| CM-7(a) CM-7(b) CM-6(a) |
Remove Rsh Trust Files |
The files /etc/hosts.equiv and ~/.rhosts (in
each user's home directory) list remote hosts and users that are trusted by the
local system when using the rshd daemon.
To remove these files, run the following command to delete them from any
location:
$ sudo rm /etc/hosts.equiv $ rm ~/.rhosts |
This action is only meaningful if .rhosts support is permitted through PAM. Trust files are convenient, but when used in conjunction with the R-services, they can allow unauthenticated access to a system. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable GNOME3 Automount Opening |
The system's default desktop environment, GNOME3, will mount
devices and removable media (such as DVDs, CDs and USB flash drives) whenever
they are inserted into the system. To disable automount-open within GNOME3, add or set
automount-open to false in /etc/dconf/db/local.d/00-security-settings.
For example:
[org/gnome/desktop/media-handling] automount-open=falseOnce the settings have been added, add a lock to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification. For example: /org/gnome/desktop/media-handling/automount-openAfter the settings have been set, run dconf update. |
Automatically mounting file systems permits easy introduction of unknown devices, thereby facilitating malicious activity. Disabling automatic mounting in GNOME3 can prevent the introduction of malware via removable media. It will, however, also prevent desktop users from legitimate use of removable media. |
| CM-7(a) CM-7(b) CM-6(a) AC-3 AC-17(a) |
Restrict Access to Anonymous Users if Possible |
Is there a mission-critical reason for users to transfer files to/from their own accounts
using FTP, rather than using a secure protocol like SCP/SFTP? If not, edit the vsftpd
configuration file. Add or correct the following configuration option:
local_enable=NOIf non-anonymous FTP logins are necessary, follow the guidance in the remainder of this section to secure these logins as much as possible. |
The use of non-anonymous FTP logins is strongly discouraged. Since SSH clients and servers are widely available, and since SSH provides support for a transfer mode which resembles FTP in user interface, there is no good reason to allow password-based FTP access.' |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add nodev Option to /dev/shm |
The nodev mount option can be used to prevent creation of device
files in /dev/shm. Legitimate character and block devices should
not exist within temporary directories like /dev/shm.
Add the nodev option to the fourth column of
/etc/fstab for the line which controls mounting of
/dev/shm.
|
The only legitimate location for device files is the /dev directory located on the root partition. The only exception to this is chroot jails. |
| CM-7(a) CM-7(b) CM-6(a) AC-6(1) |
Set Permissions on the /var/log/httpd/ Directory |
Ensure that the permissions on the web server log directory is set to 700:
$ sudo chmod 700 /var/log/httpd/This is its default setting. |
A major tool in exploring the web site use, attempted use, unusual conditions, and problems are the access and error logs. In the event of a security incident, these logs can provide the SA and the web manager with valuable information. To ensure the integrity of the log files and protect the SA and the web manager from a conflict of interest related to the maintenance of these files, only the members of the Auditors group will be granted permissions to move, copy, and delete these files in the course of their duties related to the archiving of these files. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add nosuid Option to /tmp |
The nosuid mount option can be used to prevent
execution of setuid programs in /tmp. The SUID and SGID permissions
should not be required in these world-writable directories.
Add the nosuid option to the fourth column of
/etc/fstab for the line which controls mounting of
/tmp.
|
The presence of SUID and SGID executables should be tightly controlled. Users should not be able to execute SUID or SGID binaries from temporary storage partitions. |
| AC-7 (a) | Account Lockouts Must Be Logged | PAM faillock locks an account due to excessive password failures, this event must be logged. | Without auditing of these events it may be harder or impossible to identify what an attacker did after an attack. |
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall bind Package |
The named service is provided by the bind package.
The bind package can be removed with the following command:
$ sudo yum erase bind |
If there is no need to make DNS server software available, removing it provides a safeguard against its activation. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Postfix Network Listening |
Edit the file /etc/postfix/main.cf to ensure that only the following
inet_interfaces line appears:
inet_interfaces = loopback-only |
This ensures postfix accepts mail messages (such as cron job reports) from the local system only, and not from the network, which protects it from network attack. |
| CM-7(a) CM-7(b) SC-5 CM-6(a) SC-7(a) |
Disable Kernel Parameter for Accepting Source-Routed Packets on all IPv4 Interfaces |
To set the runtime status of the net.ipv4.conf.all.accept_source_route kernel parameter, run the following command: $ sudo sysctl -w net.ipv4.conf.all.accept_source_route=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv4.conf.all.accept_source_route = 0 |
Source-routed packets allow the source of the packet to suggest routers
forward the packet along a different path than configured on the router,
which can be used to bypass network security measures. This requirement
applies only to the forwarding of source-routerd traffic, such as when IPv4
forwarding is enabled and the system is functioning as a router.
Accepting source-routed packets in the IPv4 protocol has few legitimate uses. It should be disabled unless it is absolutely required. |
| CM-7(a) CM-7(b) CM-6(a) SC-7(a) |
Disable Kernel Parameter for Accepting ICMP Redirects by Default on IPv4 Interfaces |
To set the runtime status of the net.ipv4.conf.default.accept_redirects kernel parameter, run the following command: $ sudo sysctl -w net.ipv4.conf.default.accept_redirects=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv4.conf.default.accept_redirects = 0 |
ICMP redirect messages are used by routers to inform hosts that a more
direct route exists for a particular destination. These messages modify the
host's route table and are unauthenticated. An illicit ICMP redirect
message could result in a man-in-the-middle attack.
This feature of the IPv4 protocol has few legitimate uses. It should be disabled unless absolutely required. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add nodev Option to /var |
The nodev mount option can be used to prevent device files from
being created in /var.
Legitimate character and block devices should exist only in
the /dev directory on the root partition or within chroot
jails built for system services.
Add the nodev option to the fourth column of
/etc/fstab for the line which controls mounting of
/var.
|
The only legitimate location for device files is the /dev directory located on the root partition. The only exception to this is chroot jails. |
| CM-7(a) CM-7(b) CM-6(a) AC-6(1) |
Set Permissions on All Configuration Files Inside /etc/httpd/conf/ |
To properly set the permissions of /etc/http/conf/*, run the command: $ sudo chmod 0640 /etc/http/conf/* |
Access to the web server's configuration files may allow an unauthorized user or attacker to access information about the web server or to alter the server's configuration files. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable X Windows Startup By Setting Default Target |
Systems that do not require a graphical user interface should only boot by
default into multi-user.target mode. This prevents accidental booting of the system
into a graphical.target mode. Setting the system's default target to
multi-user.target will prevent automatic startup of the X server. To do so, run:
$ systemctl set-default multi-user.targetYou should see the following output: Removed symlink /etc/systemd/system/default.target. Created symlink from /etc/systemd/system/default.target to /usr/lib/systemd/system/multi-user.target. |
Services that are not required for system and application processes must not be active to decrease the attack surface of the system. X windows has a long history of security vulnerabilities and should not be used unless approved and documented. |
| SI-7 SI-7(1) CM-6(a) |
Configure AIDE to Verify Extended Attributes |
By default, the xattrs option is added to the FIPSR ruleset in AIDE.
If using a custom ruleset or the xattrs option is missing, add xattrs
to the appropriate ruleset.
For example, add xattrs to the following line in /etc/aide.conf:
FIPSR = p+i+n+u+g+s+m+c+acl+selinux+xattrs+sha256AIDE rules can be configured in multiple ways; this is merely one example that is already configured by default. The remediation provided with this rule adds xattrs to all rule sets available in /etc/aide.conf |
Extended attributes in file systems are used to contain arbitrary data and file metadata with security implications. |
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall httpd Package |
The httpd package can be removed with the following command:
$ sudo yum erase httpd |
If there is no need to make the web server software available, removing it provides a safeguard against its activation. |
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall tcpd Package |
The tcpd package can be removed with the following command:
$ sudo yum erase tcpd |
Administrators can use TCP wrapper library and daemon for host control over network services. In these implementations, xinetd runs tcpd program, which first looks at the incomming connection as well as the access control lists in the /etc/hosts.allow and /etc/hosts.deny files. Removing the xinetd package decreases the risk of the xinetd service's accidental (or intentional) activation. The removal of tcpd package will support this protective measure in addition. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add nodev Option to Non-Root Local Partitions |
The nodev mount option prevents files from being interpreted as
character or block devices. Legitimate character and block devices should
exist only in the /dev directory on the root partition or within
chroot jails built for system services.
Add the nodev option to the fourth column of
/etc/fstab for the line which controls mounting of
any non-root local partitions.
|
The nodev mount option prevents files from being interpreted as character or block devices. The only legitimate location for device files is the /dev directory located on the root partition. The only exception to this is chroot jails, for which it is not advised to set nodev on these filesystems. |
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall the telnet server | The telnet daemon should be uninstalled. | telnet allows clear text communications, and does not protect any data transmission between client and server. Any confidential data can be listened and no integrity checking is made.' |
| CM-7(a) CM-7(b) CM-6(a) |
Prevent Other Programs from Using Avahi's Port |
To prevent other mDNS stacks from running, edit /etc/avahi/avahi-daemon.conf
and ensure the following line appears in the [server] section:
disallow-other-stacks=yes |
This helps ensure that only Avahi is responsible for mDNS traffic coming from that port on the system. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable TIPC Support |
The Transparent Inter-Process Communication (TIPC) protocol
is designed to provide communications between nodes in a
cluster.
To configure the system to prevent the tipc
kernel module from being loaded, add the following line to the file /etc/modprobe.d/tipc.conf:
install tipc /bin/falseTo configure the system to prevent the tipc from being used,
add the following line to file /etc/modprobe.d/tipc.conf:
blacklist tipc |
Disabling TIPC protects the system against exploitation of any flaws in its implementation. |
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall openldap-servers Package | The openldap-servers package is not installed by default on a Red Hat Enterprise Linux 8 system. It is needed only by the OpenLDAP server, not by the clients which use LDAP for authentication. If the system is not intended for use as an LDAP Server it should be removed. | Unnecessary packages should not be installed to decrease the attack surface of the system. While this software is clearly essential on an LDAP server, it is not necessary on typical desktop or workstation systems. |
| AC-7 (a) | Configure the Use of the pam_faillock.so Module in the /etc/pam.d/password-auth File. | The pam_faillock.so module must be loaded in preauth in /etc/pam.d/password-auth. | If the pam_faillock.so module is not loaded the system will not correctly lockout accounts to prevent password guessing attacks. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable System Statistics Reset Service (sysstat) |
The sysstat service resets various I/O and CPU
performance statistics to zero in order to begin counting from a fresh state
at boot time.
The sysstat service can be disabled with the following command:
$ sudo systemctl mask --now sysstat.service |
By default the sysstat service runs a program at boot to reset performance statistics. This data can be retrieved using programs such as sar and sadc. While the sysstat service may provide useful insight into system operation, through the lens of providing only essential system services, this service should be disabled. |
| CM-7(a) CM-7(b) CM-6(a) IA-5(1)(c) |
Uninstall rsh-server Package |
The rsh-server package can be removed with the following command:
$ sudo yum erase rsh-server |
The rsh-server service provides unencrypted remote access service which does not provide for the confidentiality and integrity of user passwords or the remote session and has very weak authentication. If a privileged user were to login using this service, the privileged user password could be compromised. The rsh-server package provides several obsolete and insecure network services. Removing it decreases the risk of those services' accidental (or intentional) activation. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add nodev Option to /var/log/audit |
The nodev mount option can be used to prevent device files from
being created in /var/log/audit.
Legitimate character and block devices should exist only in
the /dev directory on the root partition or within chroot
jails built for system services.
Add the nodev option to the fourth column of
/etc/fstab for the line which controls mounting of
/var/log/audit.
|
The only legitimate location for device files is the /dev directory located on the root partition. The only exception to this is chroot jails. |
| AC-7(a) AU-7(1) AU-7(2) AU-14 AU-12(2) AU-2(a) CM-6(a) |
Ensure the audit Subsystem is Installed | The audit package should be installed. | The auditd service is an access monitoring and accounting daemon, watching system calls to audit any access, in comparison with potential local access control policy such as SELinux policy. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Kernel Parameter for Accepting ICMP Redirects by Default on IPv6 Interfaces |
To set the runtime status of the net.ipv6.conf.default.accept_redirects kernel parameter, run the following command: $ sudo sysctl -w net.ipv6.conf.default.accept_redirects=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv6.conf.default.accept_redirects = 0 |
An illicit ICMP redirect message could result in a man-in-the-middle attack. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Zeroconf Networking |
Zeroconf networking allows the system to assign itself an IP
address and engage in IP communication without a statically-assigned address or
even a DHCP server. Automatic address assignment via Zeroconf (or DHCP) is not
recommended. To disable Zeroconf automatic route assignment in the 169.254.0.0
subnet, add or correct the following line in /etc/sysconfig/network:
NOZEROCONF=yes |
Zeroconf addresses are in the network 169.254.0.0. The networking scripts add entries to the system's routing table for these addresses. Zeroconf address assignment commonly occurs when the system is configured to use DHCP but fails to receive an address assignment from the DHCP server. |
| CM-7(a) CM-7(b) CM-6(a) AC-6(1) |
Set Permissions on All Configuration Files Inside /etc/httpd/conf.modules.d/ |
To properly set the permissions of /etc/http/conf.modules.d/*, run the command: $ sudo chmod 0640 /etc/http/conf.modules.d/* |
Access to the web server's configuration files may allow an unauthorized user or attacker to access information about the web server or to alter the server's configuration files. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Support for RPC IPv6 |
RPC services for NFSv4 try to load transport modules for
udp6 and tcp6 by default, even if IPv6 has been disabled in
/etc/modprobe.d. To prevent RPC services such as rpc.mountd
from attempting to start IPv6 network listeners, remove or comment out the
following two lines in /etc/netconfig:
udp6 tpi_clts v inet6 udp - - tcp6 tpi_cots_ord v inet6 tcp - - |
|
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall DHCP Server Package |
If the system does not need to act as a DHCP server,
the dhcp package can be uninstalled.
The dhcp-server package can be removed with the following command:
$ sudo yum erase dhcp-server |
Removing the DHCP server ensures that it cannot be easily or accidentally reactivated and disrupt network operation. |
| CM-7(a) CM-7(b) CM-6(a) IA-5(1)(c) |
Disable ypbind Service |
The ypbind service, which allows the system to act as a client in
a NIS or NIS+ domain, should be disabled.
The ypbind service can be disabled with the following command:
$ sudo systemctl mask --now ypbind.service |
Disabling the ypbind service ensures the system is not acting as a client in a NIS or NIS+ domain. This service should be disabled unless in use. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Print Server Capabilities |
To prevent remote users from potentially connecting to and using
locally configured printers, disable the CUPS print server sharing
capabilities. To do so, limit how the server will listen for print jobs by
removing the more generic port directive from /etc/cups/cupsd.conf:
Port 631and replacing it with the Listen directive: Listen localhost:631This will prevent remote users from printing to locally configured printers while still allowing local users on the system to print normally. |
By default, locally configured printers will not be shared over the network, but if this functionality has somehow been enabled, these recommendations will disable it again. Be sure to disable outgoing printer list broadcasts, or remote users will still be able to see the locally configured printers, even if they cannot actually print to them. To limit print serving to a particular set of users, use the Policy directive. |
| CM-7(a) CM-7(b) SC-5 CM-6(a) SC-7(a) |
Disable Kernel Parameter for Sending ICMP Redirects on all IPv4 Interfaces |
To set the runtime status of the net.ipv4.conf.all.send_redirects kernel parameter, run the following command: $ sudo sysctl -w net.ipv4.conf.all.send_redirects=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv4.conf.all.send_redirects = 0 |
ICMP redirect messages are used by routers to inform hosts that a more
direct route exists for a particular destination. These messages contain information
from the system's route table possibly revealing portions of the network topology.
The ability to send ICMP redirects is only appropriate for systems acting as routers. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add noexec Option to /var/log |
The noexec mount option can be used to prevent binaries
from being executed out of /var/log.
Add the noexec option to the fourth column of
/etc/fstab for the line which controls mounting of
/var/log.
|
Allowing users to execute binaries from directories containing log files such as /var/log should never be necessary in normal operation and can expose the system to potential compromise. |
| CM-7(a) CM-6(a) |
Disable Automatic Bug Reporting Tool (abrtd) |
The Automatic Bug Reporting Tool (abrtd) daemon collects
and reports crash data when an application crash is detected. Using a variety
of plugins, abrtd can email crash reports to system administrators, log crash
reports to files, or forward crash reports to a centralized issue tracking
system such as RHTSupport.
The abrtd service can be disabled with the following command:
$ sudo systemctl mask --now abrtd.service |
Mishandling crash data could expose sensitive information about vulnerabilities in software executing on the system, as well as sensitive information from within a process's address space or registers. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Mounting of hfs |
To configure the system to prevent the hfs
kernel module from being loaded, add the following line to the file /etc/modprobe.d/hfs.conf:
install hfs /bin/falseTo configure the system to prevent the hfs from being used,
add the following line to file /etc/modprobe.d/hfs.conf:
blacklist hfsThis effectively prevents usage of this uncommon filesystem. |
Linux kernel modules which implement filesystems that are not needed by the local system should be disabled. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Mounting of freevxfs |
To configure the system to prevent the freevxfs
kernel module from being loaded, add the following line to the file /etc/modprobe.d/freevxfs.conf:
install freevxfs /bin/falseTo configure the system to prevent the freevxfs from being used,
add the following line to file /etc/modprobe.d/freevxfs.conf:
blacklist freevxfsThis effectively prevents usage of this uncommon filesystem. |
Linux kernel modules which implement filesystems that are not needed by the local system should be disabled. |
| CM-7(a) CM-7(b) SC-5(3)(a) |
Enable Kernel Parameter to Log Martian Packets on all IPv4 Interfaces |
To set the runtime status of the net.ipv4.conf.all.log_martians kernel parameter, run the following command: $ sudo sysctl -w net.ipv4.conf.all.log_martians=1To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv4.conf.all.log_martians = 1 |
The presence of "martian" packets (which have impossible addresses) as well as spoofed packets, source-routed packets, and redirects could be a sign of nefarious network activity. Logging these packets enables this activity to be detected. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Network Console (netconsole) |
The netconsole service is responsible for loading the
netconsole kernel module, which logs kernel printk messages over UDP to a
syslog server. This allows debugging of problems where disk logging fails and
serial consoles are impractical.
The netconsole service can be disabled with the following command:
$ sudo systemctl mask --now netconsole.service |
The netconsole service is not necessary unless there is a need to debug kernel panics, which is not common. |
| CM-7(a) CM-7(b) CM-6(a) IA-5(1)(c) |
Uninstall ypserv Package |
The ypserv package can be removed with the following command:
$ sudo yum erase ypserv |
The NIS service provides an unencrypted authentication service which does not provide for the confidentiality and integrity of user passwords or the remote session. Removing the ypserv package decreases the risk of the accidental (or intentional) activation of NIS or NIS+ services. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Advanced Configuration and Power Interface (acpid) |
The Advanced Configuration and Power Interface Daemon (acpid)
dispatches ACPI events (such as power/reset button depressed) to userspace
programs.
The acpid service can be disabled with the following command:
$ sudo systemctl mask --now acpid.service |
ACPI support is highly desirable for systems in some network roles, such as laptops or desktops. For other systems, such as servers, it may permit accidental or trivially achievable denial of service situations and disabling it is appropriate. |
| CM-7(a) CM-7(b) CM-6(a) |
Uninstall DHCP Client Package |
If the system does not need to act as a DHCP client,
the dhcp-client package can be uninstalled.
The dhcp-client package can be removed with the following command:
$ sudo yum erase dhcp-client |
Removing the DHCP client is necessary when the system works or will work in a static network environment. In this case the system has/will have a static IP address assigned. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable DCCP Support |
The Datagram Congestion Control Protocol (DCCP) is a
relatively new transport layer protocol, designed to support
streaming media and telephony.
To configure the system to prevent the dccp
kernel module from being loaded, add the following line to the file /etc/modprobe.d/dccp.conf:
install dccp /bin/falseTo configure the system to prevent the dccp from being used,
add the following line to file /etc/modprobe.d/dccp.conf:
blacklist dccp |
Disabling DCCP protects the system against exploitation of any flaws in its implementation. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add noexec Option to Removable Media Partitions |
The noexec mount option prevents the direct execution of binaries
on the mounted filesystem. Preventing the direct execution of binaries from
removable media (such as a USB key) provides a defense against malicious
software that may be present on such untrusted media.
Add the noexec option to the fourth column of
/etc/fstab for the line which controls mounting of
any removable media partitions.
|
Allowing users to execute binaries from removable media such as USB keys exposes the system to potential compromise. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Software RAID Monitor (mdmonitor) |
The mdmonitor service is used for monitoring a software RAID array; hardware
RAID setups do not use this service.
The mdmonitor service can be disabled with the following command:
$ sudo systemctl mask --now mdmonitor.service |
If software RAID monitoring is not required, there is no need to run this service. |
| CM-7(a) CM-7(b) CM-6(a) IA-2 IA-2(8) IA-2(9) AC-17(a) |
Use Kerberos Security on All Exports | Using Kerberos on all exported mounts prevents a malicious client or user from impersonating a system user. To cryptography authenticate users to the NFS server, add sec=krb5:krb5i:krb5p to each export in /etc/exports. | When an NFS server is configured to use AUTH_SYS a selected userid and groupid are used to handle requests from the remote user. The userid and groupid could mistakenly or maliciously be set incorrectly. The AUTH_GSS method of authentication uses certificates on the server and client systems to more securely authenticate the remote mount request. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable SCTP Support |
The Stream Control Transmission Protocol (SCTP) is a
transport layer protocol, designed to support the idea of
message-oriented communication, with several streams of messages
within one connection.
To configure the system to prevent the sctp
kernel module from being loaded, add the following line to the file /etc/modprobe.d/sctp.conf:
install sctp /bin/falseTo configure the system to prevent the sctp from being used,
add the following line to file /etc/modprobe.d/sctp.conf:
blacklist sctp |
Disabling SCTP protects the system against exploitation of any flaws in its implementation. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Bind Mount /var/tmp To /tmp |
The /var/tmp directory is a world-writable directory. Bind-mount
it to /tmp in order to consolidate temporary storage into one
location protected by the same techniques as /tmp. To do so, edit
/etc/fstab and add the following line:
/tmp /var/tmp none rw,nodev,noexec,nosuid,bind 0 0See the mount(8) man page for further explanation of bind mounting. |
Having multiple locations for temporary storage is not required. Unless absolutely necessary to meet requirements, the storage location /var/tmp should be bind mounted to /tmp and thus share the same protections. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable Mounting of squashfs |
To configure the system to prevent the squashfs
kernel module from being loaded, add the following line to the file /etc/modprobe.d/squashfs.conf:
install squashfs /bin/falseTo configure the system to prevent the squashfs from being used,
add the following line to file /etc/modprobe.d/squashfs.conf:
blacklist squashfsThis effectively prevents usage of this uncommon filesystem. The squashfs filesystem type is a compressed read-only Linux filesystem embedded in small footprint systems (similar to cramfs). A squashfs image can be used without having to first decompress the image. |
Removing support for unneeded filesystem types reduces the local attack surface of the system. |
| CM-7(a) CM-7(b) CM-6(a) |
Disable httpd Service |
The httpd service can be disabled with the following command:
$ sudo systemctl mask --now httpd.service |
Running web server software provides a network-based avenue of attack, and should be disabled if not needed. |
| CM-7(a) CM-7(b) CM-6(a) IA-2 |
Disable GDM Guest Login |
The GNOME Display Manager (GDM) can allow users to login without credentials
which can be useful for public kiosk scenarios. Allowing users to login without credentials
or "guest" account access has inherent security risks and should be disabled. To do disable
timed logins or guest account access, set the TimedLoginEnable to false in
the [daemon] section in /etc/gdm/custom.conf. For example:
[daemon] TimedLoginEnable=false |
Failure to restrict system access to authenticated users negatively impacts operating system security. |
| CM-7(a) CM-7(b) CM-6(a) |
Set httpd ServerSignature Directive to Off |
ServerSignature Off restricts httpd from displaying server version number
on error pages.
Add or correct the following directive in /etc/httpd/conf/httpd.conf: ServerSignature Off |
Information disclosed to clients about the configuration of the web server and system could be used to plan an attack on the given system. This information disclosure should be restricted to a minimum. |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
Add nodev Option to Removable Media Partitions |
The nodev mount option prevents files from being
interpreted as character or block devices.
Legitimate character and block devices should exist only in
the /dev directory on the root partition or within chroot
jails built for system services.
Add the nodev option to the fourth column of
/etc/fstab for the line which controls mounting of
any removable media partitions.
|
The only legitimate location for device files is the /dev directory located on the root partition. An exception to this is chroot jails, and it is not advised to set nodev on partitions which contain their root filesystems. |
| CM-7(a) CM-7(b) CM-6(a) |
Minimize Served Information |
Edit /etc/dhcp/dhcpd.conf. Examine each address range section within
the file, and ensure that the following options are not defined unless there is
an operational need to provide this information via DHCP:
option domain-name option domain-name-servers option nis-domain option nis-servers option ntp-servers option routers option time-offset |
Because the configuration information provided by the DHCP server could be maliciously provided to clients by a rogue DHCP server, the amount of information provided via DHCP should be minimized. Remove these definitions from the DHCP server configuration to ensure that legitimate clients do not unnecessarily rely on DHCP for this information. |
| AC-7 (a) | An SELinux Context must be configured for the pam_faillock.so records directory | The dir configuration option in PAM pam_faillock.so module defines where the lockout records is stored. The configured directory must have the correct SELinux context. | Not having the correct SELinux context on the pam_faillock.so records directory may lead to unauthorized access to the directory. |
| CM-7(a) CM-7(b) SC-5 |
Enable Kernel Parameter to Ignore Bogus ICMP Error Responses on IPv4 Interfaces |
To set the runtime status of the net.ipv4.icmp_ignore_bogus_error_responses kernel parameter, run the following command: $ sudo sysctl -w net.ipv4.icmp_ignore_bogus_error_responses=1To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: net.ipv4.icmp_ignore_bogus_error_responses = 1 |
Ignoring bogus ICMP error responses reduces log size, although some activity would not be logged. |
| CM-7(1) | Disable network management of chrony daemon | The cmdport option in /etc/chrony.conf can be set to 0 to stop chrony daemon from listening on the UDP port 323 for management connections made by chronyc. | Minimizing the exposure of the server functionality of the chrony daemon diminishes the attack surface. |
| SC-7(10) | Disable acquiring, saving, and processing core dumps | The systemd-coredump.socket unit is a socket activation of the systemd-coredump@.service which processes core dumps. By masking the unit, core dump processing is disabled. | A core dump includes a memory image taken at the time the operating system terminates an application. The memory image could contain sensitive data and is generally useful only for developers trying to debug problems. |
| SC-7(10) | Restrict usage of ptrace to descendant processes |
To set the runtime status of the kernel.yama.ptrace_scope kernel parameter, run the following command: $ sudo sysctl -w kernel.yama.ptrace_scope=1To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: kernel.yama.ptrace_scope = 1 |
Unrestricted usage of ptrace allows compromised binaries to run ptrace on another processes of the user. Like this, the attacker can steal sensitive information from the target processes (e.g. SSH sessions, web browser, ...) without any additional assistance from the user (i.e. without resorting to phishing). |
| SC-7(10) | Disable storing core dumps |
To set the runtime status of the kernel.core_pattern kernel parameter, run the following command: $ sudo sysctl -w kernel.core_pattern=|/bin/falseTo make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: kernel.core_pattern = |/bin/false |
A core dump includes a memory image taken at the time the operating system terminates an application. The memory image could contain sensitive data and is generally useful only for developers trying to debug problems. |
| AC-8(a) AC-8(c) AC-17(a) CM-6(a) |
Enable SSH Warning Banner |
To enable the warning banner and ensure it is consistent
across the system, add or correct the following line in
/etc/ssh/sshd_config:
Banner /etc/issue.netAnother section contains information on how to create an appropriate system-wide warning banner. |
The warning message reinforces policy awareness during the logon process and facilitates possible legal action against attackers. Alternatively, systems whose ownership should not be obvious should ensure usage of a banner that does not provide easy attribution. |
| AC-8(a) AC-8(b) AC-8(c) |
Enable GNOME3 Login Warning Banner |
In the default graphical environment, displaying a login warning banner
in the GNOME Display Manager's login screen can be enabled on the login
screen by setting banner-message-enable to true.
To enable, add or edit banner-message-enable to /etc/dconf/db/gdm.d/00-security-settings. For example: [org/gnome/login-screen] banner-message-enable=trueOnce the setting has been added, add a lock to /etc/dconf/db/gdm.d/locks/00-security-settings-lock to prevent user modification. For example: /org/gnome/login-screen/banner-message-enableAfter the settings have been set, run dconf update. The banner text must also be set. |
Display of a standardized and approved use notification before granting access to the operating system
ensures privacy and security notification verbiage used is consistent with applicable federal laws,
Executive Orders, directives, policies, regulations, standards, and guidance.
For U.S. Government systems, system use notifications are required only for access via login interfaces with human users and are not required when such human interfaces do not exist. |
| AC-8(a) AC-8(c) |
Modify the System Login Banner |
To configure the system login banner edit /etc/issue. Replace the
default text with a message compliant with the local site policy or a legal
disclaimer.
The DoD required text is either:
You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only. By using this IS (which includes any device attached to this IS), you consent to the following conditions: -The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations. -At any time, the USG may inspect and seize data stored on this IS. -Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose. -This IS includes security measures (e.g., authentication and access controls) to protect USG interests -- not for your personal benefit or privacy. -Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details. OR: I've read & consent to terms in IS user agreem't. |
Display of a standardized and approved use notification before granting
access to the operating system ensures privacy and security notification
verbiage used is consistent with applicable federal laws, Executive Orders,
directives, policies, regulations, standards, and guidance.
System use notifications are required only for access via login interfaces with human users and are not required when such human interfaces do not exist. |
| AC-8(a) AC-8(c) |
Configure SMTP Greeting Banner |
Edit /etc/postfix/main.cf, and add or correct the
following line, substituting some other wording for the banner information if
you prefer:
smtpd_banner = $myhostname ESMTP |
The default greeting banner discloses that the listening mail process is Postfix. When remote mail senders connect to the MTA on port 25, they are greeted by an initial banner as part of the SMTP dialogue. This banner is necessary, but it frequently gives away too much information, including the MTA software which is in use, and sometimes also its version number. Remote mail senders do not need this information in order to send mail, so the banner should be changed to reveal only the hostname (which is already known and may be useful) and the word ESMTP, to indicate that the modern SMTP protocol variant is supported. |
| AC-8 a AC-8.1 (ii) AC-8 b AC-8.1 (iii) |
Display the Standard Mandatory DoD Notice and Consent Banner until Explicit Acknowledgement |
Display of a standardized and approved use notification before granting access to the SUSE operating system ensures privacy and security notification verbiage used is consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance. The banner must be acknowledged by the user prior to allowing the user access to the SUSE operating system. This provides assurance that the user has seen the message and accepted the conditions for access. If the consent banner is not acknowledged by the user, DoD will not be in compliance with system use notifications required by law. System use notifications are required only for access via logon interfaces with human users and are not required when such human interfaces do not exist. The banner must be formatted in accordance with applicable DoD policy. Use the following verbiage for the SUSE operating system: You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only. By using this IS (which includes any device attached to this IS), you consent to the following conditions: -The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations. -At any time, the USG may inspect and seize data stored on this IS. -Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose. -This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy. -Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details.Check the configuration by running the following command: # more /etc/gdm/XsessionThe beginning of the file must contain the following text immediately after #!/bin/sh: if ! zenity --text-info \ --title "Consent" \ --filename=/etc/gdm/banner \ --no-markup \ --checkbox="Accept." 10 10; then sleep 1; exit 1; fi |
Display of a standardized and approved use notification before granting access to the operating system
ensures privacy and security notification verbiage used is consistent with applicable federal laws,
Executive Orders, directives, policies, regulations, standards, and guidance.
For U.S. Government systems, system use notifications are required only for access via login interfaces with human users and are not required when such human interfaces do not exist. |
| AC-8(a) AC-8(c) |
Set the GNOME3 Login Warning Banner Text |
In the default graphical environment, configuring the login warning banner text
in the GNOME Display Manager's login screen can be configured on the login
screen by setting banner-message-text to 'APPROVED_BANNER'
where APPROVED_BANNER is the approved banner for your environment.
To enable, add or edit banner-message-text to /etc/dconf/db/gdm.d/00-security-settings. For example: [org/gnome/login-screen] banner-message-text='APPROVED_BANNER'Once the setting has been added, add a lock to /etc/dconf/db/gdm.d/locks/00-security-settings-lock to prevent user modification. For example: /org/gnome/login-screen/banner-message-textAfter the settings have been set, run dconf update. When entering a warning banner that spans several lines, remember to begin and end the string with ' and use \n for new lines. |
An appropriate warning message reinforces policy awareness during the logon process and facilitates possible legal action against attackers. |
| AC-8(a) AC-8(c) AC-17(a) CM-6(a) |
Enable SSH Warning Banner |
To enable the warning banner and ensure it is consistent
across the system, add or correct the following line in
/etc/ssh/sshd_config:
Banner /etc/issueAnother section contains information on how to create an appropriate system-wide warning banner. |
The warning message reinforces policy awareness during the logon process and facilitates possible legal action against attackers. Alternatively, systems whose ownership should not be obvious should ensure usage of a banner that does not provide easy attribution. |
| AC-8(b) | Modify the System GUI Login Banner |
To configure the GUI system login banner edit /etc/gdm/banner.
Replace the default text with a message compliant with the local site
policy or a legal disclaimer.
The DoD required text is either:
You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only. By using this IS (which includes any device attached to this IS), you consent to the following conditions: -The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations. -At any time, the USG may inspect and seize data stored on this IS. -Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose. -This IS includes security measures (e.g., authentication and access controls) to protect USG interests -- not for your personal benefit or privacy. -Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details. OR: I've read & consent to terms in IS user agreem't. |
Display of a standardized and approved use notification before granting
access to the operating system ensures privacy and security notification
verbiage used is consistent with applicable federal laws, Executive Orders,
directives, policies, regulations, standards, and guidance.
System use notifications are required only for access via login interfaces with human users and are not required when such human interfaces do not exist. |
| SC-8(1) SC-13 |
Harden OpenSSL Crypto Policy | Crypto Policies are means of enforcing certain cryptographic settings for selected applications including OpenSSL. OpenSSL is by default configured to modify its configuration based on currently configured Crypto Policy. However, in certain cases it might be needed to override the Crypto Policy specific to OpenSSL and leave rest of the Crypto Policy intact. This can be done by dropping a file named opensslcnf-xxx.config, replacing xxx with arbitrary identifier, into /etc/crypto-policies/local.d. This has to be followed by running update-crypto-policies so that changes are applied. Changes are propagated into /etc/crypto-policies/back-ends/opensslcnf.config. This rule checks if this file contains predefined Ciphersuites variable configured with predefined value. | The Common Criteria requirements specify that certain parameters for OpenSSL are configured e.g. cipher suites. Currently particular requirements specified by CC are stricter compared to any existing Crypto Policy. |
| AU-8(1) AU-12(1) |
Disable chrony daemon from acting as server | The port option in /etc/chrony.conf can be set to 0 to make chrony daemon to never open any listening port for server operation and to operate strictly in a client-only mode. | In order to prevent unauthorized connection of devices, unauthorized transfer of information, or unauthorized tunneling (i.e., embedding of data types within data types), organizations must disable or restrict unused or unnecessary physical and logical ports/protocols on information systems. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services provided by default may not be necessary to support essential organizational operations. Additionally, it is sometimes convenient to provide multiple services from a single component (e.g., VPN and IPS); however, doing so increases risk over limiting the services provided by any one component. To support the requirements and principles of least functionality, the operating system must support the organizational requirements, providing only essential capabilities and limiting the use of ports, protocols, and/or services to only those required, authorized, and approved to conduct official business or to address authorized quality of life issues. |
| CM-8(3) IA-3 |
Install usbguard Package |
The usbguard package can be installed with the following command:
$ sudo yum install usbguard |
usbguard is a software framework that helps to protect against rogue USB devices by implementing basic whitelisting/blacklisting capabilities based on USB device attributes. |
| CM-8(3)(a) IA-3 |
Enable the USBGuard Service |
The USBGuard service should be enabled.
The usbguard service can be enabled with the following command:
$ sudo systemctl enable usbguard.service |
The usbguard service must be running in order to enforce the USB device authorization policy for all USB devices. |
| CM-8(3)(a) IA-3 |
Generate USBGuard Policy | By default USBGuard when enabled prevents access to all USB devices and this lead to inaccessible system if they use USB mouse/keyboard. To prevent this scenario, the initial policy configuration must be generated based on current connected USB devices. | The usbguard must be configured to allow connected USB devices to work properly, avoiding the system to become inaccessible. |
| CM-8(3) IA-3 |
Authorize Human Interface Devices and USB hubs in USBGuard daemon | To allow authorization of USB devices combining human interface device and hub capabilities by USBGuard daemon, add the line allow with-interface match-all { 03:*:* 09:00:* } to /etc/usbguard/rules.conf. | Without allowing Human Interface Devices, it might not be possible to interact with the system. Without allowing hubs, it might not be possible to use any USB devices on the system. |
| AU-9 | Audit Tools Must Have a Mode of 0755 or Less Permissive | Red Hat Enterprise Linux 8 systems providing tools to interface with audit information will leverage user permissions and roles identifying the user accessing the tools, and the corresponding rights the user enjoys, to make access decisions regarding the access to audit tools. Audit tools include, but are not limited to, vendor-provided and open source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators. Audit tools must have a mode of 0755 or less permissive. | Protecting audit information also includes identifying and protecting the tools used to view and manipulate log data. Therefore, protecting audit tools is necessary to prevent unauthorized operations on audit information. |
| AU-9 | Audit Tools Must Be Owned by Root | Red Hat Enterprise Linux 8 systems providing tools to interface with audit information will leverage user permissions and roles identifying the user accessing the tools, and the corresponding rights the user enjoys, to make access decisions regarding the access to audit tools. Audit tools include, but are not limited to, vendor-provided and open source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators. Audit tools must have the correct owner. | Protecting audit information also includes identifying and protecting the tools used to view and manipulate log data. Therefore, protecting audit tools is necessary to prevent unauthorized operations on audit information. |
| AU-9 | Audit Tools Must Be Group-owned by Root | Red Hat Enterprise Linux 8 systems providing tools to interface with audit information will leverage user permissions and roles identifying the user accessing the tools, and the corresponding rights the user enjoys, to make access decisions regarding the access to audit tools. Audit tools include, but are not limited to, vendor-provided and open source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators. Audit tools must have the correct group owner. | Protecting audit information also includes identifying and protecting the tools used to view and manipulate log data. Therefore, protecting audit tools is necessary to prevent unauthorized operations on audit information. |
| AU-9 | Verify that Local Logs of the audit Daemon are not World-Readable |
Files containing sensitive informations should be protected by restrictive
permissions. Most of the time, there is no need that these files need to be
read by any non-root user.
Check that "permissions.local" file contains the correct permissions rules with the following command:
# grep -i audit /etc/permissions.local /var/log/audit/ root:root 600 /var/log/audit/audit.log root:root 600 /etc/audit/audit.rules root:root 640 /etc/audit/rules.d/audit.rules root:root 640 |
Without the capability to restrict which roles and individuals can select which events are audited, unauthorized personnel may be able to prevent the auditing of critical events. Misconfigured audits may degrade the system's performance by overwhelming the audit log. Misconfigured audits may also make it more difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. |
| AC-9 AC-9(1) |
Ensure PAM Displays Last Logon/Access Notification |
To configure the system to notify users of last logon/access using pam_lastlog,
add or correct the pam_lastlog settings in /etc/pam.d/postlogin
to include showfailed option, such as:
session [default=1] pam_lastlog.so showfailedAnd make sure that the silent option is not set for this specific line. |
Users need to be aware of activity that occurs regarding their account. Providing users with information regarding the number of unsuccessful attempts that were made to login to their account allows the user to determine if any unauthorized activity has occurred and gives them an opportunity to notify administrators. |
| AC-9 AC-9(1) |
Enable SSH Print Last Log |
Ensure that SSH will display the date and time of the last successful account logon.
The default SSH configuration enables print of the date and time of the last login. The appropriate configuration is used if no value is set for PrintLastLog. To explicitly enable LastLog in SSH, add or correct the following line in /etc/ssh/sshd_config: PrintLastLog yes |
Providing users feedback on when account accesses last occurred facilitates user recognition and reporting of unauthorized account use. |
| AU-9(3) CM-6(a) |
Encrypt Audit Records Sent With audispd Plugin |
Configure the operating system to encrypt the transfer of off-loaded audit
records onto a different system or media from the system being audited.
Set the transport option in /etc/audit/audisp-remote.confto KRB5. |
Information stored in one location is vulnerable to accidental or incidental deletion or alteration. Off-loading is a common process in information systems with limited audit storage capacity. |
| AU-9(3) CM-6(a) |
Configure TLS for rsyslog remote logging |
Configure rsyslog to use Transport Layer
Security (TLS) support for logging to remote server
for the Forwarding Output Module in /etc/rsyslog.conf
using action. You can use the following command:
echo 'action(type="omfwd" protocol="tcp" Target="<remote system>" port="6514"
StreamDriver="gtls" StreamDriverMode="1" StreamDriverAuthMode="x509/name" streamdriver.CheckExtendedKeyPurpose="on")' >> /etc/rsyslog.conf
Replace the <remote system> in the above command with an IP address or a host name of the remote logging server.
|
For protection of data being logged, the connection to the remote logging server needs to be authenticated and encrypted. |
| AU-9(3) AU-9(3).1 |
Configure AIDE to Verify the Audit Tools | The operating system file integrity tool must be configured to protect the integrity of the audit tools. | Protecting the integrity of the tools used for auditing purposes is a critical step toward ensuring the integrity of audit information. Audit information includes all information (e.g., audit records, audit settings, and audit reports) needed to successfully audit information system activity. Audit tools include but are not limited to vendor-provided and open-source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators. It is not uncommon for attackers to replace the audit tools or inject code into the existing tools to provide the capability to hide or erase system activity from the audit logs. To address this risk, audit tools must be cryptographically signed to provide the capability to identify when the audit tools have been modified, manipulated, or replaced. An example is a checksum hash of the file or files. |
| AC-10 CM-6(a) |
Limit the Number of Concurrent Login Sessions Allowed Per User |
Limiting the number of allowed users and sessions per user can limit risks related to Denial of
Service attacks. This addresses concurrent sessions for a single account and does not address
concurrent sessions by a single user via multiple accounts. To set the number of concurrent
sessions per user add the following line in /etc/security/limits.conf or
a file under /etc/security/limits.d/:
* hard maxlogins 1 |
Limiting simultaneous user logins can insulate the system from denial of service problems caused by excessive logins. Automated login processes operating improperly or maliciously may result in an exceptional number of simultaneous login sessions. |
| AC-11(a) CM-6(a) |
Set GNOME3 Screensaver Inactivity Timeout |
The idle time-out value for inactivity in the GNOME3 desktop is configured via the idle-delay
setting must be set under an appropriate configuration file(s) in the /etc/dconf/db/local.d directory
and locked in /etc/dconf/db/local.d/locks directory to prevent user modification.
For example, to configure the system for a 15 minute delay, add the following to /etc/dconf/db/local.d/00-security-settings: [org/gnome/desktop/session] idle-delay=uint32 900 |
A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not logout because of the temporary nature of the absence. Rather than relying on the user to manually lock their operating system session prior to vacating the vicinity, GNOME3 can be configured to identify when a user's session has idled and take action to initiate a session lock. |
| SI-11(a) SI-11(b) |
Restrict Access to Kernel Message Buffer |
To set the runtime status of the kernel.dmesg_restrict kernel parameter, run the following command: $ sudo sysctl -w kernel.dmesg_restrict=1To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: kernel.dmesg_restrict = 1 |
Unprivileged access to the kernel syslog can expose sensitive kernel address information. |
| IA-11 CM-6(a) |
Ensure Users Re-Authenticate for Privilege Escalation - sudo | The sudo NOPASSWD and !authenticate option, when specified, allows a user to execute commands using sudo without having to authenticate. This should be disabled by making sure that NOPASSWD and/or !authenticate do not exist in /etc/sudoers configuration file or any sudo configuration snippets in /etc/sudoers.d/." |
Without re-authentication, users may access resources or perform tasks for which they
do not have authorization.
When operating systems provide the capability to escalate a functional capability, it is critical that the user re-authenticate. |
| SI-11(b) SI-11(c) SI-11.1(iv) |
Verify Permissions on lastlog Command |
To properly set the permissions of /usr/bin/lastlog, run the command:
$ sudo chmod 0750 /usr/bin/lastlog |
Unauthorized disclosure of the contents of the /var/log/lastlog file can reveal system data to attackers, thus compromising its confidentiality. |
| SI-11(b) SI-11(c) SI-11.1(iv) |
Verify Group Who Owns lastlog Command |
To properly set the group owner of /var/log/lastlog, run the command:
$ sudo chgrp root /var/log/lastlog |
Unauthorized disclosure of the contents of the /var/log/lastlog file can reveal system data to attackers, thus compromising its confidentiality. |
| SI-11(a) SI-11(b) SI-11.1(iii) |
Verify permissions of log files | Any operating system providing too much information in error messages risks compromising the data and security of the structure, and content of error messages needs to be carefully considered by the organization. Organizations carefully consider the structure/content of error messages. The extent to which information systems are able to identify and handle error conditions is guided by organizational policy and operational requirements. Information that could be exploited by adversaries includes, for example, erroneous logon attempts with passwords entered by mistake as the username, mission/business information that can be derived from (if not stated explicitly by) information recorded, and personal information, such as account numbers, social security numbers, and credit card numbers. | The Red Hat Enterprise Linux 8 must generate error messages that provide information necessary for corrective actions without revealing information that could be exploited by adversaries. |
| AC-11(a) CM-6(a) |
Set GNOME3 Screensaver Lock Delay After Activation Period |
To activate the locking delay of the screensaver in the GNOME3 desktop when
the screensaver is activated, add or set lock-delay to uint32 0 in
/etc/dconf/db/local.d/00-security-settings. For example:
[org/gnome/desktop/screensaver] lock-delay=uint32 0After the settings have been set, run dconf update. |
A session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not want to logout because of the temporary nature of the absense. |
| IA-11 | Require Re-Authentication When Using the sudo Command | The sudo timestamp_timeout tag sets the amount of time sudo password prompt waits. The default timestamp_timeout value is 5 minutes. The timestamp_timeout should be configured by making sure that the timestamp_timeout tag exists in /etc/sudoers configuration file or any sudo configuration snippets in /etc/sudoers.d/. If the value is set to an integer less than 0, the user's time stamp will not expire and the user will not have to re-authenticate for privileged actions until the user's session is terminated. |
Without re-authentication, users may access resources or perform tasks for which they
do not have authorization.
When operating systems provide the capability to escalate a functional capability, it is critical that the user re-authenticate. |
| IA-11 | Disallow Configuration to Bypass Password Requirements for Privilege Escalation |
Verify the operating system is not configured to bypass password requirements for privilege
escalation. Check the configuration of the "/etc/pam.d/sudo" file with the following command:
$ sudo grep pam_succeed_if /etc/pam.d/sudoIf any occurrences of "pam_succeed_if" is returned from the command, this is a finding. |
Without re-authentication, users may access resources or perform tasks for which they do not have authorization. When operating systems provide the capability to escalate a functional capability, it is critical the user re-authenticate. |
| AC-11(a) AC-11(b) CM-6(a) |
Configure the tmux Lock Command |
To enable console screen locking in tmux terminal multiplexer,
the vlock command must be configured to be used as a locking
mechanism.
Add the following line to /etc/tmux.conf:
set -g lock-command vlock. The console can now be locked with the following key combination: ctrl+b :lock-session |
The tmux package allows for a session lock to be implemented and configured. However, the session lock is implemented by an external command. The tmux default configuration does not contain an effective session lock. |
| CM-11(a) CM-11(b) CM-6(a) CM-5(3) SA-12 SA-12(10) |
Ensure gpgcheck Enabled for Local Packages | yum should be configured to verify the signature(s) of local packages prior to installation. To configure yum to verify signatures of local packages, set the localpkg_gpgcheck to 1 in /etc/yum.conf. |
Changes to any software components can have significant effects to the overall security
of the operating system. This requirement ensures the software has not been tampered and
has been provided by a trusted vendor.
Accordingly, patches, service packs, device drivers, or operating system components must be signed with a certificate recognized and approved by the organization. |
| AU-11 CM-6(a) |
Configure auditd Max Log File Size |
Determine the amount of audit data (in megabytes)
which should be retained in each log file. Edit the file
/etc/audit/auditd.conf. Add or modify the following line, substituting
the correct value of 6 for STOREMB:
max_log_file = STOREMBSet the value to 6 (MB) or higher for general-purpose systems. Larger values, of course, support retention of even more audit data. |
The total storage for audit log files must be large enough to retain log information over the period required. This is a function of the maximum log file size and the number of logs retained. |
| SI-11(b) SI-11(c) SI-11.1(iv) |
Verify Owner on lastlog Command |
To properly set the owner of /usr/bin/lastlog, run the command:
$ sudo chown root /usr/bin/lastlog |
Unauthorized disclosure of the contents of the /var/log/lastlog file can reveal system data to attackers, thus compromising its confidentiality. |
| AU-11 CM-6(a) |
Configure auditd Number of Logs Retained |
Determine how many log files
auditd should retain when it rotates logs.
Edit the file /etc/audit/auditd.conf. Add or modify the following
line, substituting NUMLOGS with the correct value of 5:
num_logs = NUMLOGSSet the value to 5 for general-purpose systems. Note that values less than 2 result in no log rotation. |
The total storage for audit log files must be large enough to retain log information over the period required. This is a function of the maximum log file size and the number of logs retained. |
| IA-11 CM-6(a) |
Ensure Users Re-Authenticate for Privilege Escalation - sudo !authenticate | The sudo !authenticate option, when specified, allows a user to execute commands using sudo without having to authenticate. This should be disabled by making sure that the !authenticate option does not exist in /etc/sudoers configuration file or any sudo configuration snippets in /etc/sudoers.d/. |
Without re-authentication, users may access resources or perform tasks for which they
do not have authorization.
When operating systems provide the capability to escalate a functional capability, it is critical that the user re-authenticate. |
| SI-11(a) SI-11(b) |
Disable Core Dumps for SUID programs |
To set the runtime status of the fs.suid_dumpable kernel parameter, run the following command: $ sudo sysctl -w fs.suid_dumpable=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: fs.suid_dumpable = 0 |
The core dump of a setuid program is more likely to contain sensitive data, as the program itself runs with greater privileges than the user who initiated execution of the program. Disabling the ability for any setuid program to write a core file decreases the risk of unauthorized access of such data. |
| AU-11 CM-6(a) |
Configure auditd flush priority |
The auditd service can be configured to
synchronously write audit event data to disk. Add or correct the following
line in /etc/audit/auditd.conf to ensure that audit event data is
fully synchronized with the log files on the disk:
flush = data |
Audit data should be synchronously written to disk to ensure log integrity. These parameters assure that all audit event data is fully synchronized with the log files on the disk. |
| IA-11 CM-6(a) |
Ensure Users Re-Authenticate for Privilege Escalation - sudo NOPASSWD | The sudo NOPASSWD tag, when specified, allows a user to execute commands using sudo without having to authenticate. This should be disabled by making sure that the NOPASSWD tag does not exist in /etc/sudoers configuration file or any sudo configuration snippets in /etc/sudoers.d/. |
Without re-authentication, users may access resources or perform tasks for which they
do not have authorization.
When operating systems provide the capability to escalate a functional capability, it is critical that the user re-authenticate. |
| AC-11(1) CM-6(a) AC-11(1).1 |
Implement Blank Screensaver |
To set the screensaver mode in the GNOME3 desktop to a blank screen,
add or set picture-uri to string '' in
/etc/dconf/db/local.d/00-security-settings. For example:
[org/gnome/desktop/screensaver] picture-uri=string ''Once the settings have been added, add a lock to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification. For example: /org/gnome/desktop/screensaver/picture-uriAfter the settings have been set, run dconf update. |
Setting the screensaver mode to blank-only conceals the contents of the display from passersby. |
| AU-12(c) | Ensure auditd Collects Information on the Use of Privileged Commands - reboot |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/sbin/reboot -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/sbin/reboot -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of the reboot command may cause availability issues for the system. |
| AC-12 SC-10 AC-2(5) CM-6(a) |
Set Interactive Session Timeout |
Setting the TMOUT option in /etc/profile ensures that
all user sessions will terminate based on inactivity.
The value of TMOUT should be exported and read only.
The TMOUT
setting in a file loaded by /etc/profile, e.g.
/etc/profile.d/tmout.sh should read as follows:
typeset -xr TMOUT=600or declare -xr TMOUT=600Using the typeset keyword is preferred for wider compatibility with ksh and other shells.
|
Terminating an idle session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended. |
| AU-12(c) | Ensure auditd Collects Information on the Use of Privileged Commands - shutdown |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/sbin/shutdown -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/sbin/shutdown -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of the shutdown command may cause availability issues for the system. |
| AU-12(b) | Verify Permissions on /etc/audit/rules.d/*.rules |
To properly set the permissions of /etc/audit/rules.d/*.rules, run the command:
$ sudo chmod 0640 /etc/audit/rules.d/*.rules |
Without the capability to restrict the roles and individuals that can select which events are audited, unauthorized personnel may be able to prevent the auditing of critical events. Misconfigured audits may degrade the system's performance by overwhelming the audit log. Misconfigured audits may also make it more difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. |
| AU-12(c) AU-12.1(iv) |
Record Attempts to Alter Process and Session Initiation Information btmp |
The audit system already collects process information for all
users and root. If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following lines to a file with suffix .rules in the
directory /etc/audit/rules.d in order to watch for attempted manual
edits of files involved in storing such process information:
-w /var/log/btmp -p wa -k sessionIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file in order to watch for attempted manual edits of files involved in storing such process information: -w /var/log/btmp -p wa -k session |
Manual editing of these files may indicate nefarious activity, such as an attacker attempting to remove evidence of an intrusion. |
| AU-12(a) CM-6(a) |
Install the psacct package |
The process accounting service, psacct, works with programs
including acct and ac to allow system administrators to view
user activity, such as commands issued by users of the system.
The psacct package can be installed with the following command:
$ sudo yum install psacct |
The psacct service can provide administrators a convenient view into some user activities. However, it should be noted that the auditing system and its audit records provide more authoritative and comprehensive records. |
| AU-12(c) | Ensure auditd Collects Information on the Use of Privileged Commands - init |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/sbin/init -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/sbin/init -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of the init command may cause availability issues for the system. |
| AU-12(c) AU-12.1(iv) AU-3 AU-3.1 AU-12(a) AU-12.1(ii) MA-4(1)(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - insmod |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-w /sbin/insmod -p x -k modules |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AU-12(c) | Ensure auditd Collects Information on the Use of Privileged Commands - poweroff |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-a always,exit -F path=/usr/sbin/poweroff -F auid>=1000 -F auid!=unset -F key=privilegedIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -a always,exit -F path=/usr/sbin/poweroff -F auid>=1000 -F auid!=unset -F key=privileged |
Misuse of the poweroff command may cause availability issues for the system. |
| AU-12(a) AU-12(c) CM-6(a) |
Configure Logging |
Ensure that the following line exists in
/etc/rsyslog.conf:
daemon.* /var/log/daemon.logConfigure logwatch or other log monitoring tools to summarize error conditions reported by the dhcpd process. |
By default, dhcpd logs notices to the daemon facility. Sending all daemon messages to a dedicated log file is part of the syslog configuration outlined in the Logging and Auditing section |
| AU-12(c) AU-12.1(iv) |
Record Attempts to Alter Process and Session Initiation Information wtmp |
The audit system already collects process information for all
users and root. If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following lines to a file with suffix .rules in the
directory /etc/audit/rules.d in order to watch for attempted manual
edits of files involved in storing such process information:
-w /var/log/wtmp -p wa -k sessionIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file in order to watch for attempted manual edits of files involved in storing such process information: -w /var/log/wtmp -p wa -k session |
Manual editing of these files may indicate nefarious activity, such as an attacker attempting to remove evidence of an intrusion. |
| AU-12(a) AU-12.1(ii) AU-3 AU-3.1 AU-12(c) AU-12.1(iv) MA-4(1)(a) |
Ensure auditd Collects Information on the Use of Privileged Commands - modprobe |
At a minimum, the audit system should collect the execution of
privileged commands for all users and root. If the auditd daemon is
configured to use the augenrules program to read audit rules during
daemon startup (the default), add a line of the following form to a file with
suffix .rules in the directory /etc/audit/rules.d:
-w /sbin/modprobe -p x -k modulesIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add a line of the following form to /etc/audit/audit.rules: -w /sbin/modprobe -p x -k modules |
Misuse of privileged functions, either intentionally or unintentionally by
authorized users, or by unauthorized external entities that have compromised system accounts,
is a serious and ongoing concern and can have significant adverse impacts on organizations.
Auditing the use of privileged functions is one way to detect such misuse and identify
the risk from insider and advanced persistent threats.
Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity. |
| AU-12(a) CM-6(a) |
Enable Process Accounting (psacct) |
The process accounting service, psacct, works with programs
including acct and ac to allow system administrators to view
user activity, such as commands issued by users of the system.
The psacct service can be enabled with the following command:
$ sudo systemctl enable psacct.service |
The psacct service can provide administrators a convenient view into some user activities. However, it should be noted that the auditing system and its audit records provide more authoritative and comprehensive records. |
| AU-12(c) AU-12.1(iv) |
Record Attempts to Alter Process and Session Initiation Information utmp |
The audit system already collects process information for all
users and root. If the auditd daemon is configured to use the
augenrules program to read audit rules during daemon startup (the
default), add the following lines to a file with suffix .rules in the
directory /etc/audit/rules.d in order to watch for attempted manual
edits of files involved in storing such process information:
-w /run/utmp -p wa -k sessionIf the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file in order to watch for attempted manual edits of files involved in storing such process information: -w /run/utmp -p wa -k session |
Manual editing of these files may indicate nefarious activity, such as an attacker attempting to remove evidence of an intrusion. |
| AU-12(b) | Verify Permissions on /etc/audit/auditd.conf |
To properly set the permissions of /etc/audit/auditd.conf, run the command:
$ sudo chmod 0640 /etc/audit/auditd.conf |
Without the capability to restrict the roles and individuals that can select which events are audited, unauthorized personnel may be able to prevent the auditing of critical events. Misconfigured audits may degrade the system's performance by overwhelming the audit log. Misconfigured audits may also make it more difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. |
| SC-12(2) SC-12(3) IA-7 SC-13 CM-6(a) SC-12 |
Ensure '/etc/system-fips' exists |
On a system where FIPS mode is enabled, /etc/system-fips must exist.
To enable FIPS mode, run the following command:
fips-mode-setup --enable |
Use of weak or untested encryption algorithms undermines the purposes of utilizing encryption to protect data. The operating system must implement cryptographic modules adhering to the higher standards approved by the federal government since this provides assurance they have been tested and validated. |
| SC-12(2) SC-12(3) IA-7 SC-13 CM-6(a) SC-12 |
Install the dracut-fips Package |
To enable FIPS, the system requires that the dracut-fips
package be installed.
The dracut-fips package can be installed with the following command:
$ sudo yum install dracut-fips |
Use of weak or untested encryption algorithms undermines the purposes of utilizing encryption to protect data. The operating system must implement cryptographic modules adhering to the higher standards approved by the federal government since this provides assurance they have been tested and validated. |
| SC-12(2) SC-12(3) IA-7 SC-13 CM-6(a) SC-12 |
Enable Dracut FIPS Module |
To enable FIPS mode, run the following command:
fips-mode-setup --enableTo enable FIPS, the system requires that the fips module is added in dracut configuration. Check if /etc/dracut.conf.d/40-fips.conf contain add_dracutmodules+=" fips " |
Use of weak or untested encryption algorithms undermines the purposes of utilizing encryption to protect data. The operating system must implement cryptographic modules adhering to the higher standards approved by the federal government since this provides assurance they have been tested and validated. |
| SC-12(2) SC-12(3) SC-13 |
Verify '/proc/sys/crypto/fips_enabled' exists |
On a system where FIPS 140-2 mode is enabled, /proc/sys/crypto/fips_enabled must exist.
To verify FIPS mode, run the following command:
cat /proc/sys/crypto/fips_enabled |
Use of weak or untested encryption algorithms undermines the purposes of utilizing encryption to protect data. The operating system must implement cryptographic modules adhering to the higher standards approved by the federal government since this provides assurance they have been tested and validated. |
| SC-12(2) SC-12(3) IA-7 SC-13 CM-6(a) SC-12 |
Enable the fips_mode SELinux Boolean |
By default, the SELinux boolean fips_mode is enabled.
This allows all SELinux domains to execute in fips_mode.
If this setting is disabled, it should be enabled.
To enable the fips_mode SELinux boolean, run the following command:
$ sudo setsebool -P fips_mode on |
|
| SC-12(2) SC-12(3) IA-7 SC-13 CM-6(a) SC-12 |
Install the dracut-fips-aesni Package |
To enable FIPS on system that support the Advanced Encryption Standard (AES) or New
Instructions (AES-NI) engine, the system requires that the dracut-fips-aesni
package be installed.
The dracut-fips-aesni package can be installed with the following command:
$ sudo yum install dracut-fips-aesni |
Use of weak or untested encryption algorithms undermines the purposes of utilizing encryption to protect data. The operating system must implement cryptographic modules adhering to the higher standards approved by the federal government since this provides assurance they have been tested and validated. |
| SC-12(2) SC-12(3) IA-7 SC-13 CM-6(a) SC-12 |
Set kernel parameter 'crypto.fips_enabled' to 1 |
System running in FIPS mode is indicated by kernel parameter
'crypto.fips_enabled'. This parameter should be set to 1 in FIPS mode.
To enable FIPS mode, run the following command:
fips-mode-setup --enableTo enable strict FIPS compliance, the fips=1 kernel option needs to be added to the kernel boot parameters during system installation so key generation is done with FIPS-approved algorithms and continuous monitoring tests in place. |
Use of weak or untested encryption algorithms undermines the purposes of utilizing encryption to protect data. The operating system must implement cryptographic modules adhering to the higher standards approved by the federal government since this provides assurance they have been tested and validated. |
| SC-12(2) SC-12(3) IA-7 SC-13 CM-6(a) SC-12 |
Enable FIPS Mode in GRUB2 |
To ensure FIPS mode is enabled, install package dracut-fips, and rebuild initramfs by running the following commands:
$ sudo yum install dracut-fips dracut -fAfter the dracut command has been run, add the argument fips=1 to the default GRUB 2 command line for the Linux operating system in /etc/default/grub, in the manner below: GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=VolGroup/LogVol06 rd.lvm.lv=VolGroup/lv_swap rhgb quiet rd.shell=0 fips=1"Finally, rebuild the grub.cfg file by using the grub2-mkconfig -ocommand as follows:
|
Use of weak or untested encryption algorithms undermines the purposes of utilizing encryption to protect data. The operating system must implement cryptographic modules adhering to the higher standards approved by the federal government since this provides assurance they have been tested and validated. |
| SC-12(2) SC-12(3) IA-7 SC-13 CM-6(a) SC-12 |
The Installed Operating System Is FIPS 140-2 Certified | To enable processing of sensitive information the operating system must provide certified cryptographic modules compliant with FIPS 140-2 standard. | The Federal Information Processing Standard (FIPS) Publication 140-2, (FIPS PUB 140-2) is a computer security standard. The standard specifies security requirements for cryptographic modules used to protect sensitive unclassified information. Refer to the full FIPS 140-2 standard at http://csrc.nist.gov/publications/fips/fips140-2/fips1402.pdf for further details on the requirements. FIPS 140-2 validation is required by U.S. law when information systems use cryptography to protect sensitive government information. In order to achieve FIPS 140-2 certification, cryptographic modules are subject to extensive testing by independent laboratories, accredited by National Institute of Standards and Technology (NIST). |
| SC-12(3) CM-6(a) |
Configure SSSD LDAP Backend Client to Demand a Valid Certificate from the Server |
Configure SSSD to demand a valid certificate from the server to
protect the integrity of LDAP remote access sessions by setting
the ldap_tls_reqcertoption in /etc/sssd/sssd.confto demand. |
Without a valid certificate presented to the LDAP client backend, the identity of a server can be forged compromising LDAP remote access sessions. |
| SC-12(3) CM-6(a) |
Configure SSSD LDAP Backend Client CA Certificate |
Configure SSSD to implement cryptography to protect the
integrity of LDAP remote access sessions. By setting
the ldap_tls_cacertoption in /etc/sssd/sssd.confto point to the path for the X.509 certificates used for peer authentication. ldap_tls_cacert /path/to/tls/ca.cert |
Without cryptographic integrity protections, information can be altered by
unauthorized users without detection.
Cryptographic mechanisms used for protecting the integrity of information include, for example, signed hash functions using asymmetric cryptography enabling distribution of the public key to verify the hash information while maintaining the confidentiality of the key used to generate the hash. |
| SC-12(3) CM-6(a) |
Configure SSSD LDAP Backend Client CA Certificate Location |
Configure SSSD to implement cryptography to protect the
integrity of LDAP remote access sessions. By setting
the ldap_tls_cacertdiroption in /etc/sssd/sssd.confto point to the path for the X.509 certificates used for peer authentication. ldap_tls_cacertdir /path/to/tls/cacert |
Without cryptographic integrity protections, information can be altered by
unauthorized users without detection.
Cryptographic mechanisms used for protecting the integrity of information include, for example, signed hash functions using asymmetric cryptography enabling distribution of the public key to verify the hash information while maintaining the confidentiality of the key used to generate the hash. |
| SC-13 CM-6(a) |
Disable Prelinking |
The prelinking feature changes binaries in an attempt to decrease their startup
time. In order to disable it, change or add the following line inside the file
/etc/sysconfig/prelink:
PRELINKING=noNext, run the following command to return binaries to a normal, non-prelinked state: $ sudo /usr/sbin/prelink -ua |
Because the prelinking feature changes binaries, it can interfere with the operation of certain software and/or modes such as AIDE, FIPS, etc. |
| SC-13 SC-12(2) SC-12(3) |
Configure BIND to use System Crypto Policy | Crypto Policies provide a centralized control over crypto algorithms usage of many packages. BIND is supported by crypto policy, but the BIND configuration may be set up to ignore it. To check that Crypto Policies settings are configured correctly, ensure that the /etc/named.conf includes the appropriate configuration: In the options section of /etc/named.conf, make sure that the following line is not commented out or superseded by later includes: include "/etc/crypto-policies/back-ends/bind.config"; | Overriding the system crypto policy makes the behavior of the BIND service violate expectations, and makes system configuration more fragmented. |
| SC-13 SC-12(2) SC-12(3) |
Configure Kerberos to use System Crypto Policy | Crypto Policies provide a centralized control over crypto algorithms usage of many packages. Kerberos is supported by crypto policy, but it's configuration may be set up to ignore it. To check that Crypto Policies settings for Kerberos are configured correctly, examine that there is a symlink at /etc/krb5.conf.d/crypto-policies targeting /etc/cypto-policies/back-ends/krb5.config. If the symlink exists, Kerberos is configured to use the system-wide crypto policy settings. | Overriding the system crypto policy makes the behavior of Kerberos violate expectations, and makes system configuration more fragmented. |
| SI-16 | Enable Kernel Page-Table Isolation (KPTI) | To enable Kernel page-table isolation, add the argument pti=on to all BLS (Boot Loader Specification) entries ('options' line) for the Linux operating system in /boot/loader/entries/*.conf. | Kernel page-table isolation is a kernel feature that mitigates the Meltdown security vulnerability and hardens the kernel against attempts to bypass kernel address space layout randomization (KASLR). |
| SI-16 | Enable Kernel Page-Table Isolation (KPTI) |
To enable Kernel page-table isolation,
add the argument pti=on to the default
GRUB 2 command line for the Linux operating system.
To ensure that pti=on is added as a kernel command line
argument to newly installed kernels, add pti=on to the
default Grub2 command line for Linux operating systems. Modify the line within
/etc/default/grub as shown below:
GRUB_CMDLINE_LINUX="... pti=on ..."Run the following command to update command line for already installed kernels: # grubby --update-kernel=ALL --args="pti=on" |
Kernel page-table isolation is a kernel feature that mitigates the Meltdown security vulnerability and hardens the kernel against attempts to bypass kernel address space layout randomization (KASLR). |
| AC-17(a) AC-17(2) CM-6(a) MA-4(6) SC-13 SC-12(2) SC-12(3) |
Configure OpenSSL library to use System Crypto Policy | Crypto Policies provide a centralized control over crypto algorithms usage of many packages. OpenSSL is supported by crypto policy, but the OpenSSL configuration may be set up to ignore it. To check that Crypto Policies settings are configured correctly, you have to examine the OpenSSL config file available under /etc/pki/tls/openssl.cnf. This file has the ini format, and it enables crypto policy support if there is a [ crypto_policy ] section that contains the .include /etc/crypto-policies/back-ends/opensslcnf.config directive. | Overriding the system crypto policy makes the behavior of the Java runtime violates expectations, and makes system configuration more fragmented. |
| AC-17(a) CM-7(a) CM-7(b) CM-6(a) |
Do Not Allow SSH Environment Options |
Ensure that users are not able to override environment variables of the SSH daemon.
The default SSH configuration disables environment processing. The appropriate configuration is used if no value is set for PermitUserEnvironment. To explicitly disable Environment options, add or correct the following /etc/ssh/sshd_config: PermitUserEnvironment no |
SSH environment options potentially allow users to bypass access restriction in some configurations. |
| AC-17(a) AC-17(1) CM-6(a) |
Set SSH Daemon LogLevel to VERBOSE |
The VERBOSE parameter configures the SSH daemon to record login and logout activity.
To specify the log level in
SSH, add or correct the following line in
/etc/ssh/sshd_config:
LogLevel VERBOSE |
SSH provides several logging levels with varying amounts of verbosity. DEBUG is specifically not recommended other than strictly for debugging SSH communications since it provides so much data that it is difficult to identify important security information. INFO or VERBOSE level is the basic level that only records login activity of SSH users. In many situations, such as Incident Response, it is important to determine when a particular user was active on a system. The logout record can eliminate those users who disconnected, which helps narrow the field. |
| AC-17 (2) | The File /etc/ssh/sshd_config.d/50-redhat.conf Must Exist | The /etc/ssh/sshd_config.d/50-redhat.conf file must exist as it contains important settings to secure SSH. | The file must exist to configure SSH correctly. |
| AC-17(a) MA-4(6) CM-6(a) AC-4 SC-8 |
Verify Any Configured IPSec Tunnel Connections | Libreswan provides an implementation of IPsec and IKE, which permits the creation of secure tunnels over untrusted networks. As such, IPsec can be used to circumvent certain network requirements such as filtering. Verify that if any IPsec connection (conn) configured in /etc/ipsec.conf and /etc/ipsec.d exists is an approved organizational connection. | IP tunneling mechanisms can be used to bypass network filtering. |
| AC-17(a) CM-7(a) CM-7(b) CM-6(a) |
Disable Kerberos Authentication |
Unless needed, SSH should not permit extraneous or unnecessary
authentication mechanisms like Kerberos.
The default SSH configuration disallows authentication validation through Kerberos. The appropriate configuration is used if no value is set for KerberosAuthentication. To explicitly disable Kerberos authentication, add or correct the following line in /etc/ssh/sshd_config: KerberosAuthentication no |
Kerberos authentication for SSH is often implemented using GSSAPI. If Kerberos is enabled through SSH, the SSH daemon provides a means of access to the system's Kerberos implementation. Configuring these settings for the SSH daemon provides additional assurance that remote logon via SSH will not use unused methods of authentication, even in the event of misconfiguration elsewhere. |
| AC-17 (2) | SSHD Must Include System Crypto Policy Config File | SSHD should follow the system cryptographic policy. In order to accomplish this the SSHD configuration should include the system | Without cryptographic integrity protections, information can be altered by unauthorized users without detection. |
| AC-17(a) AC-17(2) CM-6(a) MA-4(6) SC-13 SC-12(2) SC-12(3) |
Configure System Cryptography Policy |
To configure the system cryptography policy to use ciphers only from the DEFAULT
policy, run the following command:
$ sudo update-crypto-policies --set DEFAULTThe rule checks if settings for selected crypto policy are configured as expected. Configuration files in the /etc/crypto-policies/back-ends are either symlinks to correct files provided by Crypto-policies package or they are regular files in case crypto policy customizations are applied. Crypto policies may be customized by crypto policy modules, in which case it is delimited from the base policy using a colon. |
Centralized cryptographic policies simplify applying secure ciphers across an operating system and the applications that run on that operating system. Use of weak or untested encryption algorithms undermines the purposes of utilizing encryption to protect data. |
| AC-17 (1) | Firewalld Must Employ a Deny-all, Allow-by-exception Policy for Allowing Connections to Other Systems | Red Hat Enterprise Linux 8 incorporates the "firewalld" daemon, which allows for many different configurations. One of these configurations is zones. Zones can be utilized to a deny-all, allow-by-exception approach. The default "drop" zone will drop all incoming network packets unless it is explicitly allowed by the configuration file or is related to an outgoing network connection. | Failure to restrict network connectivity only to authorized systems permits inbound connections from malicious systems. It also permits outbound connections that may facilitate exfiltration of data. |
| AC-17(a) CM-6(a) AC-6(1) |
Verify Group Who Owns SSH Server config file |
To properly set the group owner of /etc/ssh/sshd_config, run the command:
$ sudo chgrp root /etc/ssh/sshd_config |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct group to prevent unauthorized changes. |
| AC-17(a) CM-7(a) CM-7(b) CM-6(a) |
Disable Compression Or Set Compression to delayed |
Compression is useful for slow network connections over long
distances but can cause performance issues on local LANs. If use of compression
is required, it should be enabled only after a user has authenticated; otherwise,
it should be disabled. To disable compression or delay compression until after
a user has successfully authenticated, add or correct the following line in the
/etc/ssh/sshd_config file:
Compression no |
If compression is allowed in an SSH connection prior to authentication, vulnerabilities in the compression software could result in compromise of the system from an unauthenticated connection, potentially with root privileges. |
| AC-17(a) CM-6(a) AC-6(1) |
Verify Permissions on SSH Server config file |
To properly set the permissions of /etc/ssh/sshd_config, run the command:
$ sudo chmod 0600 /etc/ssh/sshd_config |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct group to prevent unauthorized changes. |
| AC-17(a) CM-7(a) CM-7(b) CM-6(a) |
Disable SSH Support for Rhosts RSA Authentication |
SSH can allow authentication through the obsolete rsh
command through the use of the authenticating user's SSH keys. This should be disabled.
To ensure this behavior is disabled, add or correct the following line in /etc/ssh/sshd_config: RhostsRSAAuthentication no |
Configuring this setting for the SSH daemon provides additional assurance that remote login via SSH will require a password, even in the event of misconfiguration elsewhere. |
| AC-17(a) CM-6(a) AC-6(1) |
Verify Permissions on SSH Server Public *.pub Key Files |
To properly set the permissions of /etc/ssh/*.pub, run the command: $ sudo chmod 0644 /etc/ssh/*.pub |
If a public host key file is modified by an unauthorized user, the SSH service may be compromised. |
| AC-17(a) AC-17(2) CM-6(a) MA-4(6) SC-13 |
Configure SSH to use System Crypto Policy | Crypto Policies provide a centralized control over crypto algorithms usage of many packages. SSH is supported by crypto policy, but the SSH configuration may be set up to ignore it. To check that Crypto Policies settings are configured correctly, ensure that the CRYPTO_POLICY variable is either commented or not set at all in the /etc/sysconfig/sshd. | Overriding the system crypto policy makes the behavior of the SSH service violate expectations, and makes system configuration more fragmented. |
| AC-17(a) CM-6(a) AC-6(1) |
Verify Owner on SSH Server config file |
To properly set the owner of /etc/ssh/sshd_config, run the command:
$ sudo chown root /etc/ssh/sshd_config |
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct group to prevent unauthorized changes. |
| AC-17(a) AC-17(2) CM-6(a) MA-4(6) SC-13 SC-12(2) SC-12(3) |
Harden SSHD Crypto Policy | Crypto Policies are means of enforcing certain cryptographic settings for selected applications including OpenSSH server. The SSHD service is by default configured to modify its configuration based on currently configured Crypto-Policy. However, in certain cases it might be needed to override the Crypto Policy specific to OpenSSH Server and leave rest of the Crypto Policy intact. This can be done by dropping a file named opensshserver-xxx.config, replacing xxx with arbitrary identifier, into /etc/crypto-policies/local.d. This has to be followed by running update-crypto-policies so that changes are applied. Changes are propagated into /etc/crypto-policies/back-ends/opensshserver.config. This rule checks if this file contains predefined CRYPTO_POLICY environment variable configured with predefined value. | The Common Criteria requirements specify that certain parameters for OpenSSH Server are configured e.g. supported ciphers, accepted host key algorithms, public key types, key exchange algorithms, HMACs and GSSAPI key exchange is disabled. Currently particular requirements specified by CC are stricter compared to any existing Crypto Policy. |
| AC-17(a) CM-7(a) CM-7(b) CM-6(a) |
Disable SSH Support for User Known Hosts |
SSH can allow system users to connect to systems if a cache of the remote
systems public keys is available. This should be disabled.
To ensure this behavior is disabled, add or correct the following line in /etc/ssh/sshd_config: IgnoreUserKnownHosts yes |
Configuring this setting for the SSH daemon provides additional assurance that remote login via SSH will require a password, even in the event of misconfiguration elsewhere. |
| AC-17(a) CM-6(a) |
Set LogLevel to INFO |
The INFO parameter specifices that record login and logout activity will be logged.
The default SSH configuration sets the log level to INFO. The appropriate configuration is used if no value is set for LogLevel. To explicitly specify the log level in SSH, add or correct the following line in /etc/ssh/sshd_config: LogLevel INFO |
SSH provides several logging levels with varying amounts of verbosity. DEBUG is specifically not recommended other than strictly for debugging SSH communications since it provides so much data that it is difficult to identify important security information. INFO level is the basic level that only records login activity of SSH users. In many situations, such as Incident Response, it is important to determine when a particular user was active on a system. The logout record can eliminate those users who disconnected, which helps narrow the field. |
| AC-17(a) CM-7(a) CM-7(b) CM-6(a) |
Disable SSH Support for .rhosts Files |
SSH can emulate the behavior of the obsolete rsh
command in allowing users to enable insecure access to their
accounts via .rhosts files.
The default SSH configuration disables support for .rhosts. The appropriate configuration is used if no value is set for IgnoreRhosts. To explicitly disable support for .rhosts files, add or correct the following line in /etc/ssh/sshd_config: IgnoreRhosts yes |
SSH trust relationships mean a compromise on one host can allow an attacker to move trivially to other hosts. |
| AC-17(a) CM-6(a) |
Enable the LDAP Client For Use in Authconfig |
To determine if LDAP is being used for authentication, use the following
command:
$ sudo grep -i useldapauth /etc/sysconfig/authconfig If USELDAPAUTH=yes, then LDAP is being used. If not, set USELDAPAUTH to yes. |
Without cryptographic integrity protections, information can be altered by unauthorized users without detection. The ssl directive specifies whether to use TLS or not. If not specified it will default to no. It should be set to start_tls rather than doing LDAP over SSL. |
| AC-17(a) CM-6(a) AC-6(1) |
Verify Permissions on SSH Server Private *_key Key Files |
SSH server private keys - files that match the /etc/ssh/*_key glob, have to have restricted permissions.
If those files are owned by the root user and the root group, they have to have the 0600 permission or stricter.
If they are owned by the root user, but by a dedicated group ssh_keys, they can have the 0640 permission or stricter.
|
If an unauthorized user obtains the private SSH host key file, the host could be impersonated. |
| AC-17(a) CM-6(b) CM-7(a) CM-7(b) |
Enable SSH Server firewalld Firewall Exception |
If the SSH server is in use, inbound connections to SSH's port should be allowed to permit
remote access through SSH. In more restrictive firewalld settings, the SSH port should be
added to the proper firewalld zone in order to allow SSH remote access.
To configure firewalld to allow ssh access, run the following command(s):
firewall-cmd --permanent --add-service=sshThen run the following command to load the newly created rule(s): firewall-cmd --reload |
If inbound SSH connections are expected, adding the SSH port to the proper firewalld zone will allow remote access through the SSH port. |
| AC-17(a) AC-17(2) CM-6(a) MA-4(6) SC-13 |
Harden SSH client Crypto Policy | Crypto Policies are means of enforcing certain cryptographic settings for selected applications including OpenSSH client. To override the system wide crypto policy for Openssh client, place a file in the /etc/ssh/ssh_config.d/ so that it is loaded before the 05-redhat.conf. In this case it is file named 02-ospp.conf containing parameters which need to be changed with respect to the crypto policy. This rule checks if the file exists and if it contains required parameters and values which modify the Crypto Policy. During the parsing process, as soon as Openssh client parses some configuration option and its value, it remembers it and ignores any subsequent overrides. The customization mechanism provided by crypto policies appends eventual customizations at the end of the system wide crypto policy. Therefore, if the crypto policy customization overrides some parameter which is already configured in the system wide crypto policy, the SSH client will not honor that customized parameter. | The Common Criteria requirements specify how certain parameters for OpenSSH Client are configured. Particular parameters are RekeyLimit, GSSAPIAuthentication, Ciphers, PubkeyAcceptedKeyTypes, MACs and KexAlgorithms. Currently particular requirements specified by CC are stricter compared to any existing Crypto Policy. |
| AC-17(a) AC-17(2) CM-6(a) SC-12(a) SC-12(b) |
Configure LDAP Client to Use TLS For All Transactions |
This check verifies cryptography has been implemented
to protect the integrity of remote LDAP authentication sessions.
To determine if LDAP is being used for authentication, use the following command: $ sudo grep -i useldapauth /etc/sysconfig/authconfig If USELDAPAUTH=yes, then LDAP is being used. To check if LDAP is configured to use TLS, use the following command: $ sudo grep -i ssl /etc/pam_ldap.conf |
Without cryptographic integrity protections, information can be altered by unauthorized users without detection. The ssl directive specifies whether to use TLS or not. If not specified it will default to no. It should be set to start_tls rather than doing LDAP over SSL. |
| AC-17(a) CM-7(a) CM-7(b) CM-6(a) |
Disable SSH Access via Empty Passwords |
Disallow SSH login with empty passwords.
The default SSH configuration disables logins with empty passwords. The appropriate
configuration is used if no value is set for PermitEmptyPasswords.
To explicitly disallow SSH login from accounts with empty passwords, add or correct the following line in /etc/ssh/sshd_config: PermitEmptyPasswords noAny accounts with empty passwords should be disabled immediately, and PAM configuration should prevent users from being able to assign themselves empty passwords. |
Configuring this setting for the SSH daemon provides additional assurance that remote login via SSH will require a password, even in the event of misconfiguration elsewhere. |
| AC-17(1) AU-14(1) AU-10 CM-6(a) IR-5(1) |
Enable Auditing for Processes Which Start Prior to the Audit Daemon |
To ensure all processes can be audited, even those which start
prior to the audit daemon, add the argument audit=1 to the default
GRUB 2 command line for the Linux operating system.
To ensure that audit=1 is added as a kernel command line
argument to newly installed kernels, add audit=1 to the
default Grub2 command line for Linux operating systems. Modify the line within
/etc/default/grub as shown below:
GRUB_CMDLINE_LINUX="... audit=1 ..."Run the following command to update command line for already installed kernels: # grubby --update-kernel=ALL --args="audit=1" |
Each process on the system carries an "auditable" flag which indicates whether its activities can be audited. Although auditd takes care of enabling this for all processes which launch after it does, adding the kernel argument ensures it is set for every process during boot. |
| AC-17(1) AU-14(1) AU-10 CM-6(a) IR-5(1) |
Enable Auditing for Processes Which Start Prior to the Audit Daemon | To ensure all processes can be audited, even those which start prior to the audit daemon, add the argument audit=1 to all BLS (Boot Loader Specification) entries ('options' line) for the Linux operating system in /boot/loader/entries/*.conf. | Each process on the system carries an "auditable" flag which indicates whether its activities can be audited. Although auditd takes care of enabling this for all processes which launch after it does, adding the kernel argument ensures it is set for every process during boot. |
| AC-17(1) | Ensure remote access methods are monitored in Rsyslog |
Logging of remote access methods must be implemented to help identify cyber
attacks and ensure ongoing compliance with remote access policies are being
audited and upheld. An examples of a remote access method is the use of the
Remote Desktop Protocol (RDP) from an external, non-organization controlled
network. The /etc/rsyslog.conf or
/etc/rsyslog.d/*.conf file should contain a match for the following
selectors: auth.*, authpriv.*, and daemon.*. If
not, use the following as an example configuration:
auth.*;authpriv.* /var/log/secure
daemon.* /var/log/messages
|
Logging remote access methods can be used to trace the decrease the risks associated with remote user access management. It can also be used to spot cyber attacks and ensure ongoing compliance with organizational policies surrounding the use of remote access methods. |
| AC-17(2) | Configure OpenSSL library to use TLS Encryption |
Crypto Policies are means of enforcing certain cryptographic settings for
selected applications including OpenSSL. OpenSSL is by default configured to
modify its configuration based on currently configured Crypto Policy.
Editing the Crypto Policy back-end is not recommended.
Check the crypto-policies(7) man page and choose a policy that configures TLS
protocol to version 1.2 or higher, for example DEFAULT, FUTURE or FIPS policy.
Or create and apply a custom policy that restricts minimum TLS version to 1.2.
For example for versions prior to crypto-policies-20210617-1.gitc776d3e.el8.noarch
this is expected:
$ sudo grep -i MinProtocol /etc/crypto-policies/back-ends/opensslcnf.config MinProtocol = TLSv1.2Or for version crypto-policies-20210617-1.gitc776d3e.el8.noarch and newer this is expected: $ sudo grep -i MinProtocol /etc/crypto-policies/back-ends/opensslcnf.config TLS.MinProtocol = TLSv1.2 DTLS.MinProtocol = DTLSv1.2 |
Without cryptographic integrity protections, information can be altered by unauthorized users without detection. |
| AC-17(2) | Use Only FIPS 140-2 Validated Key Exchange Algorithms |
Limit the key exchange algorithms to those which are FIPS-approved.
Add or modify the following line in /etc/crypto-policies/back-ends/opensshserver.config
CRYPTO_POLICY='-oKexAlgorithms=ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512'This rule ensures that only the key exchange algorithms mentioned above (or their subset) are configured for use, keeping the given order of algorithms. |
DoD information systems are required to use FIPS-approved key exchange algorithms. The system will attempt to use the first algorithm presented by the client that matches the server list. Listing the values "strongest to weakest" is a method to ensure the use of the strongest algorithm available to secure the SSH connection. |
| AC-17(2) | Configure SSH Server to Use FIPS 140-2 Validated Ciphers: opensshserver.config |
Crypto Policies provide a centralized control over crypto algorithms usage of many packages.
OpenSSH is supported by system crypto policy, but the OpenSSH configuration may be
set up incorrectly.
To check that Crypto Policies settings for ciphers are configured correctly, ensure that
/etc/crypto-policies/back-ends/opensshserver.config contains the following
text and is not commented out:
-oCiphers=aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc,aes192-cbc,aes256-cbc,rijndael-cbc@lysator.liu.se |
Overriding the system crypto policy makes the behavior of the OpenSSH server violate expectations, and makes system configuration more fragmented. By specifying a cipher list with the order of ciphers being in a “strongest to weakest” orientation, the system will automatically attempt to use the strongest cipher for securing SSH connections. |
| AC-17(2) | Configure SSH Server to Use FIPS 140-2 Validated MACs: opensshserver.config | Crypto Policies provide a centralized control over crypto algorithms usage of many packages. OpenSSH is supported by system crypto policy, but the OpenSSH configuration may be set up incorrectly. To check that Crypto Policies settings are configured correctly, ensure that /etc/crypto-policies/back-ends/opensshserver.config contains the following text and is not commented out: -oMACS=hmac-sha2-512,hmac-sha2-256,hmac-sha1,hmac-sha1-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com | Overriding the system crypto policy makes the behavior of the OpenSSH server violate expectations, and makes system configuration more fragmented. |
| AC-17(2) | Configure SSH Client to Use FIPS 140-2 Validated MACs: openssh.config | Crypto Policies provide a centralized control over crypto algorithms usage of many packages. OpenSSH is supported by system crypto policy, but the OpenSSH configuration may be set up incorrectly. To check that Crypto Policies settings are configured correctly, ensure that /etc/crypto-policies/back-ends/openssh.config contains the following line and is not commented out: MACs hmac-sha2-512,hmac-sha2-256,hmac-sha1,hmac-sha1-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com | Overriding the system crypto policy makes the behavior of the OpenSSH client violate expectations, and makes system configuration more fragmented. |
| AC-17(2) | Configure GnuTLS library to use DoD-approved TLS Encryption | Crypto Policies provide a centralized control over crypto algorithms usage of many packages. GnuTLS is supported by system crypto policy, but the GnuTLS configuration may be set up to ignore it. To check that Crypto Policies settings are configured correctly, ensure that /etc/crypto-policies/back-ends/gnutls.config contains the following line and is not commented out: +VERS-ALL:-VERS-DTLS0.9:-VERS-SSL3.0:-VERS-TLS1.0:-VERS-TLS1.1:-VERS-DTLS1.0 | Overriding the system crypto policy makes the behavior of the GnuTLS library violate expectations, and makes system configuration more fragmented. |
| AC-17(2) | Configure SSH Client to Use FIPS 140-2 Validated Ciphers: openssh.config |
Crypto Policies provide a centralized control over crypto algorithms usage of many packages.
OpenSSH is supported by system crypto policy, but the OpenSSH configuration may be
set up incorrectly.
To check that Crypto Policies settings for ciphers are configured correctly, ensure that
/etc/crypto-policies/back-ends/openssh.config contains the following
line and is not commented out:
Ciphers aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc,aes192-cbc,aes256-cbc,rijndael-cbc@lysator.liu.se |
Overriding the system crypto policy makes the behavior of the OpenSSH client violate expectations, and makes system configuration more fragmented. By specifying a cipher list with the order of ciphers being in a “strongest to weakest” orientation, the system will automatically attempt to use the strongest cipher for securing SSH connections. |
| AC-18(a) AC-18(3) CM-7(a) CM-7(b) CM-6(a) MP-7 AC-18(4) |
Disable Kernel iwlwifi Module |
To configure the system to prevent the iwlwifi
kernel module from being loaded, add the following line to the file /etc/modprobe.d/iwlwifi.conf:
install iwlwifi /bin/falseTo configure the system to prevent the iwlwifi from being used,
add the following line to file /etc/modprobe.d/iwlwifi.conf:
blacklist iwlwifi |
If Wireless functionality must be disabled, preventing the kernel from loading the kernel module provides an additional safeguard against its activation. |
| AC-18 | Disable IEEE 1394 (FireWire) Support |
The IEEE 1394 (FireWire) is a serial bus standard for
high-speed real-time communication.
To configure the system to prevent the firewire-core
kernel module from being loaded, add the following line to the file /etc/modprobe.d/firewire-core.conf:
install firewire-core /bin/falseTo configure the system to prevent the firewire-core from being used,
add the following line to file /etc/modprobe.d/firewire-core.conf:
blacklist firewire-core |
Disabling FireWire protects the system against exploitation of any flaws in its implementation. |
| AC-18 | Disable CAN Support |
The Controller Area Network (CAN) is a serial communications
protocol which was initially developed for automotive and
is now also used in marine, industrial, and medical applications.
To configure the system to prevent the can
kernel module from being loaded, add the following line to the file /etc/modprobe.d/can.conf:
install can /bin/falseTo configure the system to prevent the can from being used,
add the following line to file /etc/modprobe.d/can.conf:
blacklist can |
Disabling CAN protects the system against exploitation of any flaws in its implementation. |
| AC-18(a) AC-18(3) CM-7(a) CM-7(b) CM-6(a) MP-7 |
Disable WiFi or Bluetooth in BIOS | Some machines that include built-in wireless support offer the ability to disable the device through the BIOS. This is hardware-specific; consult your hardware manual or explore the BIOS setup during boot. | Disabling wireless support in the BIOS prevents easy activation of the wireless interface, generally requiring administrators to reboot the system first. |
| AC-18(a) AC-18(3) CM-7(a) CM-7(b) CM-6(a) MP-7 |
Disable Bluetooth Kernel Module |
The kernel's module loading system can be configured to prevent
loading of the Bluetooth module. Add the following to
the appropriate /etc/modprobe.d configuration file
to prevent the loading of the Bluetooth module:
install bluetooth /bin/true |
If Bluetooth functionality must be disabled, preventing the kernel from loading the kernel module provides an additional safeguard against its activation. |
| AC-18(a) AC-18(3) CM-7(a) CM-7(b) CM-6(a) MP-7 AC-18(4) |
Disable Kernel mac80211 Module |
To configure the system to prevent the mac80211
kernel module from being loaded, add the following line to the file /etc/modprobe.d/mac80211.conf:
install mac80211 /bin/falseTo configure the system to prevent the mac80211 from being used,
add the following line to file /etc/modprobe.d/mac80211.conf:
blacklist mac80211 |
If Wireless functionality must be disabled, preventing the kernel from loading the kernel module provides an additional safeguard against its activation. |
| AC-18(a) AC-18(3) CM-7(a) CM-7(b) CM-6(a) MP-7 AC-18(4) |
Disable Kernel cfg80211 Module |
To configure the system to prevent the cfg80211
kernel module from being loaded, add the following line to the file /etc/modprobe.d/cfg80211.conf:
install cfg80211 /bin/falseTo configure the system to prevent the cfg80211 from being used,
add the following line to file /etc/modprobe.d/cfg80211.conf:
blacklist cfg80211 |
If Wireless functionality must be disabled, preventing the kernel from loading the kernel module provides an additional safeguard against its activation. |
| AC-18(a) AC-18(3) CM-7(a) CM-7(b) CM-6(a) MP-7 AC-18(4) |
Disable Kernel iwlmvm Module |
To configure the system to prevent the iwlmvm
kernel module from being loaded, add the following line to the file /etc/modprobe.d/iwlmvm.conf:
install iwlmvm /bin/falseTo configure the system to prevent the iwlmvm from being used,
add the following line to file /etc/modprobe.d/iwlmvm.conf:
blacklist iwlmvm |
If Wireless functionality must be disabled, preventing the kernel from loading the kernel module provides an additional safeguard against its activation. |
| AC-18(a) AC-18(3) CM-7(a) CM-7(b) CM-6(a) MP-7 |
Deactivate Wireless Network Interfaces |
Deactivating wireless network interfaces should prevent normal usage of the wireless
capability.
Configure the system to disable all wireless network interfaces with the following command: $ sudo nmcli radio all off |
The use of wireless networking can introduce many different attack vectors into the organization's network. Common attack vectors such as malicious association and ad hoc networks will allow an attacker to spoof a wireless access point (AP), allowing validated systems to connect to the malicious AP and enabling the attacker to monitor and record network traffic. These malicious APs can also serve to create a man-in-the-middle attack or be used to create a denial of service to valid network resources. |
| AC-18 | Disable ATM Support |
The Asynchronous Transfer Mode (ATM) is a protocol operating on
network, data link, and physical layers, based on virtual circuits
and virtual paths.
To configure the system to prevent the atm
kernel module from being loaded, add the following line to the file /etc/modprobe.d/atm.conf:
install atm /bin/falseTo configure the system to prevent the atm from being used,
add the following line to file /etc/modprobe.d/atm.conf:
blacklist atm |
Disabling ATM protects the system against exploitation of any flaws in its implementation. |
| AC-18(a) AC-18(3) CM-7(a) CM-7(b) CM-6(a) MP-7 |
Disable Bluetooth Service |
The bluetooth service can be disabled with the following command:
$ sudo systemctl mask --now bluetooth.service $ sudo service bluetooth stop |
Disabling the bluetooth service prevents the system from attempting connections to Bluetooth devices, which entails some security risk. Nevertheless, variation in this risk decision may be expected due to the utility of Bluetooth connectivity and its limited range. |
| AC-18(4) CM-6(a) |
Prevent non-Privileged Users from Modifying Network Interfaces using nmcli |
By default, non-privileged users are given permissions to modify networking
interfaces and configurations using the nmcli command. Non-privileged
users should not be making configuration changes to network configurations. To
ensure that non-privileged users do not have permissions to make changes to the
network configuration using nmcli, create the following configuration in
/etc/polkit-1/localauthority/20-org.d/10-nm-harden-access.pkla:
[Disable General User Access to NetworkManager] Identity=default Action=org.freedesktop.NetworkManager.* ResultAny=no ResultInactive=no ResultActive=auth_admin |
Allowing non-privileged users to make changes to network settings can allow untrusted access, prevent system availability, and/or can lead to a compromise or attack. |
| SC-20(a) CM-6(a) |
Configure Multiple DNS Servers in /etc/resolv.conf |
Determine whether the system is using local or DNS name resolution with the
following command:
$ sudo grep hosts /etc/nsswitch.conf hosts: files dnsIf the DNS entry is missing from the host's line in the "/etc/nsswitch.conf" file, the "/etc/resolv.conf" file must be empty. Verify the "/etc/resolv.conf" file is empty with the following command: $ sudo ls -al /etc/resolv.conf -rw-r--r-- 1 root root 0 Aug 19 08:31 resolv.confIf the DNS entry is found on the host's line of the "/etc/nsswitch.conf" file, then verify the following: Multiple Domain Name System (DNS) Servers should be configured in /etc/resolv.conf. This provides redundant name resolution services in the event that a domain server crashes. To configure the system to contain as least 2 DNS servers, add a corresponding nameserver ip_address entry in /etc/resolv.conf for each DNS server where ip_address is the IP address of a valid DNS server. For example: search example.com nameserver 192.168.0.1 nameserver 192.168.0.2 |
To provide availability for name resolution services, multiple redundant name servers are mandated. A failure in name resolution could lead to the failure of security functions requiring name resolution, which may include time synchronization, centralized authentication, and remote system logging. |
| SC-24 | Enable systemd-journald Service |
The systemd-journald service is an essential component of
systemd.
The systemd-journald service can be enabled with the following command:
$ sudo systemctl enable systemd-journald.service |
In the event of a system failure, Red Hat Enterprise Linux 8 must preserve any information necessary to determine cause of failure and any information necessary to return to operations with least disruption to system processes. |
| SC-30 SC-30(2) CM-6(a) |
Enable Randomized Layout of Virtual Address Space |
To set the runtime status of the kernel.randomize_va_space kernel parameter, run the following command: $ sudo sysctl -w kernel.randomize_va_space=2To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: kernel.randomize_va_space = 2 |
Address space layout randomization (ASLR) makes it more difficult for an attacker to predict the location of attack code they have introduced into a process's address space during an attempt at exploitation. Additionally, ASLR makes it more difficult for an attacker to know the location of existing code in order to re-purpose it using return oriented programming (ROP) techniques. |
| SC-30 SC-30(2) SC-30(5) CM-6(a) |
Restrict Exposed Kernel Pointer Addresses Access |
To set the runtime status of the kernel.kptr_restrict kernel parameter, run the following command: $ sudo sysctl -w kernel.kptr_restrict=1To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: kernel.kptr_restrict = 1 |
Exposing kernel pointers (through procfs or seq_printf()) exposes kernel writeable structures which may contain functions pointers. If a write vulnerability occurs in the kernel, allowing write access to any of this structure, the kernel can be compromised. This option disallow any program without the CAP_SYSLOG capability to get the addresses of kernel pointers by replacing them with 0. |
| SC-39 CM-6(a) |
Enable NX or XD Support in the BIOS | Reboot the system and enter the BIOS or Setup configuration menu. Navigate the BIOS configuration menu and make sure that the option is enabled. The setting may be located under a Security section. Look for Execute Disable (XD) on Intel-based systems and No Execute (NX) on AMD-based systems. | Computers with the ability to prevent this type of code execution frequently put an option in the BIOS that will allow users to turn the feature on or off at will. |
| SC-39 CM-6(a) |
Enable ExecShield via sysctl | By default on Red Hat Enterprise Linux 8 64-bit systems, ExecShield is enabled and can only be disabled if the hardware does not support ExecShield or is disabled in /etc/default/grub. | ExecShield uses the segmentation feature on all x86 systems to prevent execution in memory higher than a certain address. It writes an address as a limit in the code segment descriptor, to control where code can be executed, on a per-process basis. When the kernel places a process's memory regions such as the stack and heap higher than this address, the hardware prevents execution in that address range. This is enabled by default on the latest Red Hat and Fedora systems if supported by the hardware. |
| SC-39 CM-6(a) |
Disable the use of user namespaces |
To set the runtime status of the user.max_user_namespaces kernel parameter,
run the following command:
$ sudo sysctl -w user.max_user_namespaces=0To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d: user.max_user_namespaces = 0When containers are deployed on the machine, the value should be set to large non-zero value. |
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or system objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. User namespaces are used primarily for Linux containers. The value 0 disallows the use of user namespaces. |
| NONE | Configure audit according to OSPP requirements |
Configure audit to meet requirements for Operating System Protection Profile (OSPP) v4.2.1.
Audit defines groups of rules in /usr/share/doc/audit/rules to satisfy specific policies.
To fulfill requirements for compliance with OSPP v4.2.1, the following files are necessary:
cp /usr/share/doc/audit*/rules/{10-base-config,11-loginuid,30-ospp-v42,43-module-load}.rules /etc/audit/rules.d/
|
The audit rules defined in /usr/share/doc/audit/rules are the recommended way to meet compliance with OSPP v4.2.1. |