| Mapping | CCE | Rule Title | Description | Rationale | Variable Setting |
| IA-2 AC-6(5) IA-4(b) |
N/A | 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(d) AU-12(c) CM-6(a) |
N/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) CM-6(a) |
N/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) CM-6(a) |
N/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) |
N/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(d) AU-12(c) CM-6(a) |
N/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(d) AU-12(c) CM-6(a) |
N/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) CM-6(a) |
N/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) |
N/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) |
N/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) |
N/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(d) AU-12(c) CM-6(a) |
N/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) CM-6(a) |
N/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) |
N/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) AC-6(9) CM-6(a) |
N/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(d) AU-12(c) AC-6(9) CM-6(a) |
N/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) |
N/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(d) AU-12(c) CM-6(a) |
N/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) CM-6(a) |
N/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) |
N/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. | |
| AU-2(d) AU-12(c) CM-6(a) |
N/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(d) AU-12(c) CM-6(a) |
N/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) |
N/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) |
N/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) |
N/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) AC-6(9) CM-6(a) |
N/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 ol8 -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 ol8 -p wa -k logins |
Manual editing of these files may indicate nefarious activity, such as an attacker attempting to remove evidence of an intrusion. | var_accounts_passwords_pam_faillock_dir=ol8 |
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
N/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) |
N/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) |
N/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) AC-6(9) CM-6(a) |
N/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) AC-6(9) CM-6(a) |
N/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) AC-6(9) CM-6(a) |
N/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(d) AU-12(c) AC-6(9) CM-6(a) |
N/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) AC-6(9) CM-6(a) |
N/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) |
N/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) AC-6(9) CM-6(a) |
N/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(d) AU-12(c) AC-6(9) CM-6(a) |
N/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. |
|
| AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
N/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) |
N/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) |
N/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) |
N/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) |
N/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) |
N/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) |
N/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 CM-8(3) IA-3 |
N/A | 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. | |
| IA-2 AC-3 CM-6(a) |
N/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. | |
| IA-2 AC-3 CM-6(a) |
N/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. | |
| 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) |
N/A | 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. |
|
| AC-2(2) AC-2(3) CM-6(a) |
N/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(4) AU-2(d) AU-12(c) AC-6(9) CM-6(a) |
N/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) |
N/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) |
N/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) |
N/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) |
N/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) |
N/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-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) |
N/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) |
N/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) |
N/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) |
N/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) |
N/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) |
N/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. | |
| SI-2(5) SI-2(c) CM-6(a) |
N/A | Ensure Software Patches Installed |
If the system is joined to the ULN
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 ULN 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. | |
| AC-2(5) AC-12 AC-17(a) SC-10 CM-6(a) |
N/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(6) CM-11(a) CM-11(b) CM-6(a) |
N/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. | |
| IA-2(11) | N/A | 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. | var_sssd_certificate_verification_digest_function=sha1 |
| AU-3 AU-3.1 AU-12(a) AU-12.1(ii) AU-12.1(iv)AU-12(c) MA-4(1)(a) |
N/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 | N/A | Enable authselect | Configure user authentication setup to use the authselect tool. If authselect profile is selected, the rule will enable the sssd 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. | var_authselect_profile=sssd |
| AC-3 AC-3(3)(a) AU-9 SC-7(21) |
N/A | 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 . |
var_selinux_policy_name=targeted |
| AC-3 AC-3(3)(a) AU-9 SC-7(21) |
N/A | 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. | var_selinux_state=enforcing |
| CM-3(5) | N/A | 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. | |
| CM-3(6) SC-12(2) SC-12(3) IA-7 SC-13 CM-6(a) SC-12 |
N/A | 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. | var_system_crypto_policy=fips |
| IA-4(e) | N/A | 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. | var_account_disable_inactivity=35 |
| IA-4(e) | N/A | 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. | var_account_disable_inactivity=35 |
| IA-4(e) AC-2(3) CM-6(a) |
N/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. | var_account_disable_post_pw_expiration=35 |
| AC-4 CM-7(b) CA-3(5) SC-7(21) CM-6(a) |
N/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. |
|
| AC-4 CM-7(b) CA-3(5) SC-7(21) CM-6(a) |
N/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. | |
| AU-4(1) | N/A | 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) | N/A | 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) | N/A | 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) | N/A | 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. | |
| IA-5(f) IA-5(1)(d) CM-6(a) |
N/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. |
var_accounts_maximum_age_login_defs=60 |
| IA-5(f) IA-5(1)(d) CM-6(a) |
N/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 1A value of 1 day is considered sufficient for many environments. The DoD requirement is 1. The profile requirement is 1. |
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. |
var_accounts_minimum_age_login_defs=1 |
| IA-5(f) IA-5(1)(a) CM-6(a) |
N/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. | var_accounts_password_minlen_login_defs=15 |
| IA-5(c) IA-5(1)(a) CM-6(a) IA-5(4) |
N/A | 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. |
|
| IA-5(c) IA-5(1)(a) CM-6(a) IA-5(4) |
N/A | 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)(b) CM-6(a) IA-5(4) |
N/A | 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. |
var_password_pam_difok=8 |
| IA-5(c) IA-5(1)(a) CM-6(a) IA-5(4) |
N/A | 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. |
|
| IA-5(c) IA-5(1)(a) CM-6(a) IA-5(4) |
N/A | 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. |
var_password_pam_maxclassrepeat=4 |
| IA-5(c) CM-6(a) IA-5(4) |
N/A | 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. |
var_password_pam_maxrepeat=3 |
| IA-5(c) IA-5(1)(a) CM-6(a) IA-5(4) |
N/A | 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 4 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. |
var_password_pam_minclass=4 |
| IA-5(c) IA-5(1)(a) CM-6(a) IA-5(4) |
N/A | 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. |
var_password_pam_minlen=15 |
| IA-5(c) IA-5(1)(a) CM-6(a) IA-5(4) |
N/A | 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. |
var_password_pam_ocredit=1 |
| IA-5(c) IA-5(1)(a) CM-6(a) IA-5(4) |
N/A | 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. |
|
| IA-5(f) IA-5(1)(d) CM-6(a) |
N/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. | var_accounts_maximum_age_login_defs=60 |
| IA-5(f) IA-5(1)(d) CM-6(a) |
N/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. | |
| AU-5(b) AU-5(2) AU-5(1) AU-5(4) CM-6(a) |
N/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) |
N/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) |
N/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. | |
| AU-5(b) AU-5(2) AU-5(1) AU-5(4) CM-6(a) |
N/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. | |
| CM-5 CM-5(6) CM-5(6).1 |
N/A | 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. | |
| SC-5 | N/A | 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(a) AU-5.1(ii) |
N/A | 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(c) IA-5(1)(c) CM-6(a) |
N/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. |
var_password_hashing_algorithm=SHA512 |
| IA-5(c) IA-5(1)(c) CM-6(a) |
N/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. |
var_password_hashing_algorithm_pam=sha512 |
| IA-5(c) IA-5(1)(c) CM-6(a) |
N/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. |
var_password_hashing_algorithm_pam=sha512 |
| IA-5 (2) (c) | N/A | 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 (2) (a) | N/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(1)(c) IA-5(1).1(v) IA-7 IA-7.1 |
N/A | 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. | |
| CM-5(1) AU-7(a) AU-7(b) AU-8(b) AU-12(3) AC-6(9) |
N/A | 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 -k setuid -a always,exit -F arch=b64 -S execve -C uid!=euid -k setuid -a always,exit -F arch=b32 -S execve -C gid!=egid -k setgid -a always,exit -F arch=b64 -S execve -C gid!=egid -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) AU-5(a) AU-5(2) CM-6(a) |
N/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. | var_auditd_action_mail_acct=root |
| IA-5(1)(a) IA-5(c) CM-6(a) |
N/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. | |
| CM-5(3) SI-7 SC-12 SC-12(3) CM-6(a) SA-12 SA-12(10) CM-11(a) CM-11(b) |
N/A | 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) |
N/A | 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) CM-11(a) CM-11(b) |
N/A | 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(6) CM-5(6).1 |
N/A | 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 |
N/A | 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 |
N/A | 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 CM-6(a) AC-6(1) |
N/A | 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 CM-6(a) AC-6(1) |
N/A | 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) |
N/A | 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 |
N/A | 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-6(a) AC-7(a) IA-5(4) |
N/A | 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. | var_password_pam_retry=3 |
| CM-6(a) AC-7(a) |
N/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. | var_accounts_passwords_pam_faillock_deny=3 |
| CM-6(a) AC-7(b) IA-5(c) |
N/A | 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(a) AC-7(a) |
N/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. | var_accounts_passwords_pam_faillock_fail_interval=900 |
| CM-6(a) AC-7(b) |
N/A | 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 never 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. | var_accounts_passwords_pam_faillock_unlock_time=never |
| CM-6(a) | N/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) CM-3(5) |
N/A | 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. |
|
| CM-6 | N/A | 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 AU-3 |
N/A | 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 AU-3 |
N/A | 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 stig 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. | var_auditd_name_format=stig |
| CM-6(a) AU-8(1)(b) AU-12(1) |
N/A | Configure Time Service Maxpoll Interval |
The maxpoll should be configured to
18_hours 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 18_hoursto 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). | var_time_service_set_maxpoll=18_hours |
| CM-6(a) MA-4(6) SC-13 SC-12(2) SC-12(3) |
N/A | 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 | N/A | 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 | N/A | 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) AC-6(1) CM-7(b) |
N/A | 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) AC-23 |
N/A | 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/local.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/local.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) | N/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) | N/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) | N/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) AC-6(1) |
N/A | 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(a) AC-6(1) |
N/A | 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) |
N/A | 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) AC-6(1) AU-9(4) |
N/A | 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/audit |
Unauthorized disclosure of audit records can reveal system and configuration data to attackers, thus compromising its confidentiality. | |
| CM-6(a) AC-6(1) AU-9(4) |
N/A | 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) AU-9 |
N/A | 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. | |
| CM-6(a) AC-6(1) CM-6(a) |
N/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(a) AC-6(1) |
N/A | 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 SC-7(10) |
N/A | 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) SC-28 SC-28(1) SC-13 AU-9(3) |
N/A | Encrypt Partitions |
Oracle 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 Oracle Linux 8 Documentation web site: https://docs.oracle.com/en/operating-systems/oracle-linux/8/install/install-InstallingOracleLinuxManually.html#system-options . |
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) AC-6(1) AU-9(4) |
N/A | 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/* |
Unauthorized disclosure of audit records can reveal system and configuration data to attackers, thus compromising its confidentiality. | |
| CM-6(a) AC-6(1) AU-9(4) |
N/A | 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) CM-5(6) CM-5(6).1 AC-6(1) |
N/A | 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) |
N/A | 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) AU-9(4) |
N/A | 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) AC-6(1) CM-7(b) |
N/A | 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. | |
| CM-6(a) | N/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) | N/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(b) CM-6.1(iv) |
N/A | 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) | N/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) | N/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) | N/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. | var_slub_debug_options=P |
| CM-6(a) | N/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. | |
| CM-6(a) | N/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) | N/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) MA-6 SA-13(a) |
N/A | The Installed Operating System Is Vendor Supported | The installed operating system must be maintained by a vendor. Oracle Linux is supported by Oracle Corporation. As the Oracle Linux vendor, Oracle Corporation 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-17(a) AC-2(5) AC-12 AC-17(a) SC-10 CM-6(a) |
N/A | Configure Logind to terminate idle sessions after certain time of inactivity |
To configure logind service to terminate inactive user sessions
after 15_minutes seconds, edit the file
/etc/systemd/logind.conf. Ensure that there is a section
[Login]which contains the configuration StopIdleSessionSec=15_minutes. |
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. | var_logind_session_timeout=15_minutes |
| CM-6(b) CM-6.1(iv) |
N/A | 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) | N/A | 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) MP-2 |
N/A | 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. | |
| AC-6 AC-6(8) AC-6(10) CM-6(a) |
N/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. | |
| AC-6 AC-6(1) CM6(a) |
N/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(b) CM-6.1(iv) |
N/A | 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-6(1) |
N/A | 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 | N/A | 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) | N/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) SI-4(22) |
N/A | 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) | N/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. Oracle 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)." | |
| CM-6(a) | N/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. |
|
| CM-6(a) | N/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) | N/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) | N/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, Oracle 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) SC-5(2) |
N/A | 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(a) SC-5(2) |
N/A | 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) SC-5(2) |
N/A | 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) AU-4 SC-5(2) |
N/A | 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) AU-4 SC-5(2) |
N/A | 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) | N/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(a) AU-4(1) AU-9(2) |
N/A | 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. | rsyslog_remote_loghost_address=logcollector |
| CM-6 | N/A | 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(a) SI-4(22) |
N/A | 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) AU-4(1) |
N/A | Enable rsyslog Service |
The rsyslog service provides syslog-style logging by default on Oracle 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) SC-8 SC-8(1) SC-8(2) SC-8(3) SC-8(4) |
N/A | 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(b) | N/A | 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. | |
| AC-6 AC-17(a) CM-6(a) |
N/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-17(a) AC-2(5) AC-12 AC-17(a) SC-10 CM-6(a) |
N/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 10_minutes 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. | sshd_idle_timeout_value=10_minutes |
| CM-6(b) | N/A | 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) IA-5(13) |
N/A | 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(b) CM-6(iv) |
N/A | 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(b) CM-6.1(iv) |
N/A | 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(a) AC-6(1) |
N/A | 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(a) AC-6(1) |
N/A | 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 | N/A | 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. | |
| AC-6 | N/A | 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. | |
| AC-6 SC-7(10) |
N/A | 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 SC-7(10) |
N/A | 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(b) | N/A | 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. | |
| CM-6(b) AC-6 CM-7(a) |
N/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. | var_tftpd_secure_directory=/var/lib/tftpboot |
| CM-6(b) | N/A | 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. | |
| AC-6(1) CM-6(a) |
N/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 077 |
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. | var_accounts_user_umask=077 |
| AC-6(1) CM-6(a) |
N/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 077 |
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. | var_accounts_user_umask=077 |
| AC-6(1) CM-6(a) |
N/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 077 |
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. | var_accounts_user_umask=077 |
| AC-6(1) CM-6(a) |
N/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 077Note 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. | var_accounts_user_umask=077 |
| AC-6(2) AC-17(a) IA-2 IA-2(5) CM-7(a) CM-7(b) CM-6(a) |
N/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) |
N/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. | |
| AC-7 (a) | N/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. | |
| AC-7 (a) | N/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. | |
| AC-7 (a) | N/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. | |
| AC-7(b) CM-6(a) |
N/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. | var_accounts_fail_delay=4 |
| AC-7 (a) | N/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. | |
| AC-7(b) AC-7(a) AC-7.1(ii) |
N/A | 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 ol8. |
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. | var_accounts_passwords_pam_faillock_dir=ol8 |
| SI-7 SI-7(1) CM-6(a) |
N/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. | |
| SI-7 SI-7(1) CM-6(a) |
N/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 (2) CM-7 (5) (b) CM-6 b |
N/A | 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) | N/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) |
N/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) |
N/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) |
N/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) MP-7 |
N/A | 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 (5) (b) |
N/A | 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) AC-6 AC-6(1) MP-7 |
N/A | 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) AC-6 AC-6(1) MP-7 |
N/A | 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 AC-6(1) MP-7 |
N/A | 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) AC-6 AC-6(1) MP-7 |
N/A | 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) AC-6 AC-6(1) MP-7 |
N/A | 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. | |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
N/A | 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) AC-6 AC-6(1) MP-7 |
N/A | 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) AC-6 AC-6(1) MP-7 |
N/A | 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) AC-6 AC-6(1) MP-7 |
N/A | 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) AC-6 AC-6(1) MP-7 |
N/A | 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) AC-6 AC-6(1) MP-7 |
N/A | 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) AC-6 AC-6(1) MP-7 |
N/A | 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. | |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
N/A | 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. | |
| CM-7(a) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
N/A | 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) AC-6 AC-6(1) MP-7 |
N/A | 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) AC-6 AC-6(1) MP-7 |
N/A | 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) CM-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
N/A | 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-7(b) CM-6(a) AC-6 AC-6(1) MP-7 |
N/A | 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) CM-7(2) MA-3 |
N/A | 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. |
|
| AC-7(a) AU-7(1) AU-7(2) AU-14 AU-12(2) AU-2(a) CM-6(a) |
N/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. | |
| IA-7 IA-7.1 |
N/A | 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 Oracle 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) IA-5(1)(c) |
N/A | 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) |
N/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) |
N/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) |
N/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) IA-5(1)(c) IA-5(1).1(v) CM-7 CM-7.1(ii) |
N/A | 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) MP-7 |
N/A | 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) |
N/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) AC-17(a) |
N/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) SC-7(a) |
N/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) SC-5 CM-6(a) SC-7(a) |
N/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) |
N/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) SC-5 CM-6(a) SC-7(a) |
N/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) SC-7(a) |
N/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) SC-5 SC-7(a) |
N/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) SC-5 CM-6(a) SC-7(a) |
N/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) SC-5 |
N/A | 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. |
|
| CM-7(a) CM-7(b) CM-6(a) |
N/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) CM-6(a) CM-6(b) CM-6.1(iv) |
N/A | 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) |
N/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) CM-6(b) CM-6.1(iv) |
N/A | 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) |
N/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) |
N/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) CM-6(b) CM-6.1(iv) |
N/A | 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. | |
| CM-7(a) CM-7(b) CM-6(a) |
N/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. | |
| CM-7(1) | N/A | 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) | N/A | 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) | N/A | 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. | |
| SC-7(10) | N/A | 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). | |
| AC-8(a) AC-8(c) |
N/A | 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(b) AC-8(c) |
N/A | 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/local.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/local.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) |
N/A | 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/local.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/local.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) |
N/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. | |
| AU-8(1) AU-12(1) |
N/A | 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 |
N/A | 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 |
N/A | 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 |
N/A | 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. | |
| AC-9 AC-9(1) |
N/A | 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 required 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. | |
| AU-9 | N/A | Audit Tools Must Be Group-owned by Root | Oracle 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 | N/A | Audit Tools Must Be Owned by Root | Oracle 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 | N/A | Audit Tools Must Have a Mode of 0755 or Less Permissive | Oracle 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. | |
| AC-9 AC-9(1) |
N/A | 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) AU-9(3).1 |
N/A | 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) |
N/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 10 |
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. | var_accounts_max_concurrent_login_sessions=10 |
| AC-11(a) AC-11(b) CM-6(a) |
N/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. | |
| AC-11(a) CM-6(a) |
N/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. | |
| AC-11(a) CM-6(a) |
N/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 5_seconds in
/etc/dconf/db/local.d/00-security-settings. For example:
[org/gnome/desktop/screensaver] lock-delay=uint32 5_secondsAfter 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. | var_screensaver_lock_delay=5_seconds |
| IA-11 | N/A | 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. | |
| CM-11(a) CM-11(b) CM-6(a) CM-5(3) SA-12 SA-12(10) |
N/A | 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. |
|
| SI-11(b) SI-11(c) SI-11.1(iv) |
N/A | 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(b) SI-11(c) SI-11.1(iv) |
N/A | 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. | |
| SI-11(b) SI-11(c) SI-11.1(iv) |
N/A | 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. | |
| IA-11 CM-6(a) |
N/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. |
|
| IA-11 CM-6(a) |
N/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. |
|
| IA-11 | N/A | 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. |
|
| SI-11(a) SI-11(b) |
N/A | 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. | |
| AU-12(b) | N/A | 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. | |
| AU-12(b) | N/A | 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. | |
| SC-12(2) SC-12(3) IA-7 SC-13 CM-6(a) SC-12 |
N/A | 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) IA-7 SC-13 CM-6(a) SC-12 |
N/A | 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-13 SC-12(2) SC-12(3) |
N/A | 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) |
N/A | 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 | N/A | 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) |
N/A | Configure System Cryptography Policy |
To configure the system cryptography policy to use ciphers only from the fips
policy, run the following command:
$ sudo update-crypto-policies --set fipsThe 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. | var_system_crypto_policy=fips |
| AC-17(a) AC-17(2) CM-6(a) MA-4(6) SC-13 SC-12(2) SC-12(3) |
N/A | 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) AC-17(2) CM-6(a) MA-4(6) SC-13 |
N/A | 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 (1) | N/A | Firewalld Must Employ a Deny-all, Allow-by-exception Policy for Allowing Connections to Other Systems | Oracle 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) |
N/A | 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(a) AC-6(1) |
N/A | 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) CM-7(a) CM-7(b) CM-6(a) |
N/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(a) CM-7(a) CM-7(b) CM-6(a) |
N/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(a) CM-7(a) CM-7(b) CM-6(a) |
N/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-7(a) CM-7(b) CM-6(a) |
N/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(1) AU-14(1) AU-10 CM-6(a) IR-5(1) |
N/A | 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) | N/A | 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) | N/A | 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) | N/A | 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) | N/A | 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 stig_extended |
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. | sshd_approved_ciphers=stig_extended |
| AC-17(2) | N/A | 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=stig_extended |
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. | sshd_approved_ciphers=stig_extended |
| AC-17(2) | N/A | 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 stig_extended | Overriding the system crypto policy makes the behavior of the OpenSSH client violate expectations, and makes system configuration more fragmented. | sshd_approved_macs=stig_extended |
| AC-17(2) | N/A | 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=stig_extended | Overriding the system crypto policy makes the behavior of the OpenSSH server violate expectations, and makes system configuration more fragmented. | sshd_approved_macs=stig_extended |
| AC-17(2) | N/A | 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-18 | N/A | 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 |
N/A | 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 | N/A | 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 | N/A | 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(a) AC-18(3) CM-7(a) CM-7(b) CM-6(a) MP-7 |
N/A | 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. | |
| SC-20(a) CM-6(a) |
N/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-30 SC-30(2) SC-30(5) CM-6(a) |
N/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. | sysctl_kernel_kptr_restrict_value=1 |
| SC-30 SC-30(2) CM-6(a) |
N/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-39 CM-6(a) |
N/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) |
N/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. | |
| N/A | Ensure All Accounts on the System Have Unique User IDs | Change user IDs (UIDs), or delete accounts, so each has a unique name. | To assure accountability and prevent unauthenticated access, interactive users must be identified and authenticated to prevent potential misuse and compromise of the system. | ||
| N/A | Only Authorized Local User Accounts Exist on Operating System |
Enterprise Application tends to use the server or virtual machine exclusively.
Besides the default operating system user, there should be only authorized local
users required by the installed software groups and applications that exist on
the operating system. The authorized user list can be customized in the refine
value variable var_accounts_authorized_local_users_regex.
OVAL regular expression is used for the user list.
Configure the system so all accounts on the system are assigned to an active system,
application, or user account. Remove accounts that do not support approved system
activities or that allow for a normal user to perform administrative-level actions.
To remove unauthorized system accounts, use the following command:
$ sudo userdel unauthorized_user |
Accounts providing no operational purpose provide additional opportunities for system compromise. Unnecessary accounts include user accounts for individuals not requiring access to the system and application accounts for applications not installed on the system. | ||
| N/A | Ensure Home Directories are Created for New Users |
All local interactive user accounts, upon creation, should be assigned a home directory.
Configure the operating system to assign home directories to all new local interactive users by setting the CREATE_HOME parameter in /etc/login.defs to yes as follows: CREATE_HOME yes |
If local interactive users are not assigned a valid home directory, there is no place for the storage and control of files they should own. | ||
| N/A | Ensure PAM password complexity module is enabled in password-auth | To enable PAM password complexity in password-auth file: Edit the password section in /etc/pam.d/password-auth to show password requisite pam_pwquality.so. | Enabling PAM password complexity permits to enforce strong passwords and consequently makes the system less prone to dictionary attacks. | ||
| N/A | Ensure PAM password complexity module is enabled in system-auth | To enable PAM password complexity in system-auth file: Edit the password section in /etc/pam.d/system-auth to show password requisite pam_pwquality.so. | Enabling PAM password complexity permits to enforce strong passwords and consequently makes the system less prone to dictionary attacks. | ||
| N/A | Do Not Show System Messages When Unsuccessful Logon Attempts Occur | This rule ensures the system prevents informative messages from being presented to the user pertaining to logon information 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. | The pam_faillock module without the silent option will leak information about the existence or non-existence of a user account in the system because the failures are not recorded for unknown users. The message about the user account being locked is never displayed for non-existing user accounts allowing the adversary to infer that a particular account exists or not on the system. | ||
| N/A | Ensure the Default Umask is Set Correctly For Interactive Users | Remove the UMASK environment variable from all interactive users initialization files. | The umask controls the default access mode assigned to newly created files. A umask of 077 limits new files to mode 700 or less permissive. Although umask can be represented as a four-digit number, the first digit representing special access modes is typically ignored or required to be 0. This requirement applies to the globally configured system defaults and the local interactive user defaults for each account on the system. | ||
| N/A | User Initialization Files Must Not Run World-Writable Programs |
Set the mode on files being executed by the user initialization files with the
following command:
$ sudo chmod o-w FILE |
If user start-up files execute world-writable programs, especially in unprotected directories, they could be maliciously modified to destroy user files or otherwise compromise the system at the user level. If the system is compromised at the user level, it is easier to elevate privileges to eventually compromise the system at the root and network level. | ||
| N/A | Ensure that Users Path Contains Only Local Directories | Ensure that all interactive user initialization files executable search path statements do not contain statements that will reference a working directory other than the users home directory. | The executable search path (typically the PATH environment variable) contains a list of directories for the shell to search to find executables. If this path includes the current working directory (other than the users home directory), executables in these directories may be executed instead of system commands. This variable is formatted as a colon-separated list of directories. If there is an empty entry, such as a leading or trailing colon or two consecutive colons, this is interpreted as the current working directory. If deviations from the default system search path for the local interactive user are required, they must be documented with the Information System Security Officer (ISSO). | ||
| N/A | All Interactive Users Must Have A Home Directory Defined | Assign home directories to all interactive users that currently do not have a home directory assigned. This rule checks if the home directory is properly defined in a folder which has at least one parent folder, like "user" in "/home/user" or "/remote/users/user". Therefore, this rule will report a finding for home directories like /users, /tmp or /. | If local interactive users are not assigned a valid home directory, there is no place for the storage and control of files they should own. | ||
| N/A | All Interactive Users Home Directories Must Exist |
Create home directories to all local interactive users that currently do not
have a home directory assigned. Use the following commands to create the user
home directory assigned in /etc/passwd:
$ sudo mkdir /home/USER |
If a local interactive user has a home directory defined that does not exist, the user may be given access to the / directory as the current working directory upon logon. This could create a Denial of Service because the user would not be able to access their logon configuration files, and it may give them visibility to system files they normally would not be able to access. | ||
| N/A | All User Files and Directories In The Home Directory Must Be Group-Owned By The Primary Group |
Change the group of a local interactive users files and directories to a
group that the interactive user is a member of. To change the group owner of a
local interactive users files and directories, use the following command:
$ sudo chgrp USER_GROUP /home/USER/FILE_DIRThis rule ensures every file or directory under the home directory related to an interactive user is group-owned by an interactive user. |
If a local interactive users files are group-owned by a group of which the user is not a member, unintended users may be able to access them. | ||
| N/A | All User Files and Directories In The Home Directory Must Have Mode 0750 Or Less Permissive |
Set the mode on files and directories in the local interactive user home
directory with the following command:
$ sudo chmod 0750 /home/USER/FILE_DIRFiles that begin with a "." are excluded from this requirement. |
If a local interactive user files have excessive permissions, unintended users may be able to access or modify them. | ||
| N/A | Record Any Attempts to Run chacl |
At a minimum, the audit system should collect any execution attempt
of the chacl 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/chacl -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/chacl -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). | ||
| N/A | Record Any Attempts to Run setfacl |
At a minimum, the audit system should collect any execution attempt
of the setfacl 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/setfacl -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/setfacl -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). | ||
| N/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.
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 login UIDs
immutable:
--loginuid-immutableIf 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 login UIDs immutable: --loginuid-immutable |
If modification of login UIDs is not prevented, they can be changed by unprivileged users and make auditing complicated or impossible. | ||
| N/A | Record Any Attempts to Run ssh-agent |
At a minimum, the audit system should collect any execution attempt
of the ssh-agent 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/ssh-agent -F perm=x -F auid>=1000 -F auid!=unset -k privileged-ssh-agentIf 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/ssh-agent -F perm=x -F auid>=1000 -F auid!=unset -k privileged-ssh-agent |
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). | ||
| N/A | Ensure auditd Collects Information on the Use of Privileged Commands - unix_update |
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_update -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_update -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. |
||
| N/A | Ensure auditd Collects Information on the Use of Privileged Commands - usermod |
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/usermod -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/usermod -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. |
||
| N/A | Ensure auditd Collects System Administrator Actions - /etc/sudoers |
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 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 |
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. Editing the sudoers file may be sign of an attacker trying to establish persistent methods to a system, auditing the editing of the sudoers files mitigates this risk. | ||
| N/A | Ensure auditd Collects System Administrator Actions - /etc/sudoers.d/ |
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.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.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. Editing the sudoers file may be sign of an attacker trying to establish persistent methods to a system, auditing the editing of the sudoers files mitigates this risk. | ||
| N/A | Configure a Sufficiently Large Partition for Audit Logs |
The Oracle Linux 8 operating system must allocate audit record storage
capacity to store at least one weeks worth of audit records when audit
records are not immediately sent to a central audit record storage
facility.
The partition size needed to capture a week's worth of audit records is
based on the activity level of the system and the total storage capacity
available.
In normal circumstances, 10.0 GB of storage space for audit
records will be sufficient.
Determine which partition the audit records are being written to with the
following command:
$ sudo grep log_file /etc/audit/auditd.conf log_file = /var/log/audit/audit.logCheck the size of the partition that audit records are written to with the following command: $ sudo df -h /var/log/audit/ /dev/sda2 24G 10.4G 13.6G 43% /var/log/audit |
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. | ||
| N/A | Ensure Chrony is only configured with the server directive | Check that Chrony only has time sources configured with the server directive. | Depending on the infrastructure being used the pool directive may not be supported. Using the server directive allows for better control of where the system gets time data from. | ||
| N/A | Support session locking with tmux (not enforcing) | The tmux terminal multiplexer is used to implement automatic session locking. It should be started from /etc/bashrc or drop-in files within /etc/profile.d/. | Unlike bash itself, the tmux terminal multiplexer provides a mechanism to lock sessions after period of inactivity. 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 log out because of the temporary nature of the absence. | ||
| N/A | Configure tmux to lock session after inactivity | To enable console screen locking in tmux terminal multiplexer after a period of inactivity, the lock-after-time option has to be set to a value greater than 0 and less than or equal to 900 in /etc/tmux.conf. | Locking the session after a period of inactivity limits the potential exposure if the session is left unattended. | ||
| N/A | Configure the tmux lock session key binding |
To set a key binding for the screen locking in tmux terminal multiplexer,
the session-lock command must be bound to a key.
Add the following line to /etc/tmux.conf:
bind X lock-session. The console can now be locked with the following key combination: Ctrl+b Shift+x |
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. | ||
| N/A | Enable the GNOME3 Screen Locking On Smartcard Removal |
In the default graphical environment, screen locking on smartcard removal
can be enabled by setting removal-action
to 'lock-screen'.
To enable, add or edit removal-action to /etc/dconf/db/local.d/00-security-settings. For example: [org/gnome/settings-daemon/peripherals/smartcard] removal-action='lock-screen'Once 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/settings-daemon/peripherals/smartcard/removal-actionAfter the settings have been set, run dconf update. |
Locking the screen automatically when removing the smartcard can prevent undesired access to system. | ||
| N/A | Verify Group Who Owns /var/log Directory |
To properly set the group owner of /var/log, run the command: $ sudo chgrp root /var/log |
The /var/log directory contains files with logs of error messages in the system and should only be accessed by authorized personnel. | ||
| N/A | Verify Group Who Owns /var/log/messages File |
To properly set the group owner of /var/log/messages, run the command: $ sudo chgrp root /var/log/messages |
The /var/log/messages file contains logs of error messages in the system and should only be accessed by authorized personnel. | ||
| N/A | All Interactive User Home Directories Must Be Group-Owned By The Primary Group |
Change the group owner of interactive users home directory to the
group found in /etc/passwd. To change the group owner of
interactive users home directory, use the following command:
$ sudo chgrp USER_GROUP /home/USERThis rule ensures every home directory related to an interactive user is group-owned by an interactive user. It also ensures that interactive users are group-owners of one and only one home directory. |
If the Group Identifier (GID) of a local interactive users home directory is not the same as the primary GID of the user, this would allow unauthorized access to the users files, and users that share the same group may not be able to access files that they legitimately should. | ||
| N/A | Verify User Who Owns /var/log Directory |
To properly set the owner of /var/log, run the command: $ sudo chown root /var/log |
The /var/log directory contains files with logs of error messages in the system and should only be accessed by authorized personnel. | ||
| N/A | Verify User Who Owns /var/log/messages File |
To properly set the owner of /var/log/messages, run the command: $ sudo chown root /var/log/messages |
The /var/log/messages file contains logs of error messages in the system and should only be accessed by authorized personnel. | ||
| N/A | Ensure All User Initialization Files Have Mode 0740 Or Less Permissive |
Set the mode of the user initialization files to 0740 with the
following command:
$ sudo chmod 0740 /home/USER/.INIT_FILE |
Local initialization files are used to configure the user's shell environment upon logon. Malicious modification of these files could compromise accounts upon logon. | ||
| N/A | All Interactive User Home Directories Must Have mode 0750 Or Less Permissive |
Change the mode of interactive users home directories to 0750. To
change the mode of interactive users home directory, use the
following command:
$ sudo chmod 0750 /home/USER |
Excessive permissions on local interactive user home directories may allow unauthorized access to user files by other users. | ||
| N/A | Verify Permissions on /var/log Directory |
To properly set the permissions of /var/log, run the command:
$ sudo chmod 0755 /var/log |
The /var/log directory contains files with logs of error messages in the system and should only be accessed by authorized personnel. | ||
| N/A | Verify Permissions on /var/log/messages File |
To properly set the permissions of /var/log/messages, run the command:
$ sudo chmod 0640 /var/log/messages |
The /var/log/messages file contains logs of error messages in the system and should only be accessed by authorized personnel. | ||
| N/A | Disable Kerberos by removing host keytab | Kerberos is not an approved key distribution method for Common Criteria. To prevent using Kerberos by system daemons, remove the Kerberos keytab files, especially /etc/krb5.keytab. | The key derivation function (KDF) in Kerberos is not FIPS compatible. | ||
| N/A | Add nodev Option to /var/tmp |
The nodev mount option can be used to prevent device files from
being created in /var/tmp. Legitimate character and block devices
should not exist within temporary directories like /var/tmp.
Add the nodev option to the fourth column of
/etc/fstab for the line which controls mounting of
/var/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. | ||
| N/A | Add noexec Option to /var/tmp |
The noexec mount option can be used to prevent binaries
from being executed out of /var/tmp.
Add the noexec option to the fourth column of
/etc/fstab for the line which controls mounting of
/var/tmp.
|
Allowing users to execute binaries from world-writable directories such as /var/tmp should never be necessary in normal operation and can expose the system to potential compromise. | ||
| N/A | Add nosuid Option to /var/tmp |
The nosuid mount option can be used to prevent
execution of setuid programs in /var/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
/var/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. | ||
| N/A | Remove Host-Based Authentication Files |
The shosts.equiv file lists remote hosts and users that are trusted by the local
system. To remove these files, run the following command to delete them from any location:
$ sudo rm /[path]/[to]/[file]/shosts.equiv |
The shosts.equiv files are used to configure host-based authentication for the system via SSH. Host-based authentication is not sufficient for preventing unauthorized access to the system, as it does not require interactive identification and authentication of a connection request, or for the use of two-factor authentication. | ||
| N/A | Remove User Host-Based Authentication Files |
The ~/.shosts (in each user's home directory) files
list remote hosts and users that are trusted by the
local system. To remove these files, run the following command
to delete them from any location:
$ sudo find / -name '.shosts' -type f -delete |
The .shosts files are used to configure host-based authentication for individual users or the system via SSH. Host-based authentication is not sufficient for preventing unauthorized access to the system, as it does not require interactive identification and authentication of a connection request, or for the use of two-factor authentication. | ||
| N/A | Uninstall abrt-libs Package |
The abrt-libs package can be removed with the following command:
$ sudo yum erase abrt-libs |
abrt-libs provides libraries for the ABRT package. | ||
| N/A | Uninstall abrt-server-info-page Package |
The abrt-server-info-page package can be removed with the following command:
$ sudo yum erase abrt-server-info-page |
abrt-server-info-page provides a web page with summary of ABRT services. | ||
| N/A | Uninstall Automatic Bug Reporting Tool (abrt) |
The Automatic Bug Reporting Tool (abrt) collects
and reports crash data when an application crash is detected. Using a variety
of plugins, abrt 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 abrt package can be removed with the following command:
$ sudo yum erase abrt |
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. | ||
| N/A | Uninstall gssproxy Package |
The gssproxy package can be removed with the following command:
$ sudo yum erase gssproxy |
gssproxy is a proxy for GSS API credential handling. | ||
| N/A | Uninstall iprutils Package |
The iprutils package can be removed with the following command:
$ sudo yum erase iprutils |
iprutils provides a suite of utlilities to manage and configure SCSI devices supported by the ipr SCSI storage device driver. | ||
| N/A | Uninstall krb5-workstation Package |
The krb5-workstation package can be removed with the following command:
$ sudo yum erase krb5-workstation |
Kerberos is a network authentication system. The krb5-workstation package contains the basic Kerberos programs (kinit, klist, kdestroy, kpasswd). | ||
| N/A | Uninstall libreport-plugin-logger Package |
The libreport-plugin-logger package can be removed with the following command:
$ sudo yum erase libreport-plugin-logger |
libreport-plugin-logger is a ABRT plugin to report bugs into the Oracle Linux Support system. | ||
| N/A | Install policycoreutils Package |
The policycoreutils package can be installed with the following command:
$ sudo yum install policycoreutils |
Security-enhanced Linux is a feature of the Linux kernel and a number of utilities with enhanced security functionality designed to add mandatory access controls to Linux. The Security-enhanced Linux kernel contains new architectural components originally developed to improve security of the Flask operating system. These architectural components provide general support for the enforcement of many kinds of mandatory access control policies, including those based on the concepts of Type Enforcement, Role-based Access Control, and Multi-level Security. policycoreutils contains the policy core utilities that are required for basic operation of an SELinux-enabled system. These utilities include load_policy to load SELinux policies, setfiles to label filesystems, newrole to switch roles, and so on. | ||
| N/A | Install rng-tools Package |
The rng-tools package can be installed with the following command:
$ sudo yum install rng-tools |
rng-tools provides hardware random number generator tools, such as those used in the formation of x509/PKI certificates. | ||
| N/A | Ensure rsyslog-gnutls is installed |
TLS protocol support for rsyslog is installed.
The rsyslog-gnutls package can be installed with the following command:
$ sudo yum install rsyslog-gnutls |
The rsyslog-gnutls package provides Transport Layer Security (TLS) support for the rsyslog daemon, which enables secure remote logging. | ||
| N/A | Uninstall tuned Package |
The tuned package can be removed with the following command:
$ sudo yum erase tuned |
tuned contains a daemon that tunes the system settings dynamically. It does so by monitoring the usage of several system components periodically. Based on that information, components will then be put into lower or higher power savings modes to adapt to the current usage. | ||
| N/A | Ensure /var/tmp Located On Separate Partition | The /var/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 /var/tmp partition is used as temporary storage by many programs. Placing /var/tmp in its own partition enables the setting of more restrictive mount options, which can help protect programs which use it. | ||
| N/A | Prevent Unrestricted Mail Relaying |
Modify the /etc/postfix/main.cffile to restrict client connections to the local network with the following command: $ sudo postconf -e 'smtpd_client_restrictions = permit_mynetworks,reject' |
If unrestricted mail relaying is permitted, unauthorized senders could use this host as a mail relay for the purpose of sending spam or other unauthorized activity. | ||
| N/A | Map System Users To The Appropriate SELinux Role |
Configure the operating system to prevent non-privileged users from executing
privileged functions to include disabling, circumventing, or altering
implemented security safeguards/countermeasures. All administrators must be
mapped to the sysadm_u or staff_u users with the
appropriate domains (sysadm_t and staff_t).
$ sudo semanage login -m -s sysadm_u USERor $ sudo semanage login -m -s staff_u USER All authorized non-administrative users must be mapped to the user_u role or the appropriate domain (user_t). $ sudo semanage login -m -s user_u USER |
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. |
||
| N/A | Enable the Hardware RNG Entropy Gatherer Service |
The Hardware RNG Entropy Gatherer service should be enabled.
The rngd service can be enabled with the following command:
$ sudo systemctl enable rngd.service |
The rngd service feeds random data from hardware device to kernel random device. | ||
| N/A | Set Password Hashing Rounds in /etc/login.defs |
In /etc/login.defs, ensure SHA_CRYPT_MIN_ROUNDS and
SHA_CRYPT_MAX_ROUNDS has the minimum value of 5000.
For example:
SHA_CRYPT_MIN_ROUNDS 5000 SHA_CRYPT_MAX_ROUNDS 5000Notice that if neither are set, they already have the default value of 5000. If either is set, they must have the minimum value of 5000. |
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 more hashing rounds makes password cracking attacks more difficult. |
||
| N/A | Verify the SSH Private Key Files Have a Passcode |
When creating SSH key pairs, always use a passcode.
You can create such keys with the following command: $ sudo ssh-keygen -n [passphrase]Oracle Linux 8, for certificate-based authentication, must enforce authorized access to the corresponding private key. |
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. | ||
| N/A | Force frequent session key renegotiation |
The RekeyLimit parameter specifies how often
the session key of the is renegotiated, both in terms of
amount of data that may be transmitted and the time
elapsed. To decrease the default limits, add or correct the following line in /etc/ssh/sshd_config: RekeyLimit 1G 1hour |
By decreasing the limit based on the amount of data and enabling time-based limit, effects of potential attacks against encryption keys are limited. | var_rekey_limit_size=1G var_rekey_limit_time=1hour |
|
| N/A | SSH server uses strong entropy to seed |
To set up SSH server to use entropy from a high-quality source, edit the /etc/sysconfig/sshd file.
The SSH_USE_STRONG_RNG configuration value determines how many bytes of entropy to use, so
make sure that the file contains line
SSH_USE_STRONG_RNG=32 |
SSH implementation in Oracle Linux 8 uses the openssl library, which doesn't use high-entropy sources by default. Randomness is needed to generate data-encryption keys, and as plaintext padding and initialization vectors in encryption algorithms, and high-quality entropy elliminates the possibility that the output of the random number generator used by SSH would be known to potential attackers. | ||
| N/A | Enable Smartcards in SSSD |
SSSD should be configured to authenticate access to the system using smart cards.
To enable smart cards in SSSD, set pam_cert_auth to True under the
[pam] section in /etc/sssd/sssd.conf. For example:
[pam] pam_cert_auth = TrueAdd or update "pam_sss.so" line in auth section of "/etc/pam.d/system-auth" file to include "try_cert_auth" or "require_cert_auth" option, like in the following example: /etc/pam.d/system-auth:auth [success=done authinfo_unavail=ignore ignore=ignore default=die] pam_sss.so try_cert_authAlso add or update "pam_sss.so" line in auth section of "/etc/pam.d/smartcard-auth" file to include the "allow_missing_name" option, like in the following example: /etc/pam.d/smartcard-auth:auth sufficient pam_sss.so allow_missing_name |
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.
Multi-Factor Authentication (MFA) 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. |
||
| N/A | Ensure sudo only includes the default configuration directory | Administrators can configure authorized sudo users via drop-in files, and it is possible to include other directories and configuration files from the file currently being parsed. Make sure that /etc/sudoers only includes drop-in configuration files from /etc/sudoers.d, or that no drop-in file is included. Either the /etc/sudoers should contain only one #includedir directive pointing to /etc/sudoers.d, and no file in /etc/sudoers.d/ should include other files or directories; Or the /etc/sudoers should not contain any #include, @include, #includedir or @includedir directives. Note that the '#' character doesn't denote a comment in the configuration file. | Some sudo configurtion options allow users to run programs without re-authenticating. Use of these configuration options makes it easier for one compromised accound to be used to compromise other accounts. | ||
| N/A | Check that vlock is installed to allow session locking |
The Oracle Linux 8 operating system must have vlock installed to allow for session locking.
The kbd package can be installed with the following command:
$ sudo yum install kbd |
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 log out because of the temporary nature of the absence. The session lock is implemented at the point where session activity can be determined. Regardless of where the session lock is determined and implemented, once invoked, the session lock must remain in place until the user reauthenticates. No other activity aside from reauthentication must unlock the system. |