Guide to the Secure Configuration of Fedora

with profile CUSP - Common User Security Profile for Fedora Workstation
This profile contains rules to harden Fedora Linux according to the Common User Security Guide for Fedora Workstation.

The SCAP Security Guide Project
https://www.open-scap.org/security-policies/scap-security-guide

This guide presents a catalog of security-relevant configuration settings for Fedora. It is a rendering of content structured in the eXtensible Configuration Checklist Description Format (XCCDF) in order to support security automation. The SCAP content is is available in the scap-security-guide package which is developed at https://www.open-scap.org/security-policies/scap-security-guide.

Providing system administrators with such guidance informs them how to securely configure systems under their control in a variety of network roles. Policy makers and baseline creators can use this catalog of settings, with its associated references to higher-level security control catalogs, in order to assist them in security baseline creation. This guide is a catalog, not a checklist, and satisfaction of every item is not likely to be possible or sensible in many operational scenarios. However, the XCCDF format enables granular selection and adjustment of settings, and their association with OVAL and OCIL content provides an automated checking capability. Transformations of this document, and its associated automated checking content, are capable of providing baselines that meet a diverse set of policy objectives. Some example XCCDF Profiles, which are selections of items that form checklists and can be used as baselines, are available with this guide. They can be processed, in an automated fashion, with tools that support the Security Content Automation Protocol (SCAP). The DISA STIG, which provides required settings for US Department of Defense systems, is one example of a baseline created from this guidance.

Do not attempt to implement any of the settings in this guide without first testing them in a non-operational environment. The creators of this guidance assume no responsibility whatsoever for its use by other parties, and makes no guarantees, expressed or implied, about its quality, reliability, or any other characteristic.

Profile Information

Profile Title	CUSP - Common User Security Profile for Fedora Workstation
Profile ID	xccdf_org.ssgproject.content_profile_cusp_fedora

CPE Platforms

cpe:/o:fedoraproject:fedora:39
cpe:/o:fedoraproject:fedora:40
cpe:/o:fedoraproject:fedora:41
cpe:/o:fedoraproject:fedora:42
cpe:/o:fedoraproject:fedora:43
cpe:/o:fedoraproject:fedora:44
cpe:/o:fedoraproject:fedora:45

Revision History

Current version: 0.1.76

draft (as of 2024-11-29)

System Settings
Services
System Accounting with auditd
1. Configure auditd Rules for Comprehensive Auditing
2. Configure auditd Data Retention

Checklist

Group Guide to the Secure Configuration of Fedora Group contains 93 groups and 272 rules

Group System Settings Group contains 43 groups and 133 rules

[ref] Contains rules that check correct system settings.

Group Installing and Maintaining Software Group contains 6 groups and 16 rules

[ref] The following sections contain information on security-relevant choices during the initial operating system installation process and the setup of software updates.

Group System and Software Integrity Group contains 1 group and 7 rules

[ref] System and software integrity can be gained by installing antivirus, increasing system encryption strength with FIPS, verifying installed software, enabling SELinux, installing an Intrusion Prevention System, etc. However, installing or enabling integrity checking tools cannot prevent intrusions, but they can detect that an intrusion may have occurred. Requirements for integrity checking may be highly dependent on the environment in which the system will be used. Snapshot-based approaches such as AIDE may induce considerable overhead in the presence of frequent software updates.

Group System Cryptographic Policies Group contains 7 rules

[ref] Linux has the capability to centrally configure cryptographic polices. The command update-crypto-policies is used to set the policy applicable for the various cryptographic back-ends, such as SSL/TLS libraries. The configured cryptographic policies will be the default policy used by these backends unless the application user configures them otherwise. When the system has been configured to use the centralized cryptographic policies, the administrator is assured that any application that utilizes the supported backends will follow a policy that adheres to the configured profile. Currently the supported backends are:

GnuTLS library
OpenSSL library
NSS library
OpenJDK
Libkrb5
BIND
OpenSSH

Applications and languages which rely on any of these backends will follow the system policies as well. Examples are apache httpd, nginx, php, and others.

Rule Configure BIND to use System Crypto Policy [ref]

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";

Rationale:

Overriding the system crypto policy makes the behavior of the BIND service violate expectations, and makes system configuration more fragmented.

Severity:

high

Rule ID: xccdf_org.ssgproject.content_rule_configure_bind_crypto_policy

References:

disa	CCI-002418, CCI-002422
nerc-cip	CIP-003-8 R4.2, CIP-007-3 R5.1
nist	SC-13, SC-12(2), SC-12(3)
os-srg	SRG-OS-000423-GPOS-00187, SRG-OS-000426-GPOS-00190

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-53-SC-12(2)
  - NIST-800-53-SC-12(3)
  - NIST-800-53-SC-13
  - configure_bind_crypto_policy
  - configure_strategy
  - high_severity
  - low_complexity
  - low_disruption
  - no_reboot_needed

- name: Configure BIND to use System Crypto Policy - Check BIND configuration file
    exists
  ansible.builtin.stat:
    path: /etc/named.conf
  register: bind_config_file
  when: '"bind" in ansible_facts.packages'
  tags:
  - NIST-800-53-SC-12(2)
  - NIST-800-53-SC-12(3)
  - NIST-800-53-SC-13
  - configure_bind_crypto_policy
  - configure_strategy
  - high_severity
  - low_complexity
  - low_disruption
  - no_reboot_needed

- name: Configure BIND to use System Crypto Policy - Aborting remediation, file not
    found
  ansible.builtin.debug:
    msg: Aborting remediation as '/etc/named.conf' was not found.
  when:
  - '"bind" in ansible_facts.packages'
  - not bind_config_file.stat.exists
  tags:
  - NIST-800-53-SC-12(2)
  - NIST-800-53-SC-12(3)
  - NIST-800-53-SC-13
  - configure_bind_crypto_policy
  - configure_strategy
  - high_severity
  - low_complexity
  - low_disruption
  - no_reboot_needed

- name: Configure BIND to use System Crypto Policy - Insert crypto-policy into BIND
    config
  ansible.builtin.lineinfile:
    path: /etc/named.conf
    insertafter: ^\s*options\s*{
    line: ' include "/etc/crypto-policies/back-ends/bind.config";'
    state: present
  when:
  - '"bind" in ansible_facts.packages'
  - bind_config_file.stat.exists
  tags:
  - NIST-800-53-SC-12(2)
  - NIST-800-53-SC-12(3)
  - NIST-800-53-SC-13
  - configure_bind_crypto_policy
  - configure_strategy
  - high_severity
  - low_complexity
  - low_disruption
  - no_reboot_needed

Remediation Shell script ⇲

# Remediation is applicable only in certain platforms
if rpm --quiet -q bind; then

function remediate_bind_crypto_policy() {
	CONFIG_FILE="/etc/named.conf"
	if test -f "$CONFIG_FILE"; then
		sed -i 's|options {|&\n\tinclude "/etc/crypto-policies/back-ends/bind.config";|' "$CONFIG_FILE"
		return 0
	else
		echo "Aborting remediation as '$CONFIG_FILE' was not even found." >&2
		return 1
	fi
}

remediate_bind_crypto_policy

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Configure System Cryptography Policy [ref]

To configure the system cryptography policy to use ciphers only from the DEFAULT policy, run the following command:

$ sudo update-crypto-policies --set DEFAULT

The 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.

Warning: The system needs to be rebooted for these changes to take effect.

Warning: System Crypto Modules must be provided by a vendor that undergoes FIPS-140 certifications. FIPS-140 is applicable to all Federal agencies that use cryptographic-based security systems to protect sensitive information in computer and telecommunication systems (including voice systems) as defined in Section 5131 of the Information Technology Management Reform Act of 1996, Public Law 104-106. This standard shall be used in designing and implementing cryptographic modules that Federal departments and agencies operate or are operated for them under contract. See https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.140-2.pdf To meet this, the system has to have cryptographic software provided by a vendor that has undergone this certification. This means providing documentation, test results, design information, and independent third party review by an accredited lab. While open source software is capable of meeting this, it does not meet FIPS-140 unless the vendor submits to this process.

Rationale:

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.

Severity:

high

Rule ID: xccdf_org.ssgproject.content_rule_configure_crypto_policy

References:

disa	CCI-000068, CCI-003123, CCI-002450, CCI-000877, CCI-002418, CCI-001453, CCI-002890
hipaa	164.308(a)(4)(i), 164.308(b)(1), 164.308(b)(3), 164.312(e)(1), 164.312(e)(2)(ii)
ism	1446
nerc-cip	CIP-003-8 R4.2, CIP-007-3 R5.1, CIP-007-3 R7.1
nist	AC-17(a), AC-17(2), CM-6(a), MA-4(6), SC-13, SC-12(2), SC-12(3)
ospp	FCS_COP.1(1), FCS_COP.1(2), FCS_COP.1(3), FCS_COP.1(4), FCS_CKM.1, FCS_CKM.2, FCS_TLSC_EXT.1
os-srg	SRG-OS-000396-GPOS-00176, SRG-OS-000393-GPOS-00173, SRG-OS-000394-GPOS-00174
pcidss4	2.2.7, 2.2

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: XCCDF Value var_system_crypto_policy # promote to variable
  set_fact:
    var_system_crypto_policy: !!str DEFAULT
  tags:
    - always

- name: Configure System Cryptography Policy
  lineinfile:
    path: /etc/crypto-policies/config
    regexp: ^(?!#)(\S+)$
    line: '{{ var_system_crypto_policy }}'
    create: true
  tags:
  - NIST-800-53-AC-17(2)
  - NIST-800-53-AC-17(a)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-MA-4(6)
  - NIST-800-53-SC-12(2)
  - NIST-800-53-SC-12(3)
  - NIST-800-53-SC-13
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.7
  - configure_crypto_policy
  - high_severity
  - low_complexity
  - low_disruption
  - no_reboot_needed
  - restrict_strategy

- name: Verify that Crypto Policy is Set (runtime)
  command: /usr/bin/update-crypto-policies --set {{ var_system_crypto_policy }}
  tags:
  - NIST-800-53-AC-17(2)
  - NIST-800-53-AC-17(a)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-MA-4(6)
  - NIST-800-53-SC-12(2)
  - NIST-800-53-SC-12(3)
  - NIST-800-53-SC-13
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.7
  - configure_crypto_policy
  - high_severity
  - low_complexity
  - low_disruption
  - no_reboot_needed
  - restrict_strategy

Remediation Kubernetes snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	true
Strategy:	restrict

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    systemd:
      units:
        - name: configure-crypto-policy.service
          enabled: true
          contents: |
            [Unit]
            Before=kubelet.service
            [Service]
            Type=oneshot
            ExecStart=update-crypto-policies --set {{.var_system_crypto_policy}}
            RemainAfterExit=yes
            [Install]
            WantedBy=multi-user.target

Remediation Shell script ⇲


var_system_crypto_policy='DEFAULT'


stderr_of_call=$(update-crypto-policies --set ${var_system_crypto_policy} 2>&1 > /dev/null)
rc=$?

if test "$rc" = 127; then
	echo "$stderr_of_call" >&2
	echo "Make sure that the script is installed on the remediated system." >&2
	echo "See output of the 'dnf provides update-crypto-policies' command" >&2
	echo "to see what package to (re)install" >&2

	false  # end with an error code
elif test "$rc" != 0; then
	echo "Error invoking the update-crypto-policies script: $stderr_of_call" >&2
	false  # end with an error code
fi

Rule Configure GnuTLS library to use DoD-approved TLS Encryption [ref]

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

Rationale:

Overriding the system crypto policy makes the behavior of the GnuTLS library violate expectations, and makes system configuration more fragmented.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_configure_gnutls_tls_crypto_policy

References:

disa	CCI-001453
nist	AC-17(2)
os-srg	SRG-OS-000250-GPOS-00093, SRG-OS-000423-GPOS-00187

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	true
Strategy:	restrict

- name: 'Configure GnuTLS library to use DoD-approved TLS Encryption: set_fact'
  set_fact:
    path: /etc/crypto-policies/back-ends/gnutls.config
    correct_value: +VERS-ALL:-VERS-DTLS0.9:-VERS-SSL3.0:-VERS-TLS1.0:-VERS-TLS1.1:-VERS-DTLS1.0
    lineinfile_reg: \+VERS-ALL:-VERS-DTLS0\.9:-VERS-SSL3\.0:-VERS-TLS1\.0:-VERS-TLS1\.1:-VERS-DTLS1\.0
  tags:
  - NIST-800-53-AC-17(2)
  - configure_gnutls_tls_crypto_policy
  - low_complexity
  - low_disruption
  - medium_severity
  - reboot_required
  - restrict_strategy

- name: 'Configure GnuTLS library to use DoD-approved TLS Encryption: stat'
  stat:
    path: '{{ path }}'
    follow: true
  register: gnutls_file
  tags:
  - NIST-800-53-AC-17(2)
  - configure_gnutls_tls_crypto_policy
  - low_complexity
  - low_disruption
  - medium_severity
  - reboot_required
  - restrict_strategy

- name: 'Configure GnuTLS library to use DoD-approved TLS Encryption: Add'
  lineinfile:
    path: '{{ path }}'
    regexp: '{{ lineinfile_reg }}'
    line: '{{ correct_value }}'
    create: true
  when: not gnutls_file.stat.exists or gnutls_file.stat.size <= correct_value|length
  tags:
  - NIST-800-53-AC-17(2)
  - configure_gnutls_tls_crypto_policy
  - low_complexity
  - low_disruption
  - medium_severity
  - reboot_required
  - restrict_strategy

- name: Configure GnuTLS library to use DoD-approved TLS Encryption
  block:

  - name: 'Configure GnuTLS library to use DoD-approved TLS Encryption: Existing value
      check'
    lineinfile:
      path: '{{ path }}'
      create: false
      regexp: '{{ lineinfile_reg }}'
      state: absent
    check_mode: true
    changed_when: false
    register: gnutls

  - name: 'Configure GnuTLS library to use DoD-approved TLS Encryption: Update'
    replace:
      path: '{{ path }}'
      regexp: (\+VERS-ALL(?::-VERS-[A-Z]+\d\.\d)+)
      replace: '{{ correct_value }}'
    when: gnutls.found is defined and gnutls.found != 1
  when: gnutls_file.stat.exists and gnutls_file.stat.size > correct_value|length
  tags:
  - NIST-800-53-AC-17(2)
  - configure_gnutls_tls_crypto_policy
  - low_complexity
  - low_disruption
  - medium_severity
  - reboot_required
  - restrict_strategy

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	true
Strategy:	restrict


CONF_FILE=/etc/crypto-policies/back-ends/gnutls.config
correct_value='+VERS-ALL:-VERS-DTLS0.9:-VERS-SSL3.0:-VERS-TLS1.0:-VERS-TLS1.1:-VERS-DTLS1.0'

grep -q ${correct_value} ${CONF_FILE}

if [[ $? -ne 0 ]]; then
    # We need to get the existing value, using PCRE to maintain same regex
    existing_value=$(grep -Po '(\+VERS-ALL(?::-VERS-[A-Z]+\d\.\d)+)' ${CONF_FILE})

    if [[ ! -z ${existing_value} ]]; then
        # replace existing_value with correct_value
        sed -i "s/${existing_value}/${correct_value}/g" ${CONF_FILE}
    else
        # ***NOTE*** #
        # This probably means this file is not here or it's been modified
        # unintentionally.
        # ********** #
        # echo correct_value to end
        echo ${correct_value} >> ${CONF_FILE}
    fi
fi

Rule Configure Kerberos to use System Crypto Policy [ref]

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.

Rationale:

Overriding the system crypto policy makes the behavior of Kerberos violate expectations, and makes system configuration more fragmented.

Severity:

high

Rule ID: xccdf_org.ssgproject.content_rule_configure_kerberos_crypto_policy

References:

disa	CCI-000803
ism	0418, 1055, 1402
nerc-cip	CIP-003-8 R4.2, CIP-007-3 R5.1
nist	SC-13, SC-12(2), SC-12(3)
os-srg	SRG-OS-000120-GPOS-00061

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	true
Strategy:	configure

- name: Configure Kerberos to use System Crypto Policy
  file:
    src: /etc/crypto-policies/back-ends/krb5.config
    path: /etc/krb5.conf.d/crypto-policies
    state: link
  tags:
  - NIST-800-53-SC-12(2)
  - NIST-800-53-SC-12(3)
  - NIST-800-53-SC-13
  - configure_kerberos_crypto_policy
  - configure_strategy
  - high_severity
  - low_complexity
  - low_disruption
  - reboot_required

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	true
Strategy:	configure


rm -f /etc/krb5.conf.d/crypto-policies
ln -s /etc/crypto-policies/back-ends/krb5.config /etc/krb5.conf.d/crypto-policies

Rule Configure Libreswan to use System Crypto Policy [ref]

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

Rationale:

Overriding the system crypto policy makes the behavior of the Libreswan service violate expectations, and makes system configuration more fragmented.

Severity:

high

Rule ID: xccdf_org.ssgproject.content_rule_configure_libreswan_crypto_policy

References:

disa	CCI-000068
nerc-cip	CIP-003-8 R4.2, CIP-007-3 R5.1
nist	CM-6(a), MA-4(6), SC-13, SC-12(2), SC-12(3)
pcidss	Req-2.2
os-srg	SRG-OS-000033-GPOS-00014

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Configure Libreswan to use System Crypto Policy
  lineinfile:
    path: /etc/ipsec.conf
    line: include /etc/crypto-policies/back-ends/libreswan.config
    create: true
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-MA-4(6)
  - NIST-800-53-SC-12(2)
  - NIST-800-53-SC-12(3)
  - NIST-800-53-SC-13
  - PCI-DSS-Req-2.2
  - configure_libreswan_crypto_policy
  - high_severity
  - low_complexity
  - low_disruption
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲


function remediate_libreswan_crypto_policy() {
    CONFIG_FILE="/etc/ipsec.conf"
    if ! grep -qP "^\s*include\s+/etc/crypto-policies/back-ends/libreswan.config\s*(?:#.*)?$" "$CONFIG_FILE" ; then
        # the file might not end with a new line
        echo -e '\ninclude /etc/crypto-policies/back-ends/libreswan.config' >> "$CONFIG_FILE"
    fi
    return 0
}

remediate_libreswan_crypto_policy

Rule Configure OpenSSL library to use System Crypto Policy [ref]

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.

Rationale:

Overriding the system crypto policy makes the behavior of the Java runtime violates expectations, and makes system configuration more fragmented.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_configure_openssl_crypto_policy

References:

disa	CCI-001453
nerc-cip	CIP-003-8 R4.2, CIP-007-3 R5.1, CIP-007-3 R7.1
nist	AC-17(a), AC-17(2), CM-6(a), MA-4(6), SC-13, SC-12(2), SC-12(3)
pcidss	Req-2.2
os-srg	SRG-OS-000250-GPOS-00093

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	false
Strategy:	unknown

- name: Configure OpenSSL library to use System Crypto Policy - Search for crypto_policy
    Section
  ansible.builtin.find:
    paths: /etc/pki/tls
    patterns: openssl.cnf
    contains: ^\s*\[\s*crypto_policy\s*]
  register: test_crypto_policy_group
  tags:
  - NIST-800-53-AC-17(2)
  - NIST-800-53-AC-17(a)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-MA-4(6)
  - NIST-800-53-SC-12(2)
  - NIST-800-53-SC-12(3)
  - NIST-800-53-SC-13
  - PCI-DSS-Req-2.2
  - configure_openssl_crypto_policy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - unknown_strategy

- name: Configure OpenSSL library to use System Crypto Policy - Search for crypto_policy
    Section Together With .include Directive
  ansible.builtin.find:
    paths: /etc/pki/tls
    patterns: openssl.cnf
    contains: ^\s*\.include\s*(?:=\s*)?/etc/crypto-policies/back-ends/opensslcnf.config$
  register: test_crypto_policy_include_directive
  tags:
  - NIST-800-53-AC-17(2)
  - NIST-800-53-AC-17(a)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-MA-4(6)
  - NIST-800-53-SC-12(2)
  - NIST-800-53-SC-12(3)
  - NIST-800-53-SC-13
  - PCI-DSS-Req-2.2
  - configure_openssl_crypto_policy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - unknown_strategy

- name: Configure OpenSSL library to use System Crypto Policy - Add .include Line
    for opensslcnf.config File in crypto_policy Section
  ansible.builtin.lineinfile:
    create: true
    insertafter: ^\s*\[\s*crypto_policy\s*]\s*
    line: .include = /etc/crypto-policies/back-ends/opensslcnf.config
    path: /etc/pki/tls/openssl.cnf
  when:
  - test_crypto_policy_group.matched > 0
  - test_crypto_policy_include_directive.matched == 0
  tags:
  - NIST-800-53-AC-17(2)
  - NIST-800-53-AC-17(a)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-MA-4(6)
  - NIST-800-53-SC-12(2)
  - NIST-800-53-SC-12(3)
  - NIST-800-53-SC-13
  - PCI-DSS-Req-2.2
  - configure_openssl_crypto_policy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - unknown_strategy

- name: Configure OpenSSL library to use System Crypto Policy - Add crypto_policy
    Section With .include for opensslcnf.config File
  ansible.builtin.lineinfile:
    create: true
    line: |-
      [crypto_policy]
      .include = /etc/crypto-policies/back-ends/opensslcnf.config
    path: /etc/pki/tls/openssl.cnf
  when: test_crypto_policy_group.matched == 0
  tags:
  - NIST-800-53-AC-17(2)
  - NIST-800-53-AC-17(a)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-MA-4(6)
  - NIST-800-53-SC-12(2)
  - NIST-800-53-SC-12(3)
  - NIST-800-53-SC-13
  - PCI-DSS-Req-2.2
  - configure_openssl_crypto_policy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - unknown_strategy

Remediation Shell script ⇲


OPENSSL_CRYPTO_POLICY_SECTION='[ crypto_policy ]'
OPENSSL_CRYPTO_POLICY_SECTION_REGEX='\[\s*crypto_policy\s*\]'

OPENSSL_CRYPTO_POLICY_INCLUSION='.include = /etc/crypto-policies/back-ends/opensslcnf.config'

OPENSSL_CRYPTO_POLICY_INCLUSION_REGEX='^\s*\.include\s*(?:=\s*)?/etc/crypto-policies/back-ends/opensslcnf.config$'



  


function remediate_openssl_crypto_policy() {
	CONFIG_FILE=/etc/pki/tls/openssl.cnf
	if test -f "$CONFIG_FILE"; then
		if ! grep -q "^\\s*$OPENSSL_CRYPTO_POLICY_SECTION_REGEX" "$CONFIG_FILE"; then
			printf '\n%s\n\n%s' "$OPENSSL_CRYPTO_POLICY_SECTION" "$OPENSSL_CRYPTO_POLICY_INCLUSION" >> "$CONFIG_FILE"
			return 0
		elif ! grep -q "^\\s*$OPENSSL_CRYPTO_POLICY_INCLUSION_REGEX" "$CONFIG_FILE"; then
			sed -i "s|$OPENSSL_CRYPTO_POLICY_SECTION_REGEX|&\\n\\n$OPENSSL_CRYPTO_POLICY_INCLUSION\\n|" "$CONFIG_FILE"
			return 0
		fi
	else
		echo "Aborting remediation as '$CONFIG_FILE' was not even found." >&2
		return 1
	fi
}

remediate_openssl_crypto_policy

Rule Configure SSH to use System Crypto Policy [ref]

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.

Rationale:

Overriding the system crypto policy makes the behavior of the SSH service violate expectations, and makes system configuration more fragmented.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_configure_ssh_crypto_policy

References:

disa	CCI-001453
hipaa	164.308(a)(4)(i), 164.308(b)(1), 164.308(b)(3), 164.312(e)(1), 164.312(e)(2)(ii)
nerc-cip	CIP-003-8 R4.2, CIP-007-3 R5.1, CIP-007-3 R7.1
nist	AC-17(a), AC-17(2), CM-6(a), MA-4(6), SC-13
ospp	FCS_SSH_EXT.1, FCS_SSHS_EXT.1, FCS_SSHC_EXT.1
pcidss	Req-2.2
os-srg	SRG-OS-000250-GPOS-00093
pcidss4	2.2.7, 2.2

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Configure SSH to use System Crypto Policy
  lineinfile:
    dest: /etc/sysconfig/sshd
    state: absent
    regexp: (?i)^\s*CRYPTO_POLICY.*$
  tags:
  - NIST-800-53-AC-17(2)
  - NIST-800-53-AC-17(a)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-MA-4(6)
  - NIST-800-53-SC-13
  - PCI-DSS-Req-2.2
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.7
  - configure_ssh_crypto_policy
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required

Remediation Shell script ⇲


SSH_CONF="/etc/sysconfig/sshd"

sed -i "/^\s*CRYPTO_POLICY.*$/Id" $SSH_CONF

Group GNOME Desktop Environment Group contains 1 group and 2 rules

[ref] GNOME is a graphical desktop environment bundled with many Linux distributions that allow users to easily interact with the operating system graphically rather than textually. The GNOME Graphical Display Manager (GDM) provides login, logout, and user switching contexts as well as display server management.

GNOME is developed by the GNOME Project and is considered the default Red Hat Graphical environment.

For more information on GNOME and the GNOME Project, see https://www.gnome.org.

Group Configure GNOME Login Screen Group contains 2 rules

[ref] In the default GNOME desktop, the login is displayed after system boot and can display user accounts, allow users to reboot the system, and allow users to login automatically and/or with a guest account. The login screen should be configured to prevent such behavior.

For more information about enforcing preferences in the GNOME3 environment using the DConf configuration system, see https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/desktop_migration_and_administration_guide/> and the man page dconf(1).

Rule Disable GDM Automatic Login [ref]

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

Rationale:

Failure to restrict system access to authenticated users negatively impacts operating system security.

Severity:

high

Rule ID: xccdf_org.ssgproject.content_rule_gnome_gdm_disable_automatic_login

References:

cis-csc	11, 3, 9
cobit5	BAI10.01, BAI10.02, BAI10.03, BAI10.05
cui	3.1.1
disa	CCI-000366
isa-62443-2009	4.3.4.3.2, 4.3.4.3.3
isa-62443-2013	SR 7.6
iso27001-2013	A.12.1.2, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4
nist	CM-6(a), AC-6(1), CM-7(b)
nist-csf	PR.IP-1
os-srg	SRG-OS-000480-GPOS-00229
pcidss4	8.3.1, 8.3

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	false
Strategy:	unknown

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.1.1
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(b)
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.1
  - gnome_gdm_disable_automatic_login
  - high_severity
  - low_complexity
  - medium_disruption
  - no_reboot_needed
  - unknown_strategy

- name: Disable GDM Automatic Login
  ini_file:
    dest: /etc/gdm/custom.conf
    section: daemon
    option: AutomaticLoginEnable
    value: 'false'
    no_extra_spaces: true
    create: true
  when:
  - '"gdm" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - NIST-800-171-3.1.1
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(b)
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.1
  - gnome_gdm_disable_automatic_login
  - high_severity
  - low_complexity
  - medium_disruption
  - no_reboot_needed
  - unknown_strategy

Remediation Shell script ⇲

# Remediation is applicable only in certain platforms
if rpm --quiet -q gdm && { [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; }; then

if rpm --quiet -q gdm
then
	if ! grep -q "^AutomaticLoginEnable=" /etc/gdm/custom.conf
	then
		sed -i "/^\[daemon\]/a \
		AutomaticLoginEnable=False" /etc/gdm/custom.conf
	else
		sed -i "s/^AutomaticLoginEnable=.*/AutomaticLoginEnable=False/g" /etc/gdm/custom.conf
	fi
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Disable XDMCP in GDM [ref]

XDMCP is an unencrypted protocol, and therefore, presents a security risk, see e.g. XDMCP Gnome docs. To disable XDMCP support in Gnome, set Enable to false under the [xdmcp] configuration section in /etc/gdm/custom.conf. For example:

[xdmcp]
Enable=false

Rationale:

XDMCP provides unencrypted remote access through the Gnome Display Manager (GDM) which does not provide for the confidentiality and integrity of user passwords or the remote session. If a privileged user were to login using XDMCP, the privileged user password could be compromised due to typed XEvents and keystrokes will traversing over the network in clear text.

Severity:

high

Rule ID: xccdf_org.ssgproject.content_rule_gnome_gdm_disable_xdmcp

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	false
Strategy:	unknown

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - gnome_gdm_disable_xdmcp
  - high_severity
  - low_complexity
  - medium_disruption
  - no_reboot_needed
  - unknown_strategy

- name: Disable XDMCP in GDM
  ini_file:
    path: /etc/gdm/custom.conf
    section: xdmcp
    option: Enable
    value: 'false'
    create: true
    mode: 420
  when: '"gdm" in ansible_facts.packages'
  tags:
  - gnome_gdm_disable_xdmcp
  - high_severity
  - low_complexity
  - medium_disruption
  - no_reboot_needed
  - unknown_strategy

Remediation Shell script ⇲

# Remediation is applicable only in certain platforms
if rpm --quiet -q gdm; then

# Try find '[xdmcp]' and 'Enable' in '/etc/gdm/custom.conf', if it exists, set
# to 'false', if it isn't here, add it, if '[xdmcp]' doesn't exist, add it there
if grep -qzosP '[[:space:]]*\[xdmcp]([^\n\[]*\n+)+?[[:space:]]*Enable' '/etc/gdm/custom.conf'; then
    
    sed -i "s/Enable[^(\n)]*/Enable=false/" '/etc/gdm/custom.conf'
elif grep -qs '[[:space:]]*\[xdmcp]' '/etc/gdm/custom.conf'; then
    sed -i "/[[:space:]]*\[xdmcp]/a Enable=false" '/etc/gdm/custom.conf'
else
    if test -d "/etc/gdm"; then
        printf '%s\n' '[xdmcp]' "Enable=false" >> '/etc/gdm/custom.conf'
    else
        echo "Config file directory '/etc/gdm' doesnt exist, not remediating, assuming non-applicability." >&2
    fi
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Group Sudo Group contains 6 rules

[ref] Sudo, which stands for "su 'do'", provides the ability to delegate authority to certain users, groups of users, or system administrators. When configured for system users and/or groups, Sudo can allow a user or group to execute privileged commands that normally only root is allowed to execute.

For more information on Sudo and addition Sudo configuration options, see https://www.sudo.ws.

Rule Install sudo Package [ref]

The sudo package can be installed with the following command:

$ sudo dnf install sudo

Rationale:

sudo is a program designed to allow a system administrator to give limited root privileges to users and log root activity. The basic philosophy is to give as few privileges as possible but still allow system users to get their work done.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_package_sudo_installed

References:

disa	CCI-002235
ism	1382, 1384, 1386
nist	CM-6(a)
ospp	FMT_MOF_EXT.1
os-srg	SRG-OS-000324-GPOS-00125
anssi	R33
pcidss4	2.2.6, 2.2

Remediation Puppet snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable

include install_sudo

class install_sudo {
  package { 'sudo':
    ensure => 'installed',
  }
}

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-53-CM-6(a)
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - enable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - package_sudo_installed

- name: Ensure sudo is installed
  package:
    name: sudo
    state: present
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-53-CM-6(a)
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - enable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - package_sudo_installed

Remediation script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable


package install sudo

Remediation OSBuild Blueprint snippet ⇲


[[packages]]
name = "sudo"
version = "*"

Remediation script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable


dnf install sudo

Remediation Anaconda snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable


package --add=sudo

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

if ! rpm -q --quiet "sudo" ; then
    dnf install -y "sudo"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Ensure Only Users Logged In To Real tty Can Execute Sudo - sudo use_pty [ref]

The sudo use_pty tag, when specified, will only execute sudo commands from users logged in to a real tty. This should be enabled by making sure that the use_pty tag exists in /etc/sudoers configuration file or any sudo configuration snippets in /etc/sudoers.d/.

Rationale:

Requiring that sudo commands be run in a pseudo-terminal can prevent an attacker from retaining access to the user's terminal after the main program has finished executing.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sudo_add_use_pty

References:

pcidss	Req-10.2.5
anssi	R39
pcidss4	2.2.6, 2.2

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - PCI-DSS-Req-10.2.5
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - sudo_add_use_pty

- name: Ensure use_pty is enabled in /etc/sudoers
  lineinfile:
    path: /etc/sudoers
    regexp: ^[\s]*Defaults.*\buse_pty\b.*$
    line: Defaults use_pty
    validate: /usr/sbin/visudo -cf %s
  when: '"sudo" in ansible_facts.packages'
  tags:
  - PCI-DSS-Req-10.2.5
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - sudo_add_use_pty

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

# Remediation is applicable only in certain platforms
if rpm --quiet -q sudo; then

if /usr/sbin/visudo -qcf /etc/sudoers; then
    cp /etc/sudoers /etc/sudoers.bak
    if ! grep -P '^[\s]*Defaults[\s]*\buse_pty\b.*$' /etc/sudoers; then
        # sudoers file doesn't define Option use_pty
        echo "Defaults use_pty" >> /etc/sudoers
    fi
    
    # Check validity of sudoers and cleanup bak
    if /usr/sbin/visudo -qcf /etc/sudoers; then
        rm -f /etc/sudoers.bak
    else
        echo "Fail to validate remediated /etc/sudoers, reverting to original file."
        mv /etc/sudoers.bak /etc/sudoers
        false
    fi
else
    echo "Skipping remediation, /etc/sudoers failed to validate"
    false
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Ensure Sudo Logfile Exists - sudo logfile [ref]

A custom log sudo file can be configured with the 'logfile' tag. This rule configures a sudo custom logfile at the default location suggested by CIS, which uses /var/log/sudo.log.

Rationale:

A sudo log file simplifies auditing of sudo commands.

Severity:

low

Rule ID: xccdf_org.ssgproject.content_rule_sudo_custom_logfile

References:

pcidss	Req-10.2.5
pcidss4	2.2.6, 2.2

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - PCI-DSS-Req-10.2.5
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - low_complexity
  - low_disruption
  - low_severity
  - no_reboot_needed
  - restrict_strategy
  - sudo_custom_logfile
- name: XCCDF Value var_sudo_logfile # promote to variable
  set_fact:
    var_sudo_logfile: !!str /var/log/sudo.log
  tags:
    - always

- name: Ensure logfile is enabled with the appropriate value in /etc/sudoers
  lineinfile:
    path: /etc/sudoers
    regexp: ^[\s]*Defaults\s(.*)\blogfile=[-]?.+\b(.*)$
    line: Defaults \1logfile={{ var_sudo_logfile }}\2
    validate: /usr/sbin/visudo -cf %s
    backrefs: true
  register: edit_sudoers_logfile_option
  when: '"sudo" in ansible_facts.packages'
  tags:
  - PCI-DSS-Req-10.2.5
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - low_complexity
  - low_disruption
  - low_severity
  - no_reboot_needed
  - restrict_strategy
  - sudo_custom_logfile

- name: Enable logfile option with appropriate value in /etc/sudoers
  lineinfile:
    path: /etc/sudoers
    line: Defaults logfile={{ var_sudo_logfile }}
    validate: /usr/sbin/visudo -cf %s
  when:
  - '"sudo" in ansible_facts.packages'
  - edit_sudoers_logfile_option is defined and not edit_sudoers_logfile_option.changed
  tags:
  - PCI-DSS-Req-10.2.5
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - low_complexity
  - low_disruption
  - low_severity
  - no_reboot_needed
  - restrict_strategy
  - sudo_custom_logfile

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

# Remediation is applicable only in certain platforms
if rpm --quiet -q sudo; then

var_sudo_logfile='/var/log/sudo.log'


if /usr/sbin/visudo -qcf /etc/sudoers; then
    cp /etc/sudoers /etc/sudoers.bak
    if ! grep -P '^[\s]*Defaults[\s]*\blogfile\s*=\s*(?:"?([^",\s]+)"?)\b.*$' /etc/sudoers; then
        # sudoers file doesn't define Option logfile
        echo "Defaults logfile=${var_sudo_logfile}" >> /etc/sudoers
    else
        # sudoers file defines Option logfile, remediate if appropriate value is not set
        if ! grep -P "^[\s]*Defaults.*\blogfile=${var_sudo_logfile}\b.*$" /etc/sudoers; then
            
            escaped_variable=${var_sudo_logfile//$'/'/$'\/'}
            sed -Ei "s/(^[\s]*Defaults.*\blogfile=)[-]?.+(\b.*$)/\1$escaped_variable\2/" /etc/sudoers
        fi
    fi
    
    # Check validity of sudoers and cleanup bak
    if /usr/sbin/visudo -qcf /etc/sudoers; then
        rm -f /etc/sudoers.bak
    else
        echo "Fail to validate remediated /etc/sudoers, reverting to original file."
        mv /etc/sudoers.bak /etc/sudoers
        false
    fi
else
    echo "Skipping remediation, /etc/sudoers failed to validate"
    false
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Ensure Users Re-Authenticate for Privilege Escalation - sudo [ref]

The sudo NOPASSWD and !authenticate option, when specified, allows a user to execute commands using sudo without having to authenticate. This should be disabled by making sure that NOPASSWD and/or !authenticate do not exist in /etc/sudoers configuration file or any sudo configuration snippets in /etc/sudoers.d/."

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sudo_require_authentication

References:

cis-csc	1, 12, 15, 16, 5
cobit5	DSS05.04, DSS05.10, DSS06.03, DSS06.10
disa	CCI-002038, CCI-004895
isa-62443-2009	4.3.3.5.1, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9
isa-62443-2013	SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9
iso27001-2013	A.18.1.4, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.2, A.9.4.3
nist	IA-11, CM-6(a)
nist-csf	PR.AC-1, PR.AC-7
os-srg	SRG-OS-000373-GPOS-00156
pcidss4	2.2.6, 2.2

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Find /etc/sudoers.d/ files
  ansible.builtin.find:
    paths:
    - /etc/sudoers.d/
  register: sudoers
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-11
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - sudo_require_authentication

- name: Remove lines containing NOPASSWD from sudoers files
  ansible.builtin.replace:
    regexp: (^(?!#).*[\s]+NOPASSWD[\s]*\:.*$)
    replace: '# \g<1>'
    path: '{{ item.path }}'
    validate: /usr/sbin/visudo -cf %s
  with_items:
  - path: /etc/sudoers
  - '{{ sudoers.files }}'
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-11
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - sudo_require_authentication

- name: Find /etc/sudoers.d/ files
  ansible.builtin.find:
    paths:
    - /etc/sudoers.d/
  register: sudoers
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-11
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - sudo_require_authentication

- name: Remove lines containing !authenticate from sudoers files
  ansible.builtin.replace:
    regexp: (^(?!#).*[\s]+\!authenticate.*$)
    replace: '# \g<1>'
    path: '{{ item.path }}'
    validate: /usr/sbin/visudo -cf %s
  with_items:
  - path: /etc/sudoers
  - '{{ sudoers.files }}'
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-11
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - sudo_require_authentication

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict


for f in /etc/sudoers /etc/sudoers.d/* ; do
  if [ ! -e "$f" ] ; then
    continue
  fi
  matching_list=$(grep -P '^(?!#).*[\s]+NOPASSWD[\s]*\:.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      # comment out "NOPASSWD" matches to preserve user data
      sed -i "s/^${entry}$/# &/g" $f
    done <<< "$matching_list"

    /usr/sbin/visudo -cf $f &> /dev/null || echo "Fail to validate $f with visudo"
  fi
done

for f in /etc/sudoers /etc/sudoers.d/* ; do
  if [ ! -e "$f" ] ; then
    continue
  fi
  matching_list=$(grep -P '^(?!#).*[\s]+\!authenticate.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      # comment out "!authenticate" matches to preserve user data
      sed -i "s/^${entry}$/# &/g" $f
    done <<< "$matching_list"

    /usr/sbin/visudo -cf $f &> /dev/null || echo "Fail to validate $f with visudo"
  fi
done

Rule Require Re-Authentication When Using the sudo Command [ref]

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.

Rationale:

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sudo_require_reauthentication

References:

disa	CCI-004895
nist	IA-11
os-srg	SRG-OS-000373-GPOS-00156, SRG-OS-000373-GPOS-00157, SRG-OS-000373-GPOS-00158
pcidss4	2.2.6, 2.2

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-53-IA-11
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - sudo_require_reauthentication
- name: XCCDF Value var_sudo_timestamp_timeout # promote to variable
  set_fact:
    var_sudo_timestamp_timeout: !!str 5
  tags:
    - always

- name: Require Re-Authentication When Using the sudo Command - Find /etc/sudoers.d/*
    files containing 'Defaults timestamp_timeout'
  ansible.builtin.find:
    path: /etc/sudoers.d
    patterns: '*'
    contains: ^[\s]*Defaults\s.*\btimestamp_timeout[\s]*=.*
  register: sudoers_d_defaults_timestamp_timeout
  when: '"sudo" in ansible_facts.packages'
  tags:
  - NIST-800-53-IA-11
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - sudo_require_reauthentication

- name: Require Re-Authentication When Using the sudo Command - Remove 'Defaults timestamp_timeout'
    from /etc/sudoers.d/* files
  ansible.builtin.lineinfile:
    path: '{{ item.path }}'
    regexp: ^[\s]*Defaults\s.*\btimestamp_timeout[\s]*=.*
    state: absent
  with_items: '{{ sudoers_d_defaults_timestamp_timeout.files }}'
  when: '"sudo" in ansible_facts.packages'
  tags:
  - NIST-800-53-IA-11
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - sudo_require_reauthentication

- name: Require Re-Authentication When Using the sudo Command - Ensure timestamp_timeout
    has the appropriate value in /etc/sudoers
  ansible.builtin.lineinfile:
    path: /etc/sudoers
    regexp: ^[\s]*Defaults\s(.*)\btimestamp_timeout[\s]*=[\s]*[-]?\w+\b(.*)$
    line: Defaults \1timestamp_timeout={{ var_sudo_timestamp_timeout }}\2
    validate: /usr/sbin/visudo -cf %s
    backrefs: true
  register: edit_sudoers_timestamp_timeout_option
  when: '"sudo" in ansible_facts.packages'
  tags:
  - NIST-800-53-IA-11
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - sudo_require_reauthentication

- name: Require Re-Authentication When Using the sudo Command - Enable timestamp_timeout
    option with correct value in /etc/sudoers
  ansible.builtin.lineinfile:
    path: /etc/sudoers
    line: Defaults timestamp_timeout={{ var_sudo_timestamp_timeout }}
    validate: /usr/sbin/visudo -cf %s
  when:
  - '"sudo" in ansible_facts.packages'
  - |
    edit_sudoers_timestamp_timeout_option is defined and not edit_sudoers_timestamp_timeout_option.changed
  tags:
  - NIST-800-53-IA-11
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - sudo_require_reauthentication

- name: Require Re-Authentication When Using the sudo Command - Remove timestamp_timeout
    wrong values in /etc/sudoers
  ansible.builtin.lineinfile:
    path: /etc/sudoers
    regexp: ^[\s]*Defaults\s.*\btimestamp_timeout[\s]*=[\s]*(?!{{ var_sudo_timestamp_timeout
      }}\b)[-]?\w+\b.*$
    state: absent
    validate: /usr/sbin/visudo -cf %s
  when: '"sudo" in ansible_facts.packages'
  tags:
  - NIST-800-53-IA-11
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - sudo_require_reauthentication

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

# Remediation is applicable only in certain platforms
if rpm --quiet -q sudo; then

var_sudo_timestamp_timeout='5'


if grep -Px '^[\s]*Defaults.*timestamp_timeout[\s]*=.*' /etc/sudoers.d/*; then
    find /etc/sudoers.d/ -type f -exec sed -Ei "/^[[:blank:]]*Defaults.*timestamp_timeout[[:blank:]]*=.*/d" {} \;
fi

if /usr/sbin/visudo -qcf /etc/sudoers; then
    cp /etc/sudoers /etc/sudoers.bak
    if ! grep -P '^[\s]*Defaults.*timestamp_timeout[\s]*=[\s]*[-]?\w+.*$' /etc/sudoers; then
        # sudoers file doesn't define Option timestamp_timeout
        echo "Defaults timestamp_timeout=${var_sudo_timestamp_timeout}" >> /etc/sudoers
    else
        # sudoers file defines Option timestamp_timeout, remediate wrong values if present
        if grep -qP "^[\s]*Defaults\s.*\btimestamp_timeout[\s]*=[\s]*(?!${var_sudo_timestamp_timeout}\b)[-]?\w+\b.*$" /etc/sudoers; then
            sed -Ei "s/(^[[:blank:]]*Defaults.*timestamp_timeout[[:blank:]]*=)[[:blank:]]*[-]?\w+(.*$)/\1${var_sudo_timestamp_timeout}\2/" /etc/sudoers
        fi
    fi
    
    # Check validity of sudoers and cleanup bak
    if /usr/sbin/visudo -qcf /etc/sudoers; then
        rm -f /etc/sudoers.bak
    else
        echo "Fail to validate remediated /etc/sudoers, reverting to original file."
        mv /etc/sudoers.bak /etc/sudoers
        false
    fi
else
    echo "Skipping remediation, /etc/sudoers failed to validate"
    false
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Ensure sudo only includes the default configuration directory [ref]

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.

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sudoers_default_includedir

References:

disa	CCI-000366
os-srg	SRG-OS-000480-GPOS-00227

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

- name: Check for duplicate values
  lineinfile:
    path: /etc/sudoers
    create: false
    regexp: ^#includedir.*$
    state: absent
  check_mode: true
  changed_when: false
  register: dupes
  tags:
  - configure_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - sudoers_default_includedir

- name: Deduplicate values from /etc/sudoers
  lineinfile:
    path: /etc/sudoers
    create: false
    regexp: ^#includedir.*$
    state: absent
  when: dupes.found is defined and dupes.found > 1
  tags:
  - configure_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - sudoers_default_includedir

- name: Insert correct line into /etc/sudoers
  lineinfile:
    path: /etc/sudoers
    create: false
    regexp: ^#includedir.*$
    line: '#includedir /etc/sudoers.d'
    state: present
  tags:
  - configure_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - sudoers_default_includedir

- name: Ensure sudoers doesn't include other non-default file
  lineinfile:
    path: /etc/sudoers
    create: false
    regexp: ^[#@]include[\s]+.*$
    state: absent
  tags:
  - configure_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - sudoers_default_includedir

- name: Ensure sudoers doesn't have non-default includedir
  lineinfile:
    path: /etc/sudoers
    create: false
    regexp: ^@includedir[\s]+.*$
    state: absent
  tags:
  - configure_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - sudoers_default_includedir

- name: Find out if /etc/sudoers.d/* files contain file or directory includes
  find:
    path: /etc/sudoers.d
    patterns: '*'
    contains: ^[#@]include(dir)?\s.*$
  register: sudoers_d_includes
  tags:
  - configure_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - sudoers_default_includedir

- name: Remove found occurrences of file and directory includes from /etc/sudoers.d/*
    files
  lineinfile:
    path: '{{ item.path }}'
    regexp: ^[#@]include(dir)?\s.*$
    state: absent
  with_items: '{{ sudoers_d_includes.files }}'
  tags:
  - configure_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - sudoers_default_includedir

Remediation Shell script ⇲


sudoers_config_file="/etc/sudoers"
sudoers_config_dir="/etc/sudoers.d"
sudoers_includedir_count=$(grep -c "#includedir" "$sudoers_config_file")
if [ "$sudoers_includedir_count" -gt 1 ]; then
    sed -i "/#includedir/d" "$sudoers_config_file"
    echo "#includedir /etc/sudoers.d" >> "$sudoers_config_file"
elif [ "$sudoers_includedir_count" -eq 0 ]; then
    echo "#includedir /etc/sudoers.d" >> "$sudoers_config_file"
else
    if ! grep -q "^#includedir /etc/sudoers.d" "$sudoers_config_file"; then
        sed -i "s|^#includedir.*|#includedir /etc/sudoers.d|g" "$sudoers_config_file"
    fi
fi

sed -Ei "/^#include\s/d; /^@includedir\s/d" "$sudoers_config_file"

if grep -Pr "^[#@]include(dir)?\s" "$sudoers_config_dir" ; then
    sed -Ei "/^[#@]include(dir)?\s/d" "$sudoers_config_dir"/*
fi

Group Updating Software Group contains 1 rule

[ref] The dnf command line tool is used to install and update software packages. The system also provides a graphical software update tool in the System menu, in the Administration submenu, called Software Update.

Fedora systems contain an installed software catalog called the RPM database, which records metadata of installed packages. Consistently using dnf or the graphical Software Update for all software installation allows for insight into the current inventory of installed software on the system.

Rule Install GNOME Software [ref]

The gnome-software package can be installed with the following command:

$ sudo dnf install gnome-software

Rationale:

The GNOME software package must be installed so that it can be used for software and firmware updates.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_package_gnome_software_installed

Remediation Puppet snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable

include install_gnome-software

class install_gnome-software {
  package { 'gnome-software':
    ensure => 'installed',
  }
}

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable

- name: Ensure gnome-software is installed
  package:
    name: gnome-software
    state: present
  tags:
  - enable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - package_gnome_software_installed

Remediation script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable


package install gnome-software

Remediation OSBuild Blueprint snippet ⇲


[[packages]]
name = "gnome-software"
version = "*"

Remediation script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable


dnf install gnome-software

Remediation Anaconda snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable


package --add=gnome-software

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable


if ! rpm -q --quiet "gnome-software" ; then
    dnf install -y "gnome-software"
fi

Group Account and Access Control Group contains 12 groups and 32 rules

[ref] In traditional Unix security, if an attacker gains shell access to a certain login account, they can perform any action or access any file to which that account has access. Therefore, making it more difficult for unauthorized people to gain shell access to accounts, particularly to privileged accounts, is a necessary part of securing a system. This section introduces mechanisms for restricting access to accounts under Fedora.

Group Protect Accounts by Configuring PAM Group contains 4 groups and 11 rules

[ref] PAM, or Pluggable Authentication Modules, is a system which implements modular authentication for Linux programs. PAM provides a flexible and configurable architecture for authentication, and it should be configured to minimize exposure to unnecessary risk. This section contains guidance on how to accomplish that.

PAM is implemented as a set of shared objects which are loaded and invoked whenever an application wishes to authenticate a user. Typically, the application must be running as root in order to take advantage of PAM, because PAM's modules often need to be able to access sensitive stores of account information, such as /etc/shadow. Traditional privileged network listeners (e.g. sshd) or SUID programs (e.g. sudo) already meet this requirement. An SUID root application, userhelper, is provided so that programs which are not SUID or privileged themselves can still take advantage of PAM.

PAM looks in the directory /etc/pam.d for application-specific configuration information. For instance, if the program login attempts to authenticate a user, then PAM's libraries follow the instructions in the file /etc/pam.d/login to determine what actions should be taken.

One very important file in /etc/pam.d is /etc/pam.d/system-auth. This file, which is included by many other PAM configuration files, defines 'default' system authentication measures. Modifying this file is a good way to make far-reaching authentication changes, for instance when implementing a centralized authentication service.

Warning: Be careful when making changes to PAM's configuration files. The syntax for these files is complex, and modifications can have unexpected consequences. The default configurations shipped with applications should be sufficient for most users.

Warning: Running authconfig or system-config-authentication will re-write the PAM configuration files, destroying any manually made changes and replacing them with a series of system defaults. One reference to the configuration file syntax can be found at https://fossies.org/linux/Linux-PAM-docs/doc/sag/Linux-PAM_SAG.pdf.

Group Set Lockouts for Failed Password Attempts Group contains 1 rule

[ref] The pam_faillock PAM module provides the capability to lock out user accounts after a number of failed login attempts. Its documentation is available in /usr/share/doc/pam-VERSION/txts/README.pam_faillock.

Warning: Locking out user accounts presents the risk of a denial-of-service attack. The lockout policy must weigh whether the risk of such a denial-of-service attack outweighs the benefits of thwarting password guessing attacks.

Rule An SELinux Context must be configured for the pam_faillock.so records directory [ref]

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.

Rationale:

Not having the correct SELinux context on the pam_faillock.so records directory may lead to unauthorized access to the directory.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_account_password_selinux_faillock_dir

References:

disa	CCI-000044
nist	AC-7 (a)
os-srg	SRG-OS-000021-GPOS-00005

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-53-AC-7 (a)
  - account_password_selinux_faillock_dir
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: An SELinux Context must be configured for the pam_faillock.so records directory
    - Get directories from faillock
  ansible.builtin.shell: grep -oP '^\s*(?:auth.*pam_faillock.so.*)?dir\s*=\s*(\S+)'
    "{{ item }}" | sed -r 's/.*=\s*(\S+)/\1/'
  register: faillock_output
  with_items:
  - /etc/security/faillock.conf
  - /etc/pam.d/system-auth
  - /etc/pam.d/password-auth
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-53-AC-7 (a)
  - account_password_selinux_faillock_dir
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: An SELinux Context must be configured for the pam_faillock.so records directory
    - Create a list directories from faillock
  ansible.builtin.set_fact:
    list_faillock_dir: '{{ faillock_output.results | map(attribute=''stdout_lines'')
      | flatten }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-53-AC-7 (a)
  - account_password_selinux_faillock_dir
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: An SELinux Context must be configured for the pam_faillock.so records directory
    - Create directories for faillock
  ansible.builtin.file:
    path: '{{ item }}'
    state: directory
  with_items: '{{ list_faillock_dir }}'
  when:
  - '"kernel" in ansible_facts.packages'
  - item != ""
  tags:
  - NIST-800-53-AC-7 (a)
  - account_password_selinux_faillock_dir
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: An SELinux Context must be configured for the pam_faillock.so records directory
    - Set up SELinux context for faillock
  ansible.builtin.shell: |-
    if ! semanage fcontext -a -t faillog_t "{{ item }}(/.*)?"; then
      semanage fcontext -m -t faillog_t "{{ item }}(/.*)?"
    fi
  with_items: '{{ list_faillock_dir }}'
  when:
  - '"kernel" in ansible_facts.packages'
  - item != ""
  tags:
  - NIST-800-53-AC-7 (a)
  - account_password_selinux_faillock_dir
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: An SELinux Context must be configured for the pam_faillock.so records directory
    - Restore SELinux context
  ansible.builtin.command: restorecon -R -v "{{ item }}"
  with_items: '{{ list_faillock_dir }}'
  when:
  - '"kernel" in ansible_facts.packages'
  - item != ""
  tags:
  - NIST-800-53-AC-7 (a)
  - account_password_selinux_faillock_dir
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: An SELinux Context must be configured for the pam_faillock.so records directory
    - Verify pam_faillock.so configuration
  ansible.builtin.debug:
    msg: |-
      "The pam_faillock.so dir option is not set in the system.
      If this is not expected, make sure pam_faillock.so is properly configured."
  when:
  - '"kernel" in ansible_facts.packages'
  - list_faillock_dir | length == 0
  tags:
  - NIST-800-53-AC-7 (a)
  - account_password_selinux_faillock_dir
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

FAILLOCK_CONF_FILES="/etc/security/faillock.conf /etc/pam.d/system-auth /etc/pam.d/password-auth"
faillock_dirs=$(grep -oP "^\s*(?:auth.*pam_faillock.so.*)?dir\s*=\s*(\S+)" $FAILLOCK_CONF_FILES \
               | sed -r 's/.*=\s*(\S+)/\1/')

if [ -n "$faillock_dirs" ]; then
    for dir in $faillock_dirs; do
        if ! semanage fcontext -a -t faillog_t "$dir(/.*)?"; then
            semanage fcontext -m -t faillog_t "$dir(/.*)?"
        fi
        if [ ! -e $dir ]; then
            mkdir -p $dir
        fi
        restorecon -R -v $dir
    done
else
echo "
The pam_faillock.so dir option is not set in the system.
If this is not expected, make sure pam_faillock.so is properly configured."
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Group Set Password Quality Requirements Group contains 1 group and 7 rules

[ref] The default pam_pwquality PAM module provides strength checking for passwords. It performs a number of checks, such as making sure passwords are not similar to dictionary words, are of at least a certain length, are not the previous password reversed, and are not simply a change of case from the previous password. It can also require passwords to be in certain character classes. The pam_pwquality module is the preferred way of configuring password requirements.

The man pages pam_pwquality(8) provide information on the capabilities and configuration of each.

Group Set Password Quality Requirements with pam_pwquality Group contains 7 rules

[ref] The pam_pwquality PAM module can be configured to meet requirements for a variety of policies.

For example, to configure pam_pwquality to require at least one uppercase character, lowercase character, digit, and other (special) character, make sure that pam_pwquality exists in /etc/pam.d/system-auth:

password    requisite     pam_pwquality.so try_first_pass local_users_only retry=3 authtok_type=

If no such line exists, add one as the first line of the password section in /etc/pam.d/system-auth. Next, modify the settings in /etc/security/pwquality.conf to match the following:

difok = 4
minlen = 14
dcredit = -1
ucredit = -1
lcredit = -1
ocredit = -1
maxrepeat = 3

The arguments can be modified to ensure compliance with your organization's security policy. Discussion of each parameter follows.

Rule Ensure PAM Enforces Password Requirements - Minimum Different Characters [ref]

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.

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_accounts_password_pam_difok

References:

cis-csc	1, 12, 15, 16, 5
cjis	5.6.2.1.1
cobit5	DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.03, DSS06.10
disa	CCI-004066
isa-62443-2009	4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.2, 4.3.3.7.4
isa-62443-2013	SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.1
iso27001-2013	A.18.1.4, A.7.1.1, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.2, A.9.4.3
nist	IA-5(c), IA-5(1)(b), CM-6(a), IA-5(4)
nist-csf	PR.AC-1, PR.AC-6, PR.AC-7
os-srg	SRG-OS-000072-GPOS-00040

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.6.2.1.1
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(b)
  - NIST-800-53-IA-5(4)
  - NIST-800-53-IA-5(c)
  - accounts_password_pam_difok
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
- name: XCCDF Value var_password_pam_difok # promote to variable
  set_fact:
    var_password_pam_difok: !!str 8
  tags:
    - always

- name: Ensure PAM Enforces Password Requirements - Minimum Different Characters -
    Ensure PAM variable difok is set accordingly
  ansible.builtin.lineinfile:
    create: true
    dest: /etc/security/pwquality.conf
    regexp: ^#?\s*difok
    line: difok = {{ var_password_pam_difok }}
  when: '"pam" in ansible_facts.packages'
  tags:
  - CJIS-5.6.2.1.1
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(b)
  - NIST-800-53-IA-5(4)
  - NIST-800-53-IA-5(c)
  - accounts_password_pam_difok
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

# Remediation is applicable only in certain platforms
if rpm --quiet -q pam; then

var_password_pam_difok='8'






# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^difok")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$var_password_pam_difok"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^difok\\>" "/etc/security/pwquality.conf"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^difok\\>.*/$escaped_formatted_output/gi" "/etc/security/pwquality.conf"
else
    if [[ -s "/etc/security/pwquality.conf" ]] && [[ -n "$(tail -c 1 -- "/etc/security/pwquality.conf" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "/etc/security/pwquality.conf"
    fi
    printf '%s\n' "$formatted_output" >> "/etc/security/pwquality.conf"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Set Password Maximum Consecutive Repeating Characters [ref]

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.

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_accounts_password_pam_maxrepeat

References:

cis-csc	1, 12, 15, 16, 5
cobit5	DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.03, DSS06.10
disa	CCI-004066
isa-62443-2009	4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.2, 4.3.3.7.4
isa-62443-2013	SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.1
iso27001-2013	A.18.1.4, A.7.1.1, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.2, A.9.4.3
nist	IA-5(c), CM-6(a), IA-5(4)
nist-csf	PR.AC-1, PR.AC-6, PR.AC-7
os-srg	SRG-OS-000072-GPOS-00040

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(4)
  - NIST-800-53-IA-5(c)
  - accounts_password_pam_maxrepeat
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
- name: XCCDF Value var_password_pam_maxrepeat # promote to variable
  set_fact:
    var_password_pam_maxrepeat: !!str 3
  tags:
    - always

- name: Set Password Maximum Consecutive Repeating Characters - Ensure PAM variable
    maxrepeat is set accordingly
  ansible.builtin.lineinfile:
    create: true
    dest: /etc/security/pwquality.conf
    regexp: ^#?\s*maxrepeat
    line: maxrepeat = {{ var_password_pam_maxrepeat }}
  when: '"pam" in ansible_facts.packages'
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(4)
  - NIST-800-53-IA-5(c)
  - accounts_password_pam_maxrepeat
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

# Remediation is applicable only in certain platforms
if rpm --quiet -q pam; then

var_password_pam_maxrepeat='3'






# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^maxrepeat")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$var_password_pam_maxrepeat"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^maxrepeat\\>" "/etc/security/pwquality.conf"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^maxrepeat\\>.*/$escaped_formatted_output/gi" "/etc/security/pwquality.conf"
else
    if [[ -s "/etc/security/pwquality.conf" ]] && [[ -n "$(tail -c 1 -- "/etc/security/pwquality.conf" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "/etc/security/pwquality.conf"
    fi
    printf '%s\n' "$formatted_output" >> "/etc/security/pwquality.conf"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Ensure PAM Enforces Password Requirements - Minimum Different Categories [ref]

The pam_pwquality module's minclass parameter controls requirements for usage of different character classes, or types, of character that must exist in a password before it is considered valid. For example, setting this value to three (3) requires that any password must have characters from at least three different categories in order to be approved. The default value is zero (0), meaning there are no required classes. There are four categories available:

* Upper-case characters
* Lower-case characters
* Digits
* Special characters (for example, punctuation)

Modify the minclass setting in /etc/security/pwquality.conf entry to require 3 differing categories of characters when changing passwords.

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_accounts_password_pam_minclass

References:

cis-csc	1, 12, 15, 16, 5
cobit5	DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.03, DSS06.10
disa	CCI-004066
isa-62443-2009	4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.2, 4.3.3.7.4
isa-62443-2013	SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.1
ism	0421, 0422, 0431, 0974, 1173, 1401, 1504, 1505, 1546, 1557, 1558, 1559, 1560, 1561
iso27001-2013	A.18.1.4, A.7.1.1, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.2, A.9.4.3
nist	IA-5(c), IA-5(1)(a), CM-6(a), IA-5(4)
nist-csf	PR.AC-1, PR.AC-6, PR.AC-7
os-srg	SRG-OS-000072-GPOS-00040
anssi	R68

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(a)
  - NIST-800-53-IA-5(4)
  - NIST-800-53-IA-5(c)
  - accounts_password_pam_minclass
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
- name: XCCDF Value var_password_pam_minclass # promote to variable
  set_fact:
    var_password_pam_minclass: !!str 3
  tags:
    - always

- name: Ensure PAM Enforces Password Requirements - Minimum Different Categories -
    Ensure PAM variable minclass is set accordingly
  ansible.builtin.lineinfile:
    create: true
    dest: /etc/security/pwquality.conf
    regexp: ^#?\s*minclass
    line: minclass = {{ var_password_pam_minclass }}
  when: '"pam" in ansible_facts.packages'
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(a)
  - NIST-800-53-IA-5(4)
  - NIST-800-53-IA-5(c)
  - accounts_password_pam_minclass
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

# Remediation is applicable only in certain platforms
if rpm --quiet -q pam; then

var_password_pam_minclass='3'






# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^minclass")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$var_password_pam_minclass"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^minclass\\>" "/etc/security/pwquality.conf"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^minclass\\>.*/$escaped_formatted_output/gi" "/etc/security/pwquality.conf"
else
    if [[ -s "/etc/security/pwquality.conf" ]] && [[ -n "$(tail -c 1 -- "/etc/security/pwquality.conf" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "/etc/security/pwquality.conf"
    fi
    printf '%s\n' "$formatted_output" >> "/etc/security/pwquality.conf"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Ensure PAM Enforces Password Requirements - Minimum Length [ref]

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.

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_accounts_password_pam_minlen

References:

cis-csc	1, 12, 15, 16, 5
cjis	5.6.2.1.1
cobit5	DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.03, DSS06.10
disa	CCI-004066
isa-62443-2009	4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.2, 4.3.3.7.4
isa-62443-2013	SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.1
ism	0421, 0422, 0431, 0974, 1173, 1401, 1504, 1505, 1546, 1557, 1558, 1559, 1560, 1561
iso27001-2013	A.18.1.4, A.7.1.1, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.2, A.9.4.3
nist	IA-5(c), IA-5(1)(a), CM-6(a), IA-5(4)
nist-csf	PR.AC-1, PR.AC-6, PR.AC-7
ospp	FMT_SMF_EXT.1
pcidss	Req-8.2.3
os-srg	SRG-OS-000078-GPOS-00046
anssi	R31, R68
pcidss4	8.3.6, 8.3

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.6.2.1.1
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(a)
  - NIST-800-53-IA-5(4)
  - NIST-800-53-IA-5(c)
  - PCI-DSS-Req-8.2.3
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.6
  - accounts_password_pam_minlen
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
- name: XCCDF Value var_password_pam_minlen # promote to variable
  set_fact:
    var_password_pam_minlen: !!str 15
  tags:
    - always

- name: Ensure PAM Enforces Password Requirements - Minimum Length - Ensure PAM variable
    minlen is set accordingly
  ansible.builtin.lineinfile:
    create: true
    dest: /etc/security/pwquality.conf
    regexp: ^#?\s*minlen
    line: minlen = {{ var_password_pam_minlen }}
  when: '"pam" in ansible_facts.packages'
  tags:
  - CJIS-5.6.2.1.1
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(a)
  - NIST-800-53-IA-5(4)
  - NIST-800-53-IA-5(c)
  - PCI-DSS-Req-8.2.3
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.6
  - accounts_password_pam_minlen
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

# Remediation is applicable only in certain platforms
if rpm --quiet -q pam; then

var_password_pam_minlen='15'






# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^minlen")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$var_password_pam_minlen"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^minlen\\>" "/etc/security/pwquality.conf"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^minlen\\>.*/$escaped_formatted_output/gi" "/etc/security/pwquality.conf"
else
    if [[ -s "/etc/security/pwquality.conf" ]] && [[ -n "$(tail -c 1 -- "/etc/security/pwquality.conf" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "/etc/security/pwquality.conf"
    fi
    printf '%s\n' "$formatted_output" >> "/etc/security/pwquality.conf"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Ensure PAM password complexity module is enabled in password-auth [ref]

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.

Rationale:

Enabling PAM password complexity permits to enforce strong passwords and consequently makes the system less prone to dictionary attacks.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_accounts_password_pam_pwquality_password_auth

References:

disa	CCI-004066
os-srg	SRG-OS-000069-GPOS-00037, SRG-OS-000070-GPOS-00038, SRG-OS-000480-GPOS-00227

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - accounts_password_pam_pwquality_password_auth
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure PAM password complexity module is enabled in password-auth - Check
    if /etc/pam.d/password-auth file is present
  ansible.builtin.stat:
    path: /etc/pam.d/password-auth
  register: result_pam_file_present
  when: '"pam" in ansible_facts.packages'
  tags:
  - accounts_password_pam_pwquality_password_auth
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure PAM password complexity module is enabled in password-auth - Check
    the proper remediation for the system
  block:

  - name: Ensure PAM password complexity module is enabled in password-auth - Define
      the PAM file to be edited as a local fact
    ansible.builtin.set_fact:
      pam_file_path: /etc/pam.d/password-auth

  - name: Ensure PAM password complexity module is enabled in password-auth - Check
      if system relies on authselect tool
    ansible.builtin.stat:
      path: /usr/bin/authselect
    register: result_authselect_present

  - name: Ensure PAM password complexity module is enabled in password-auth - Ensure
      authselect custom profile is used if authselect is present
    block:

    - name: Ensure PAM password complexity module is enabled in password-auth - Check
        integrity of authselect current profile
      ansible.builtin.command:
        cmd: authselect check
      register: result_authselect_check_cmd
      changed_when: false
      failed_when: false

    - name: Ensure PAM password complexity module is enabled in password-auth - Informative
        message based on the authselect integrity check result
      ansible.builtin.assert:
        that:
        - result_authselect_check_cmd.rc == 0
        fail_msg:
        - authselect integrity check failed. Remediation aborted!
        - This remediation could not be applied because an authselect profile was
          not selected or the selected profile is not intact.
        - It is not recommended to manually edit the PAM files when authselect tool
          is available.
        - In cases where the default authselect profile does not cover a specific
          demand, a custom authselect profile is recommended.
        success_msg:
        - authselect integrity check passed

    - name: Ensure PAM password complexity module is enabled in password-auth - Get
        authselect current profile
      ansible.builtin.shell:
        cmd: authselect current -r | awk '{ print $1 }'
      register: result_authselect_profile
      changed_when: false
      when:
      - result_authselect_check_cmd is success

    - name: Ensure PAM password complexity module is enabled in password-auth - Define
        the current authselect profile as a local fact
      ansible.builtin.set_fact:
        authselect_current_profile: '{{ result_authselect_profile.stdout }}'
        authselect_custom_profile: '{{ result_authselect_profile.stdout }}'
      when:
      - result_authselect_profile is not skipped
      - result_authselect_profile.stdout is match("custom/")

    - name: Ensure PAM password complexity module is enabled in password-auth - Define
        the new authselect custom profile as a local fact
      ansible.builtin.set_fact:
        authselect_current_profile: '{{ result_authselect_profile.stdout }}'
        authselect_custom_profile: custom/hardening
      when:
      - result_authselect_profile is not skipped
      - result_authselect_profile.stdout is not match("custom/")

    - name: Ensure PAM password complexity module is enabled in password-auth - Get
        authselect current features to also enable them in the custom profile
      ansible.builtin.shell:
        cmd: authselect current | tail -n+3 | awk '{ print $2 }'
      register: result_authselect_features
      changed_when: false
      when:
      - result_authselect_profile is not skipped
      - authselect_current_profile is not match("custom/")

    - name: Ensure PAM password complexity module is enabled in password-auth - Check
        if any custom profile with the same name was already created
      ansible.builtin.stat:
        path: /etc/authselect/{{ authselect_custom_profile }}
      register: result_authselect_custom_profile_present
      changed_when: false
      when:
      - authselect_current_profile is not match("custom/")

    - name: Ensure PAM password complexity module is enabled in password-auth - Create
        an authselect custom profile based on the current profile
      ansible.builtin.command:
        cmd: authselect create-profile hardening -b {{ authselect_current_profile
          }}
      when:
      - result_authselect_check_cmd is success
      - authselect_current_profile is not match("custom/")
      - not result_authselect_custom_profile_present.stat.exists

    - name: Ensure PAM password complexity module is enabled in password-auth - Ensure
        authselect changes are applied
      ansible.builtin.command:
        cmd: authselect apply-changes -b --backup=before-hardening-custom-profile
      when:
      - result_authselect_check_cmd is success
      - result_authselect_profile is not skipped
      - authselect_current_profile is not match("custom/")
      - authselect_custom_profile is not match(authselect_current_profile)

    - name: Ensure PAM password complexity module is enabled in password-auth - Ensure
        the authselect custom profile is selected
      ansible.builtin.command:
        cmd: authselect select {{ authselect_custom_profile }}
      register: result_pam_authselect_select_profile
      when:
      - result_authselect_check_cmd is success
      - result_authselect_profile is not skipped
      - authselect_current_profile is not match("custom/")
      - authselect_custom_profile is not match(authselect_current_profile)

    - name: Ensure PAM password complexity module is enabled in password-auth - Restore
        the authselect features in the custom profile
      ansible.builtin.command:
        cmd: authselect enable-feature {{ item }}
      loop: '{{ result_authselect_features.stdout_lines }}'
      register: result_pam_authselect_restore_features
      when:
      - result_authselect_profile is not skipped
      - result_authselect_features is not skipped
      - result_pam_authselect_select_profile is not skipped

    - name: Ensure PAM password complexity module is enabled in password-auth - Ensure
        authselect changes are applied
      ansible.builtin.command:
        cmd: authselect apply-changes -b --backup=after-hardening-custom-profile
      when:
      - result_authselect_check_cmd is success
      - result_authselect_profile is not skipped
      - result_pam_authselect_restore_features is not skipped

    - name: Ensure PAM password complexity module is enabled in password-auth - Change
        the PAM file to be edited according to the custom authselect profile
      ansible.builtin.set_fact:
        pam_file_path: /etc/authselect/{{ authselect_custom_profile }}/{{ pam_file_path
          | basename }}
    when:
    - result_authselect_present.stat.exists

  - name: Ensure PAM password complexity module is enabled in password-auth - Define
      a fact for control already filtered in case filters are used
    ansible.builtin.set_fact:
      pam_module_control: requisite

  - name: Ensure PAM password complexity module is enabled in password-auth - Check
      if expected PAM module line is present in {{ pam_file_path }}
    ansible.builtin.lineinfile:
      path: '{{ pam_file_path }}'
      regexp: ^\s*password\s+{{ pam_module_control | regex_escape() }}\s+pam_pwquality.so\s*.*
      state: absent
    check_mode: true
    changed_when: false
    register: result_pam_line_present

  - name: Ensure PAM password complexity module is enabled in password-auth - Include
      or update the PAM module line in {{ pam_file_path }}
    block:

    - name: Ensure PAM password complexity module is enabled in password-auth - Check
        if required PAM module line is present in {{ pam_file_path }} with different
        control
      ansible.builtin.lineinfile:
        path: '{{ pam_file_path }}'
        regexp: ^\s*password\s+.*\s+pam_pwquality.so\s*
        state: absent
      check_mode: true
      changed_when: false
      register: result_pam_line_other_control_present

    - name: Ensure PAM password complexity module is enabled in password-auth - Ensure
        the correct control for the required PAM module line in {{ pam_file_path }}
      ansible.builtin.replace:
        dest: '{{ pam_file_path }}'
        regexp: ^(\s*password\s+).*(\bpam_pwquality.so.*)
        replace: \1{{ pam_module_control }} \2
      register: result_pam_module_edit
      when:
      - result_pam_line_other_control_present.found == 1

    - name: Ensure PAM password complexity module is enabled in password-auth - Ensure
        the required PAM module line is included in {{ pam_file_path }}
      ansible.builtin.lineinfile:
        dest: '{{ pam_file_path }}'
        insertafter: ^account.*required.*pam_permit\.so
        line: password    {{ pam_module_control }}    pam_pwquality.so
      register: result_pam_module_add
      when:
      - result_pam_line_other_control_present.found == 0 or result_pam_line_other_control_present.found
        > 1

    - name: Ensure PAM password complexity module is enabled in password-auth - Ensure
        authselect changes are applied
      ansible.builtin.command:
        cmd: authselect apply-changes -b
      when:
      - result_authselect_present is defined
      - result_authselect_present.stat.exists
      - |-
        (result_pam_module_add is defined and result_pam_module_add.changed)
         or (result_pam_module_edit is defined and result_pam_module_edit.changed)
    when:
    - result_pam_line_present.found is defined
    - result_pam_line_present.found == 0

  - name: Ensure PAM password complexity module is enabled in password-auth - Ensure
      authselect changes are applied
    ansible.builtin.command:
      cmd: authselect apply-changes -b
    when:
    - result_authselect_present.stat.exists
    - |-
      (result_pam_accounts_password_pam_pwquality_password_auth_add is defined and result_pam_accounts_password_pam_pwquality_password_auth_add.changed)
       or (result_pam_accounts_password_pam_pwquality_password_auth_edit is defined and result_pam_accounts_password_pam_pwquality_password_auth_edit.changed)
  when:
  - '"pam" in ansible_facts.packages'
  - result_pam_file_present.stat.exists
  tags:
  - accounts_password_pam_pwquality_password_auth
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed

Remediation Shell script ⇲

# Remediation is applicable only in certain platforms
if rpm --quiet -q pam; then

if [ -e "/etc/pam.d/password-auth" ] ; then
    PAM_FILE_PATH="/etc/pam.d/password-auth"
    if [ -f /usr/bin/authselect ]; then
        
        if ! authselect check; then
        echo "
        authselect integrity check failed. Remediation aborted!
        This remediation could not be applied because an authselect profile was not selected or the selected profile is not intact.
        It is not recommended to manually edit the PAM files when authselect tool is available.
        In cases where the default authselect profile does not cover a specific demand, a custom authselect profile is recommended."
        exit 1
        fi

        CURRENT_PROFILE=$(authselect current -r | awk '{ print $1 }')
        # If not already in use, a custom profile is created preserving the enabled features.
        if [[ ! $CURRENT_PROFILE == custom/* ]]; then
            ENABLED_FEATURES=$(authselect current | tail -n+3 | awk '{ print $2 }')
            authselect create-profile hardening -b $CURRENT_PROFILE
            CURRENT_PROFILE="custom/hardening"
            
            authselect apply-changes -b --backup=before-hardening-custom-profile
            authselect select $CURRENT_PROFILE
            for feature in $ENABLED_FEATURES; do
                authselect enable-feature $feature;
            done
            
            authselect apply-changes -b --backup=after-hardening-custom-profile
        fi
        PAM_FILE_NAME=$(basename "/etc/pam.d/password-auth")
        PAM_FILE_PATH="/etc/authselect/$CURRENT_PROFILE/$PAM_FILE_NAME"

        authselect apply-changes -b
    fi
    
if ! grep -qP "^\s*password\s+requisite\s+pam_pwquality.so\s*.*" "$PAM_FILE_PATH"; then
    # Line matching group + control + module was not found. Check group + module.
    if [ "$(grep -cP '^\s*password\s+.*\s+pam_pwquality.so\s*' "$PAM_FILE_PATH")" -eq 1 ]; then
        # The control is updated only if one single line matches.
        sed -i -E --follow-symlinks "s/^(\s*password\s+).*(\bpam_pwquality.so.*)/\1requisite \2/" "$PAM_FILE_PATH"
    else
        LAST_MATCH_LINE=$(grep -nP "^account.*required.*pam_permit\.so" "$PAM_FILE_PATH" | tail -n 1 | cut -d: -f 1)
        if [ ! -z $LAST_MATCH_LINE ]; then
            sed -i --follow-symlinks $LAST_MATCH_LINE" a password     requisite    pam_pwquality.so" "$PAM_FILE_PATH"
        else
            echo "password    requisite    pam_pwquality.so" >> "$PAM_FILE_PATH"
        fi
    fi
fi
    if [ -f /usr/bin/authselect ]; then
        
        authselect apply-changes -b
    fi
else
    echo "/etc/pam.d/password-auth was not found" >&2
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Ensure PAM password complexity module is enabled in system-auth [ref]

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.

Rationale:

Enabling PAM password complexity permits to enforce strong passwords and consequently makes the system less prone to dictionary attacks.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_accounts_password_pam_pwquality_system_auth

References:

disa	CCI-000366
os-srg	SRG-OS-000480-GPOS-00227

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - accounts_password_pam_pwquality_system_auth
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure PAM password complexity module is enabled in system-auth - Check if
    /etc/pam.d/system-auth file is present
  ansible.builtin.stat:
    path: /etc/pam.d/system-auth
  register: result_pam_file_present
  when: '"pam" in ansible_facts.packages'
  tags:
  - accounts_password_pam_pwquality_system_auth
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure PAM password complexity module is enabled in system-auth - Check the
    proper remediation for the system
  block:

  - name: Ensure PAM password complexity module is enabled in system-auth - Define
      the PAM file to be edited as a local fact
    ansible.builtin.set_fact:
      pam_file_path: /etc/pam.d/system-auth

  - name: Ensure PAM password complexity module is enabled in system-auth - Check
      if system relies on authselect tool
    ansible.builtin.stat:
      path: /usr/bin/authselect
    register: result_authselect_present

  - name: Ensure PAM password complexity module is enabled in system-auth - Ensure
      authselect custom profile is used if authselect is present
    block:

    - name: Ensure PAM password complexity module is enabled in system-auth - Check
        integrity of authselect current profile
      ansible.builtin.command:
        cmd: authselect check
      register: result_authselect_check_cmd
      changed_when: false
      failed_when: false

    - name: Ensure PAM password complexity module is enabled in system-auth - Informative
        message based on the authselect integrity check result
      ansible.builtin.assert:
        that:
        - result_authselect_check_cmd.rc == 0
        fail_msg:
        - authselect integrity check failed. Remediation aborted!
        - This remediation could not be applied because an authselect profile was
          not selected or the selected profile is not intact.
        - It is not recommended to manually edit the PAM files when authselect tool
          is available.
        - In cases where the default authselect profile does not cover a specific
          demand, a custom authselect profile is recommended.
        success_msg:
        - authselect integrity check passed

    - name: Ensure PAM password complexity module is enabled in system-auth - Get
        authselect current profile
      ansible.builtin.shell:
        cmd: authselect current -r | awk '{ print $1 }'
      register: result_authselect_profile
      changed_when: false
      when:
      - result_authselect_check_cmd is success

    - name: Ensure PAM password complexity module is enabled in system-auth - Define
        the current authselect profile as a local fact
      ansible.builtin.set_fact:
        authselect_current_profile: '{{ result_authselect_profile.stdout }}'
        authselect_custom_profile: '{{ result_authselect_profile.stdout }}'
      when:
      - result_authselect_profile is not skipped
      - result_authselect_profile.stdout is match("custom/")

    - name: Ensure PAM password complexity module is enabled in system-auth - Define
        the new authselect custom profile as a local fact
      ansible.builtin.set_fact:
        authselect_current_profile: '{{ result_authselect_profile.stdout }}'
        authselect_custom_profile: custom/hardening
      when:
      - result_authselect_profile is not skipped
      - result_authselect_profile.stdout is not match("custom/")

    - name: Ensure PAM password complexity module is enabled in system-auth - Get
        authselect current features to also enable them in the custom profile
      ansible.builtin.shell:
        cmd: authselect current | tail -n+3 | awk '{ print $2 }'
      register: result_authselect_features
      changed_when: false
      when:
      - result_authselect_profile is not skipped
      - authselect_current_profile is not match("custom/")

    - name: Ensure PAM password complexity module is enabled in system-auth - Check
        if any custom profile with the same name was already created
      ansible.builtin.stat:
        path: /etc/authselect/{{ authselect_custom_profile }}
      register: result_authselect_custom_profile_present
      changed_when: false
      when:
      - authselect_current_profile is not match("custom/")

    - name: Ensure PAM password complexity module is enabled in system-auth - Create
        an authselect custom profile based on the current profile
      ansible.builtin.command:
        cmd: authselect create-profile hardening -b {{ authselect_current_profile
          }}
      when:
      - result_authselect_check_cmd is success
      - authselect_current_profile is not match("custom/")
      - not result_authselect_custom_profile_present.stat.exists

    - name: Ensure PAM password complexity module is enabled in system-auth - Ensure
        authselect changes are applied
      ansible.builtin.command:
        cmd: authselect apply-changes -b --backup=before-hardening-custom-profile
      when:
      - result_authselect_check_cmd is success
      - result_authselect_profile is not skipped
      - authselect_current_profile is not match("custom/")
      - authselect_custom_profile is not match(authselect_current_profile)

    - name: Ensure PAM password complexity module is enabled in system-auth - Ensure
        the authselect custom profile is selected
      ansible.builtin.command:
        cmd: authselect select {{ authselect_custom_profile }}
      register: result_pam_authselect_select_profile
      when:
      - result_authselect_check_cmd is success
      - result_authselect_profile is not skipped
      - authselect_current_profile is not match("custom/")
      - authselect_custom_profile is not match(authselect_current_profile)

    - name: Ensure PAM password complexity module is enabled in system-auth - Restore
        the authselect features in the custom profile
      ansible.builtin.command:
        cmd: authselect enable-feature {{ item }}
      loop: '{{ result_authselect_features.stdout_lines }}'
      register: result_pam_authselect_restore_features
      when:
      - result_authselect_profile is not skipped
      - result_authselect_features is not skipped
      - result_pam_authselect_select_profile is not skipped

    - name: Ensure PAM password complexity module is enabled in system-auth - Ensure
        authselect changes are applied
      ansible.builtin.command:
        cmd: authselect apply-changes -b --backup=after-hardening-custom-profile
      when:
      - result_authselect_check_cmd is success
      - result_authselect_profile is not skipped
      - result_pam_authselect_restore_features is not skipped

    - name: Ensure PAM password complexity module is enabled in system-auth - Change
        the PAM file to be edited according to the custom authselect profile
      ansible.builtin.set_fact:
        pam_file_path: /etc/authselect/{{ authselect_custom_profile }}/{{ pam_file_path
          | basename }}
    when:
    - result_authselect_present.stat.exists

  - name: Ensure PAM password complexity module is enabled in system-auth - Define
      a fact for control already filtered in case filters are used
    ansible.builtin.set_fact:
      pam_module_control: requisite

  - name: Ensure PAM password complexity module is enabled in system-auth - Check
      if expected PAM module line is present in {{ pam_file_path }}
    ansible.builtin.lineinfile:
      path: '{{ pam_file_path }}'
      regexp: ^\s*password\s+{{ pam_module_control | regex_escape() }}\s+pam_pwquality.so\s*.*
      state: absent
    check_mode: true
    changed_when: false
    register: result_pam_line_present

  - name: Ensure PAM password complexity module is enabled in system-auth - Include
      or update the PAM module line in {{ pam_file_path }}
    block:

    - name: Ensure PAM password complexity module is enabled in system-auth - Check
        if required PAM module line is present in {{ pam_file_path }} with different
        control
      ansible.builtin.lineinfile:
        path: '{{ pam_file_path }}'
        regexp: ^\s*password\s+.*\s+pam_pwquality.so\s*
        state: absent
      check_mode: true
      changed_when: false
      register: result_pam_line_other_control_present

    - name: Ensure PAM password complexity module is enabled in system-auth - Ensure
        the correct control for the required PAM module line in {{ pam_file_path }}
      ansible.builtin.replace:
        dest: '{{ pam_file_path }}'
        regexp: ^(\s*password\s+).*(\bpam_pwquality.so.*)
        replace: \1{{ pam_module_control }} \2
      register: result_pam_module_edit
      when:
      - result_pam_line_other_control_present.found == 1

    - name: Ensure PAM password complexity module is enabled in system-auth - Ensure
        the required PAM module line is included in {{ pam_file_path }}
      ansible.builtin.lineinfile:
        dest: '{{ pam_file_path }}'
        insertafter: ^account.*required.*pam_permit\.so
        line: password    {{ pam_module_control }}    pam_pwquality.so
      register: result_pam_module_add
      when:
      - result_pam_line_other_control_present.found == 0 or result_pam_line_other_control_present.found
        > 1

    - name: Ensure PAM password complexity module is enabled in system-auth - Ensure
        authselect changes are applied
      ansible.builtin.command:
        cmd: authselect apply-changes -b
      when:
      - result_authselect_present is defined
      - result_authselect_present.stat.exists
      - |-
        (result_pam_module_add is defined and result_pam_module_add.changed)
         or (result_pam_module_edit is defined and result_pam_module_edit.changed)
    when:
    - result_pam_line_present.found is defined
    - result_pam_line_present.found == 0

  - name: Ensure PAM password complexity module is enabled in system-auth - Ensure
      authselect changes are applied
    ansible.builtin.command:
      cmd: authselect apply-changes -b
    when:
    - result_authselect_present.stat.exists
    - |-
      (result_pam_accounts_password_pam_pwquality_system_auth_add is defined and result_pam_accounts_password_pam_pwquality_system_auth_add.changed)
       or (result_pam_accounts_password_pam_pwquality_system_auth_edit is defined and result_pam_accounts_password_pam_pwquality_system_auth_edit.changed)
  when:
  - '"pam" in ansible_facts.packages'
  - result_pam_file_present.stat.exists
  tags:
  - accounts_password_pam_pwquality_system_auth
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed

Remediation Shell script ⇲

# Remediation is applicable only in certain platforms
if rpm --quiet -q pam; then

if [ -e "/etc/pam.d/system-auth" ] ; then
    PAM_FILE_PATH="/etc/pam.d/system-auth"
    if [ -f /usr/bin/authselect ]; then
        
        if ! authselect check; then
        echo "
        authselect integrity check failed. Remediation aborted!
        This remediation could not be applied because an authselect profile was not selected or the selected profile is not intact.
        It is not recommended to manually edit the PAM files when authselect tool is available.
        In cases where the default authselect profile does not cover a specific demand, a custom authselect profile is recommended."
        exit 1
        fi

        CURRENT_PROFILE=$(authselect current -r | awk '{ print $1 }')
        # If not already in use, a custom profile is created preserving the enabled features.
        if [[ ! $CURRENT_PROFILE == custom/* ]]; then
            ENABLED_FEATURES=$(authselect current | tail -n+3 | awk '{ print $2 }')
            authselect create-profile hardening -b $CURRENT_PROFILE
            CURRENT_PROFILE="custom/hardening"
            
            authselect apply-changes -b --backup=before-hardening-custom-profile
            authselect select $CURRENT_PROFILE
            for feature in $ENABLED_FEATURES; do
                authselect enable-feature $feature;
            done
            
            authselect apply-changes -b --backup=after-hardening-custom-profile
        fi
        PAM_FILE_NAME=$(basename "/etc/pam.d/system-auth")
        PAM_FILE_PATH="/etc/authselect/$CURRENT_PROFILE/$PAM_FILE_NAME"

        authselect apply-changes -b
    fi
    
if ! grep -qP "^\s*password\s+requisite\s+pam_pwquality.so\s*.*" "$PAM_FILE_PATH"; then
    # Line matching group + control + module was not found. Check group + module.
    if [ "$(grep -cP '^\s*password\s+.*\s+pam_pwquality.so\s*' "$PAM_FILE_PATH")" -eq 1 ]; then
        # The control is updated only if one single line matches.
        sed -i -E --follow-symlinks "s/^(\s*password\s+).*(\bpam_pwquality.so.*)/\1requisite \2/" "$PAM_FILE_PATH"
    else
        LAST_MATCH_LINE=$(grep -nP "^account.*required.*pam_permit\.so" "$PAM_FILE_PATH" | tail -n 1 | cut -d: -f 1)
        if [ ! -z $LAST_MATCH_LINE ]; then
            sed -i --follow-symlinks $LAST_MATCH_LINE" a password     requisite    pam_pwquality.so" "$PAM_FILE_PATH"
        else
            echo "password    requisite    pam_pwquality.so" >> "$PAM_FILE_PATH"
        fi
    fi
fi
    if [ -f /usr/bin/authselect ]; then
        
        authselect apply-changes -b
    fi
else
    echo "/etc/pam.d/system-auth was not found" >&2
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Ensure PAM Enforces Password Requirements - Authentication Retry Prompts Permitted Per-Session [ref]

To configure the number of retry prompts that are permitted per-session: Edit the pam_pwquality.so statement in /etc/pam.d/system-auth to show

retry=3

, or a lower value if site policy is more restrictive. The DoD requirement is a maximum of 3 prompts per session.

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_accounts_password_pam_retry

References:

cis-csc	1, 11, 12, 15, 16, 3, 5, 9
cjis	5.5.3
cobit5	BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.03, DSS06.10
disa	CCI-004066
isa-62443-2009	4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.2, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3
isa-62443-2013	SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 7.6
iso27001-2013	A.12.1.2, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4, A.18.1.4, A.7.1.1, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.2, A.9.4.3
nist	CM-6(a), AC-7(a), IA-5(4)
nist-csf	PR.AC-1, PR.AC-6, PR.AC-7, PR.IP-1
os-srg	SRG-OS-000069-GPOS-00037, SRG-OS-000480-GPOS-00227
anssi	R68

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.5.3
  - NIST-800-53-AC-7(a)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(4)
  - accounts_password_pam_retry
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
- name: XCCDF Value var_password_pam_retry # promote to variable
  set_fact:
    var_password_pam_retry: !!str 3
  tags:
    - always

- name: Ensure PAM Enforces Password Requirements - Authentication Retry Prompts Permitted
    Per-Session - Define a fact for control already filtered in case filters are used
  ansible.builtin.set_fact:
    pam_module_control: requisite
  when: '"pam" in ansible_facts.packages'
  tags:
  - CJIS-5.5.3
  - NIST-800-53-AC-7(a)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(4)
  - accounts_password_pam_retry
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure PAM Enforces Password Requirements - Authentication Retry Prompts Permitted
    Per-Session - Check if expected PAM module line is present in /etc/pam.d/system-auth
  ansible.builtin.lineinfile:
    path: /etc/pam.d/system-auth
    regexp: ^\s*password\s+{{ pam_module_control | regex_escape() }}\s+pam_pwquality.so\s*.*
    state: absent
  check_mode: true
  changed_when: false
  register: result_pam_line_present
  when: '"pam" in ansible_facts.packages'
  tags:
  - CJIS-5.5.3
  - NIST-800-53-AC-7(a)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(4)
  - accounts_password_pam_retry
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure PAM Enforces Password Requirements - Authentication Retry Prompts Permitted
    Per-Session - Include or update the PAM module line in /etc/pam.d/system-auth
  block:

  - name: Ensure PAM Enforces Password Requirements - Authentication Retry Prompts
      Permitted Per-Session - Check if required PAM module line is present in /etc/pam.d/system-auth
      with different control
    ansible.builtin.lineinfile:
      path: /etc/pam.d/system-auth
      regexp: ^\s*password\s+.*\s+pam_pwquality.so\s*
      state: absent
    check_mode: true
    changed_when: false
    register: result_pam_line_other_control_present

  - name: Ensure PAM Enforces Password Requirements - Authentication Retry Prompts
      Permitted Per-Session - Ensure the correct control for the required PAM module
      line in /etc/pam.d/system-auth
    ansible.builtin.replace:
      dest: /etc/pam.d/system-auth
      regexp: ^(\s*password\s+).*(\bpam_pwquality.so.*)
      replace: \1{{ pam_module_control }} \2
    register: result_pam_module_edit
    when:
    - result_pam_line_other_control_present.found == 1

  - name: Ensure PAM Enforces Password Requirements - Authentication Retry Prompts
      Permitted Per-Session - Ensure the required PAM module line is included in /etc/pam.d/system-auth
    ansible.builtin.lineinfile:
      dest: /etc/pam.d/system-auth
      insertafter: ^\s*account
      line: password    {{ pam_module_control }}    pam_pwquality.so
    register: result_pam_module_add
    when:
    - result_pam_line_other_control_present.found == 0 or result_pam_line_other_control_present.found
      > 1

  - name: Ensure PAM Enforces Password Requirements - Authentication Retry Prompts
      Permitted Per-Session - Ensure authselect changes are applied
    ansible.builtin.command:
      cmd: authselect apply-changes -b
    when:
    - result_authselect_present is defined
    - result_authselect_present.stat.exists
    - |-
      (result_pam_module_add is defined and result_pam_module_add.changed)
       or (result_pam_module_edit is defined and result_pam_module_edit.changed)
  when:
  - '"pam" in ansible_facts.packages'
  - result_pam_line_present.found is defined
  - result_pam_line_present.found == 0
  tags:
  - CJIS-5.5.3
  - NIST-800-53-AC-7(a)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(4)
  - accounts_password_pam_retry
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure PAM Enforces Password Requirements - Authentication Retry Prompts Permitted
    Per-Session - Define a fact for control already filtered in case filters are used
  ansible.builtin.set_fact:
    pam_module_control: requisite
  when: '"pam" in ansible_facts.packages'
  tags:
  - CJIS-5.5.3
  - NIST-800-53-AC-7(a)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(4)
  - accounts_password_pam_retry
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure PAM Enforces Password Requirements - Authentication Retry Prompts Permitted
    Per-Session - Check if the required PAM module option is present in /etc/pam.d/system-auth
  ansible.builtin.lineinfile:
    path: /etc/pam.d/system-auth
    regexp: ^\s*password\s+{{ pam_module_control | regex_escape() }}\s+pam_pwquality.so\s*.*\sretry\b
    state: absent
  check_mode: true
  changed_when: false
  register: result_pam_module_accounts_password_pam_retry_option_present
  when: '"pam" in ansible_facts.packages'
  tags:
  - CJIS-5.5.3
  - NIST-800-53-AC-7(a)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(4)
  - accounts_password_pam_retry
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure PAM Enforces Password Requirements - Authentication Retry Prompts Permitted
    Per-Session - Ensure the "retry" PAM option for "pam_pwquality.so" is included
    in /etc/pam.d/system-auth
  ansible.builtin.lineinfile:
    path: /etc/pam.d/system-auth
    backrefs: true
    regexp: ^(\s*password\s+{{ pam_module_control | regex_escape() }}\s+pam_pwquality.so.*)
    line: \1 retry={{ var_password_pam_retry }}
    state: present
  register: result_pam_accounts_password_pam_retry_add
  when:
  - '"pam" in ansible_facts.packages'
  - result_pam_module_accounts_password_pam_retry_option_present.found == 0
  tags:
  - CJIS-5.5.3
  - NIST-800-53-AC-7(a)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(4)
  - accounts_password_pam_retry
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure PAM Enforces Password Requirements - Authentication Retry Prompts Permitted
    Per-Session - Ensure the required value for "retry" PAM option from "pam_pwquality.so"
    in /etc/pam.d/system-auth
  ansible.builtin.lineinfile:
    path: /etc/pam.d/system-auth
    backrefs: true
    regexp: ^(\s*password\s+{{ pam_module_control | regex_escape() }}\s+pam_pwquality.so\s+.*)(retry)=[0-9a-zA-Z]+\s*(.*)
    line: \1\2={{ var_password_pam_retry }} \3
  register: result_pam_accounts_password_pam_retry_edit
  when:
  - '"pam" in ansible_facts.packages'
  - result_pam_module_accounts_password_pam_retry_option_present.found > 0
  tags:
  - CJIS-5.5.3
  - NIST-800-53-AC-7(a)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(4)
  - accounts_password_pam_retry
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed

Remediation Shell script ⇲

# Remediation is applicable only in certain platforms
if rpm --quiet -q pam; then

var_password_pam_retry='3'



	
		if [ -e "/etc/pam.d/system-auth" ] ; then
    PAM_FILE_PATH="/etc/pam.d/system-auth"
    if [ -f /usr/bin/authselect ]; then
        
        if ! authselect check; then
        echo "
        authselect integrity check failed. Remediation aborted!
        This remediation could not be applied because an authselect profile was not selected or the selected profile is not intact.
        It is not recommended to manually edit the PAM files when authselect tool is available.
        In cases where the default authselect profile does not cover a specific demand, a custom authselect profile is recommended."
        exit 1
        fi

        CURRENT_PROFILE=$(authselect current -r | awk '{ print $1 }')
        # If not already in use, a custom profile is created preserving the enabled features.
        if [[ ! $CURRENT_PROFILE == custom/* ]]; then
            ENABLED_FEATURES=$(authselect current | tail -n+3 | awk '{ print $2 }')
            authselect create-profile hardening -b $CURRENT_PROFILE
            CURRENT_PROFILE="custom/hardening"
            
            authselect apply-changes -b --backup=before-hardening-custom-profile
            authselect select $CURRENT_PROFILE
            for feature in $ENABLED_FEATURES; do
                authselect enable-feature $feature;
            done
            
            authselect apply-changes -b --backup=after-hardening-custom-profile
        fi
        PAM_FILE_NAME=$(basename "/etc/pam.d/system-auth")
        PAM_FILE_PATH="/etc/authselect/$CURRENT_PROFILE/$PAM_FILE_NAME"

        authselect apply-changes -b
    fi
    

        if ! grep -qP "^\s*password\s+requisite\s+pam_pwquality.so\s*.*" "$PAM_FILE_PATH"; then
            # Line matching group + control + module was not found. Check group + module.
            if [ "$(grep -cP '^\s*password\s+.*\s+pam_pwquality.so\s*' "$PAM_FILE_PATH")" -eq 1 ]; then
                # The control is updated only if one single line matches.
                sed -i -E --follow-symlinks "s/^(\s*password\s+).*(\bpam_pwquality.so.*)/\1requisite \2/" "$PAM_FILE_PATH"
            else
                LAST_MATCH_LINE=$(grep -nP "^\s*account" "$PAM_FILE_PATH" | tail -n 1 | cut -d: -f 1)
                if [ ! -z $LAST_MATCH_LINE ]; then
                    sed -i --follow-symlinks $LAST_MATCH_LINE" a password     requisite    pam_pwquality.so" "$PAM_FILE_PATH"
                else
                    echo "password    requisite    pam_pwquality.so" >> "$PAM_FILE_PATH"
                fi
            fi
        fi
        # Check the option
        if ! grep -qP "^\s*password\s+requisite\s+pam_pwquality.so\s*.*\sretry\b" "$PAM_FILE_PATH"; then
            sed -i -E --follow-symlinks "/\s*password\s+requisite\s+pam_pwquality.so.*/ s/$/ retry=$var_password_pam_retry/" "$PAM_FILE_PATH"
        else
            sed -i -E --follow-symlinks "s/(\s*password\s+requisite\s+pam_pwquality.so\s+.*)(retry=)[[:alnum:]]+\s*(.*)/\1\2$var_password_pam_retry \3/" "$PAM_FILE_PATH"
        fi
    if [ -f /usr/bin/authselect ]; then
        
        authselect apply-changes -b
    fi
else
    echo "/etc/pam.d/system-auth was not found" >&2
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Group Set Password Hashing Algorithm Group contains 3 rules

[ref] The system's default algorithm for storing password hashes in /etc/shadow is SHA-512. This can be configured in several locations.

Rule Set Password Hashing Algorithm in /etc/login.defs [ref]

In /etc/login.defs, add or update the following line to ensure the system will use SHA512 as the hashing algorithm:

ENCRYPT_METHOD SHA512

Rationale:

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_set_password_hashing_algorithm_logindefs

References:

cis-csc	1, 12, 15, 16, 5
cjis	5.6.2.2
cobit5	DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.03, DSS06.10
cui	3.13.11
disa	CCI-004062
isa-62443-2009	4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.2, 4.3.3.7.4
isa-62443-2013	SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.1
ism	0418, 1055, 1402
iso27001-2013	A.18.1.4, A.7.1.1, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.2, A.9.4.3
nist	IA-5(c), IA-5(1)(c), CM-6(a)
nist-csf	PR.AC-1, PR.AC-6, PR.AC-7
pcidss	Req-8.2.1
os-srg	SRG-OS-000073-GPOS-00041
pcidss4	8.3.2, 8.3

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.6.2.2
  - NIST-800-171-3.13.11
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(c)
  - NIST-800-53-IA-5(c)
  - PCI-DSS-Req-8.2.1
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.2
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - set_password_hashing_algorithm_logindefs
- name: XCCDF Value var_password_hashing_algorithm # promote to variable
  set_fact:
    var_password_hashing_algorithm: !!str SHA512
  tags:
    - always

- name: Set Password Hashing Algorithm in /etc/login.defs
  lineinfile:
    dest: /etc/login.defs
    regexp: ^#?ENCRYPT_METHOD
    line: ENCRYPT_METHOD {{ var_password_hashing_algorithm }}
    state: present
    create: true
  when: '"shadow-utils" in ansible_facts.packages'
  tags:
  - CJIS-5.6.2.2
  - NIST-800-171-3.13.11
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(c)
  - NIST-800-53-IA-5(c)
  - PCI-DSS-Req-8.2.1
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.2
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - set_password_hashing_algorithm_logindefs

Remediation Shell script ⇲

# Remediation is applicable only in certain platforms
if rpm --quiet -q shadow-utils; then

var_password_hashing_algorithm='SHA512'

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^ENCRYPT_METHOD")

# shellcheck disable=SC2059
printf -v formatted_output "%s %s" "$stripped_key" "$var_password_hashing_algorithm"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^ENCRYPT_METHOD\\>" "/etc/login.defs"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^ENCRYPT_METHOD\\>.*/$escaped_formatted_output/gi" "/etc/login.defs"
else
    if [[ -s "/etc/login.defs" ]] && [[ -n "$(tail -c 1 -- "/etc/login.defs" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "/etc/login.defs"
    fi
    printf '%s\n' "$formatted_output" >> "/etc/login.defs"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Set PAM''s Password Hashing Algorithm - password-auth [ref]

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.

Warning: The hashing algorithms to be used with pam_unix.so are defined with independent module options. There are at least 7 possible algorithms and likely more algorithms will be introduced along the time. Due the the number of options and its possible combinations, the use of multiple hashing algorithm options may bring unexpected behaviors to the system. For this reason the check will pass only when one hashing algorithm option is defined and is aligned to the "var_password_hashing_algorithm_pam" variable. The remediation will ensure the correct option and remove any other extra hashing algorithm option.

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_set_password_hashing_algorithm_passwordauth

References:

cis-csc	1, 12, 15, 16, 5
cjis	5.6.2.2
cobit5	DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.03, DSS06.10
cui	3.13.11
disa	CCI-004062
isa-62443-2009	4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.2, 4.3.3.7.4
isa-62443-2013	SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.1
ism	0418, 1055, 1402
iso27001-2013	A.18.1.4, A.7.1.1, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.2, A.9.4.3
nist	IA-5(c), IA-5(1)(c), CM-6(a)
nist-csf	PR.AC-1, PR.AC-6, PR.AC-7
pcidss	Req-8.2.1
os-srg	SRG-OS-000073-GPOS-00041, SRG-OS-000120-GPOS-00061

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.6.2.2
  - NIST-800-171-3.13.11
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(c)
  - NIST-800-53-IA-5(c)
  - PCI-DSS-Req-8.2.1
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - set_password_hashing_algorithm_passwordauth
- name: XCCDF Value var_password_hashing_algorithm_pam # promote to variable
  set_fact:
    var_password_hashing_algorithm_pam: !!str sha512
  tags:
    - always

- name: Set PAM's Password Hashing Algorithm - password-auth - Check if /etc/pam.d/password-auth
    file is present
  ansible.builtin.stat:
    path: /etc/pam.d/password-auth
  register: result_pam_file_present
  when: '"pam" in ansible_facts.packages'
  tags:
  - CJIS-5.6.2.2
  - NIST-800-171-3.13.11
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(c)
  - NIST-800-53-IA-5(c)
  - PCI-DSS-Req-8.2.1
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - set_password_hashing_algorithm_passwordauth

- name: Set PAM's Password Hashing Algorithm - password-auth - Check the proper remediation
    for the system
  block:

  - name: Set PAM's Password Hashing Algorithm - password-auth - Define the PAM file
      to be edited as a local fact
    ansible.builtin.set_fact:
      pam_file_path: /etc/pam.d/password-auth

  - name: Set PAM's Password Hashing Algorithm - password-auth - Check if system relies
      on authselect tool
    ansible.builtin.stat:
      path: /usr/bin/authselect
    register: result_authselect_present

  - name: Set PAM's Password Hashing Algorithm - password-auth - Ensure authselect
      custom profile is used if authselect is present
    block:

    - name: Set PAM's Password Hashing Algorithm - password-auth - Check integrity
        of authselect current profile
      ansible.builtin.command:
        cmd: authselect check
      register: result_authselect_check_cmd
      changed_when: false
      failed_when: false

    - name: Set PAM's Password Hashing Algorithm - password-auth - Informative message
        based on the authselect integrity check result
      ansible.builtin.assert:
        that:
        - result_authselect_check_cmd.rc == 0
        fail_msg:
        - authselect integrity check failed. Remediation aborted!
        - This remediation could not be applied because an authselect profile was
          not selected or the selected profile is not intact.
        - It is not recommended to manually edit the PAM files when authselect tool
          is available.
        - In cases where the default authselect profile does not cover a specific
          demand, a custom authselect profile is recommended.
        success_msg:
        - authselect integrity check passed

    - name: Set PAM's Password Hashing Algorithm - password-auth - Get authselect
        current profile
      ansible.builtin.shell:
        cmd: authselect current -r | awk '{ print $1 }'
      register: result_authselect_profile
      changed_when: false
      when:
      - result_authselect_check_cmd is success

    - name: Set PAM's Password Hashing Algorithm - password-auth - Define the current
        authselect profile as a local fact
      ansible.builtin.set_fact:
        authselect_current_profile: '{{ result_authselect_profile.stdout }}'
        authselect_custom_profile: '{{ result_authselect_profile.stdout }}'
      when:
      - result_authselect_profile is not skipped
      - result_authselect_profile.stdout is match("custom/")

    - name: Set PAM's Password Hashing Algorithm - password-auth - Define the new
        authselect custom profile as a local fact
      ansible.builtin.set_fact:
        authselect_current_profile: '{{ result_authselect_profile.stdout }}'
        authselect_custom_profile: custom/hardening
      when:
      - result_authselect_profile is not skipped
      - result_authselect_profile.stdout is not match("custom/")

    - name: Set PAM's Password Hashing Algorithm - password-auth - Get authselect
        current features to also enable them in the custom profile
      ansible.builtin.shell:
        cmd: authselect current | tail -n+3 | awk '{ print $2 }'
      register: result_authselect_features
      changed_when: false
      when:
      - result_authselect_profile is not skipped
      - authselect_current_profile is not match("custom/")

    - name: Set PAM's Password Hashing Algorithm - password-auth - Check if any custom
        profile with the same name was already created
      ansible.builtin.stat:
        path: /etc/authselect/{{ authselect_custom_profile }}
      register: result_authselect_custom_profile_present
      changed_when: false
      when:
      - authselect_current_profile is not match("custom/")

    - name: Set PAM's Password Hashing Algorithm - password-auth - Create an authselect
        custom profile based on the current profile
      ansible.builtin.command:
        cmd: authselect create-profile hardening -b {{ authselect_current_profile
          }}
      when:
      - result_authselect_check_cmd is success
      - authselect_current_profile is not match("custom/")
      - not result_authselect_custom_profile_present.stat.exists

    - name: Set PAM's Password Hashing Algorithm - password-auth - Ensure authselect
        changes are applied
      ansible.builtin.command:
        cmd: authselect apply-changes -b --backup=before-hardening-custom-profile
      when:
      - result_authselect_check_cmd is success
      - result_authselect_profile is not skipped
      - authselect_current_profile is not match("custom/")
      - authselect_custom_profile is not match(authselect_current_profile)

    - name: Set PAM's Password Hashing Algorithm - password-auth - Ensure the authselect
        custom profile is selected
      ansible.builtin.command:
        cmd: authselect select {{ authselect_custom_profile }}
      register: result_pam_authselect_select_profile
      when:
      - result_authselect_check_cmd is success
      - result_authselect_profile is not skipped
      - authselect_current_profile is not match("custom/")
      - authselect_custom_profile is not match(authselect_current_profile)

    - name: Set PAM's Password Hashing Algorithm - password-auth - Restore the authselect
        features in the custom profile
      ansible.builtin.command:
        cmd: authselect enable-feature {{ item }}
      loop: '{{ result_authselect_features.stdout_lines }}'
      register: result_pam_authselect_restore_features
      when:
      - result_authselect_profile is not skipped
      - result_authselect_features is not skipped
      - result_pam_authselect_select_profile is not skipped

    - name: Set PAM's Password Hashing Algorithm - password-auth - Ensure authselect
        changes are applied
      ansible.builtin.command:
        cmd: authselect apply-changes -b --backup=after-hardening-custom-profile
      when:
      - result_authselect_check_cmd is success
      - result_authselect_profile is not skipped
      - result_pam_authselect_restore_features is not skipped

    - name: Set PAM's Password Hashing Algorithm - password-auth - Change the PAM
        file to be edited according to the custom authselect profile
      ansible.builtin.set_fact:
        pam_file_path: /etc/authselect/{{ authselect_custom_profile }}/{{ pam_file_path
          | basename }}
    when:
    - result_authselect_present.stat.exists

  - name: Set PAM's Password Hashing Algorithm - password-auth - Define a fact for
      control already filtered in case filters are used
    ansible.builtin.set_fact:
      pam_module_control: sufficient

  - name: Set PAM's Password Hashing Algorithm - password-auth - Check if expected
      PAM module line is present in {{ pam_file_path }}
    ansible.builtin.lineinfile:
      path: '{{ pam_file_path }}'
      regexp: ^\s*password\s+{{ pam_module_control | regex_escape() }}\s+pam_unix.so\s*.*
      state: absent
    check_mode: true
    changed_when: false
    register: result_pam_line_present

  - name: Set PAM's Password Hashing Algorithm - password-auth - Include or update
      the PAM module line in {{ pam_file_path }}
    block:

    - name: Set PAM's Password Hashing Algorithm - password-auth - Check if required
        PAM module line is present in {{ pam_file_path }} with different control
      ansible.builtin.lineinfile:
        path: '{{ pam_file_path }}'
        regexp: ^\s*password\s+.*\s+pam_unix.so\s*
        state: absent
      check_mode: true
      changed_when: false
      register: result_pam_line_other_control_present

    - name: Set PAM's Password Hashing Algorithm - password-auth - Ensure the correct
        control for the required PAM module line in {{ pam_file_path }}
      ansible.builtin.replace:
        dest: '{{ pam_file_path }}'
        regexp: ^(\s*password\s+).*(\bpam_unix.so.*)
        replace: \1{{ pam_module_control }} \2
      register: result_pam_module_edit
      when:
      - result_pam_line_other_control_present.found == 1

    - name: Set PAM's Password Hashing Algorithm - password-auth - Ensure the required
        PAM module line is included in {{ pam_file_path }}
      ansible.builtin.lineinfile:
        dest: '{{ pam_file_path }}'
        line: password    {{ pam_module_control }}    pam_unix.so
      register: result_pam_module_add
      when:
      - result_pam_line_other_control_present.found == 0 or result_pam_line_other_control_present.found
        > 1

    - name: Set PAM's Password Hashing Algorithm - password-auth - Ensure authselect
        changes are applied
      ansible.builtin.command:
        cmd: authselect apply-changes -b
      when:
      - result_authselect_present is defined
      - result_authselect_present.stat.exists
      - |-
        (result_pam_module_add is defined and result_pam_module_add.changed)
         or (result_pam_module_edit is defined and result_pam_module_edit.changed)
    when:
    - result_pam_line_present.found is defined
    - result_pam_line_present.found == 0

  - name: Set PAM's Password Hashing Algorithm - password-auth - Define a fact for
      control already filtered in case filters are used
    ansible.builtin.set_fact:
      pam_module_control: sufficient

  - name: Set PAM's Password Hashing Algorithm - password-auth - Check if the required
      PAM module option is present in {{ pam_file_path }}
    ansible.builtin.lineinfile:
      path: '{{ pam_file_path }}'
      regexp: ^\s*password\s+{{ pam_module_control | regex_escape() }}\s+pam_unix.so\s*.*\s{{
        var_password_hashing_algorithm_pam }}\b
      state: absent
    check_mode: true
    changed_when: false
    register: result_pam_module_set_password_hashing_algorithm_passwordauth_option_present

  - name: Set PAM's Password Hashing Algorithm - password-auth - Ensure the "{{ var_password_hashing_algorithm_pam
      }}" PAM option for "pam_unix.so" is included in {{ pam_file_path }}
    ansible.builtin.lineinfile:
      path: '{{ pam_file_path }}'
      backrefs: true
      regexp: ^(\s*password\s+{{ pam_module_control | regex_escape() }}\s+pam_unix.so.*)
      line: \1 {{ var_password_hashing_algorithm_pam }}
      state: present
    register: result_pam_set_password_hashing_algorithm_passwordauth_add
    when:
    - result_pam_module_set_password_hashing_algorithm_passwordauth_option_present.found
      == 0

  - name: Set PAM's Password Hashing Algorithm - password-auth - Ensure authselect
      changes are applied
    ansible.builtin.command:
      cmd: authselect apply-changes -b
    when:
    - result_authselect_present.stat.exists
    - |-
      (result_pam_set_password_hashing_algorithm_passwordauth_add is defined and result_pam_set_password_hashing_algorithm_passwordauth_add.changed)
       or (result_pam_set_password_hashing_algorithm_passwordauth_edit is defined and result_pam_set_password_hashing_algorithm_passwordauth_edit.changed)
  when:
  - '"pam" in ansible_facts.packages'
  - result_pam_file_present.stat.exists
  tags:
  - CJIS-5.6.2.2
  - NIST-800-171-3.13.11
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(c)
  - NIST-800-53-IA-5(c)
  - PCI-DSS-Req-8.2.1
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - set_password_hashing_algorithm_passwordauth

- name: Set PAM's Password Hashing Algorithm - password-auth - Check if /etc/pam.d/password-auth
    File is Present
  ansible.builtin.stat:
    path: /etc/pam.d/password-auth
  register: result_pam_file_present
  when: '"pam" in ansible_facts.packages'
  tags:
  - CJIS-5.6.2.2
  - NIST-800-171-3.13.11
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(c)
  - NIST-800-53-IA-5(c)
  - PCI-DSS-Req-8.2.1
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - set_password_hashing_algorithm_passwordauth

- name: Set PAM's Password Hashing Algorithm - password-auth - Check The Proper Remediation
    For The System
  block:

  - name: Set PAM's Password Hashing Algorithm - password-auth - Define the PAM file
      to be edited as a local fact
    ansible.builtin.set_fact:
      pam_file_path: /etc/pam.d/password-auth

  - name: Set PAM's Password Hashing Algorithm - password-auth - Check if system relies
      on authselect tool
    ansible.builtin.stat:
      path: /usr/bin/authselect
    register: result_authselect_present

  - name: Set PAM's Password Hashing Algorithm - password-auth - Ensure authselect
      custom profile is used if authselect is present
    block:

    - name: Set PAM's Password Hashing Algorithm - password-auth - Check integrity
        of authselect current profile
      ansible.builtin.command:
        cmd: authselect check
      register: result_authselect_check_cmd
      changed_when: false
      failed_when: false

    - name: Set PAM's Password Hashing Algorithm - password-auth - Informative message
        based on the authselect integrity check result
      ansible.builtin.assert:
        that:
        - result_authselect_check_cmd.rc == 0
        fail_msg:
        - authselect integrity check failed. Remediation aborted!
        - This remediation could not be applied because an authselect profile was
          not selected or the selected profile is not intact.
        - It is not recommended to manually edit the PAM files when authselect tool
          is available.
        - In cases where the default authselect profile does not cover a specific
          demand, a custom authselect profile is recommended.
        success_msg:
        - authselect integrity check passed

    - name: Set PAM's Password Hashing Algorithm - password-auth - Get authselect
        current profile
      ansible.builtin.shell:
        cmd: authselect current -r | awk '{ print $1 }'
      register: result_authselect_profile
      changed_when: false
      when:
      - result_authselect_check_cmd is success

    - name: Set PAM's Password Hashing Algorithm - password-auth - Define the current
        authselect profile as a local fact
      ansible.builtin.set_fact:
        authselect_current_profile: '{{ result_authselect_profile.stdout }}'
        authselect_custom_profile: '{{ result_authselect_profile.stdout }}'
      when:
      - result_authselect_profile is not skipped
      - result_authselect_profile.stdout is match("custom/")

    - name: Set PAM's Password Hashing Algorithm - password-auth - Define the new
        authselect custom profile as a local fact
      ansible.builtin.set_fact:
        authselect_current_profile: '{{ result_authselect_profile.stdout }}'
        authselect_custom_profile: custom/hardening
      when:
      - result_authselect_profile is not skipped
      - result_authselect_profile.stdout is not match("custom/")

    - name: Set PAM's Password Hashing Algorithm - password-auth - Get authselect
        current features to also enable them in the custom profile
      ansible.builtin.shell:
        cmd: authselect current | tail -n+3 | awk '{ print $2 }'
      register: result_authselect_features
      changed_when: false
      when:
      - result_authselect_profile is not skipped
      - authselect_current_profile is not match("custom/")

    - name: Set PAM's Password Hashing Algorithm - password-auth - Check if any custom
        profile with the same name was already created
      ansible.builtin.stat:
        path: /etc/authselect/{{ authselect_custom_profile }}
      register: result_authselect_custom_profile_present
      changed_when: false
      when:
      - authselect_current_profile is not match("custom/")

    - name: Set PAM's Password Hashing Algorithm - password-auth - Create an authselect
        custom profile based on the current profile
      ansible.builtin.command:
        cmd: authselect create-profile hardening -b {{ authselect_current_profile
          }}
      when:
      - result_authselect_check_cmd is success
      - authselect_current_profile is not match("custom/")
      - not result_authselect_custom_profile_present.stat.exists

    - name: Set PAM's Password Hashing Algorithm - password-auth - Ensure authselect
        changes are applied
      ansible.builtin.command:
        cmd: authselect apply-changes -b --backup=before-hardening-custom-profile
      when:
      - result_authselect_check_cmd is success
      - result_authselect_profile is not skipped
      - authselect_current_profile is not match("custom/")
      - authselect_custom_profile is not match(authselect_current_profile)

    - name: Set PAM's Password Hashing Algorithm - password-auth - Ensure the authselect
        custom profile is selected
      ansible.builtin.command:
        cmd: authselect select {{ authselect_custom_profile }}
      register: result_pam_authselect_select_profile
      when:
      - result_authselect_check_cmd is success
      - result_authselect_profile is not skipped
      - authselect_current_profile is not match("custom/")
      - authselect_custom_profile is not match(authselect_current_profile)

    - name: Set PAM's Password Hashing Algorithm - password-auth - Restore the authselect
        features in the custom profile
      ansible.builtin.command:
        cmd: authselect enable-feature {{ item }}
      loop: '{{ result_authselect_features.stdout_lines }}'
      register: result_pam_authselect_restore_features
      when:
      - result_authselect_profile is not skipped
      - result_authselect_features is not skipped
      - result_pam_authselect_select_profile is not skipped

    - name: Set PAM's Password Hashing Algorithm - password-auth - Ensure authselect
        changes are applied
      ansible.builtin.command:
        cmd: authselect apply-changes -b --backup=after-hardening-custom-profile
      when:
      - result_authselect_check_cmd is success
      - result_authselect_profile is not skipped
      - result_pam_authselect_restore_features is not skipped

    - name: Set PAM's Password Hashing Algorithm - password-auth - Change the PAM
        file to be edited according to the custom authselect profile
      ansible.builtin.set_fact:
        pam_file_path: /etc/authselect/{{ authselect_custom_profile }}/{{ pam_file_path
          | basename }}
    when:
    - result_authselect_present.stat.exists

  - name: Set PAM's Password Hashing Algorithm - password-auth - Ensure That Only
      the Correct Hashing Algorithm Option For pam_unix.so Is Used in /etc/pam.d/password-auth
    ansible.builtin.replace:
      dest: '{{ pam_file_path }}'
      regexp: (^\s*password.*pam_unix\.so.*)\b{{ item }}\b\s*(.*)
      replace: \1\2
    when: item != var_password_hashing_algorithm_pam
    loop:
    - sha512
    - yescrypt
    - gost_yescrypt
    - blowfish
    - sha256
    - md5
    - bigcrypt
    register: result_pam_hashing_options_removal

  - name: Set PAM's Password Hashing Algorithm - password-auth - Ensure authselect
      changes are applied
    ansible.builtin.command:
      cmd: authselect apply-changes -b
    when:
    - result_authselect_present.stat.exists
    - result_pam_hashing_options_removal is changed
  when:
  - '"pam" in ansible_facts.packages'
  - result_pam_file_present.stat.exists
  tags:
  - CJIS-5.6.2.2
  - NIST-800-171-3.13.11
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(c)
  - NIST-800-53-IA-5(c)
  - PCI-DSS-Req-8.2.1
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - set_password_hashing_algorithm_passwordauth

Remediation Shell script ⇲

# Remediation is applicable only in certain platforms
if rpm --quiet -q pam; then

var_password_hashing_algorithm_pam='sha512'

PAM_FILE_PATH="/etc/pam.d/password-auth"

if [ -e "$PAM_FILE_PATH" ] ; then
    PAM_FILE_PATH="$PAM_FILE_PATH"
    if [ -f /usr/bin/authselect ]; then
        
        if ! authselect check; then
        echo "
        authselect integrity check failed. Remediation aborted!
        This remediation could not be applied because an authselect profile was not selected or the selected profile is not intact.
        It is not recommended to manually edit the PAM files when authselect tool is available.
        In cases where the default authselect profile does not cover a specific demand, a custom authselect profile is recommended."
        exit 1
        fi

        CURRENT_PROFILE=$(authselect current -r | awk '{ print $1 }')
        # If not already in use, a custom profile is created preserving the enabled features.
        if [[ ! $CURRENT_PROFILE == custom/* ]]; then
            ENABLED_FEATURES=$(authselect current | tail -n+3 | awk '{ print $2 }')
            authselect create-profile hardening -b $CURRENT_PROFILE
            CURRENT_PROFILE="custom/hardening"
            
            authselect apply-changes -b --backup=before-hardening-custom-profile
            authselect select $CURRENT_PROFILE
            for feature in $ENABLED_FEATURES; do
                authselect enable-feature $feature;
            done
            
            authselect apply-changes -b --backup=after-hardening-custom-profile
        fi
        PAM_FILE_NAME=$(basename "$PAM_FILE_PATH")
        PAM_FILE_PATH="/etc/authselect/$CURRENT_PROFILE/$PAM_FILE_NAME"

        authselect apply-changes -b
    fi
    

        if ! grep -qP "^\s*password\s+sufficient\s+pam_unix.so\s*.*" "$PAM_FILE_PATH"; then
            # Line matching group + control + module was not found. Check group + module.
            if [ "$(grep -cP '^\s*password\s+.*\s+pam_unix.so\s*' "$PAM_FILE_PATH")" -eq 1 ]; then
                # The control is updated only if one single line matches.
                sed -i -E --follow-symlinks "s/^(\s*password\s+).*(\bpam_unix.so.*)/\1sufficient \2/" "$PAM_FILE_PATH"
            else
                echo "password    sufficient    pam_unix.so" >> "$PAM_FILE_PATH"
            fi
        fi
        # Check the option
        if ! grep -qP "^\s*password\s+sufficient\s+pam_unix.so\s*.*\s$var_password_hashing_algorithm_pam\b" "$PAM_FILE_PATH"; then
            sed -i -E --follow-symlinks "/\s*password\s+sufficient\s+pam_unix.so.*/ s/$/ $var_password_hashing_algorithm_pam/" "$PAM_FILE_PATH"
        fi
    if [ -f /usr/bin/authselect ]; then
        
        authselect apply-changes -b
    fi
else
    echo "$PAM_FILE_PATH was not found" >&2
fi

# Ensure only the correct hashing algorithm option is used.
declare -a HASHING_ALGORITHMS_OPTIONS=("sha512" "yescrypt" "gost_yescrypt" "blowfish" "sha256" "md5" "bigcrypt")

for hash_option in "${HASHING_ALGORITHMS_OPTIONS[@]}"; do
  if [ "$hash_option" != "$var_password_hashing_algorithm_pam" ]; then
    if grep -qP "^\s*password\s+.*\s+pam_unix.so\s+.*\b$hash_option\b" "$PAM_FILE_PATH"; then
      if [ -e "$PAM_FILE_PATH" ] ; then
    PAM_FILE_PATH="$PAM_FILE_PATH"
    if [ -f /usr/bin/authselect ]; then
        
        if ! authselect check; then
        echo "
        authselect integrity check failed. Remediation aborted!
        This remediation could not be applied because an authselect profile was not selected or the selected profile is not intact.
        It is not recommended to manually edit the PAM files when authselect tool is available.
        In cases where the default authselect profile does not cover a specific demand, a custom authselect profile is recommended."
        exit 1
        fi

        CURRENT_PROFILE=$(authselect current -r | awk '{ print $1 }')
        # If not already in use, a custom profile is created preserving the enabled features.
        if [[ ! $CURRENT_PROFILE == custom/* ]]; then
            ENABLED_FEATURES=$(authselect current | tail -n+3 | awk '{ print $2 }')
            authselect create-profile hardening -b $CURRENT_PROFILE
            CURRENT_PROFILE="custom/hardening"
            
            authselect apply-changes -b --backup=before-hardening-custom-profile
            authselect select $CURRENT_PROFILE
            for feature in $ENABLED_FEATURES; do
                authselect enable-feature $feature;
            done
            
            authselect apply-changes -b --backup=after-hardening-custom-profile
        fi
        PAM_FILE_NAME=$(basename "$PAM_FILE_PATH")
        PAM_FILE_PATH="/etc/authselect/$CURRENT_PROFILE/$PAM_FILE_NAME"

        authselect apply-changes -b
    fi
    
if grep -qP "^\s*password\s+.*\s+pam_unix.so\s.*\b$hash_option\b" "$PAM_FILE_PATH"; then
    sed -i -E --follow-symlinks "s/(.*password.*.*.*pam_unix.so.*)\s$hash_option=?[[:alnum:]]*(.*)/\1\2/g" "$PAM_FILE_PATH"
fi
    if [ -f /usr/bin/authselect ]; then
        
        authselect apply-changes -b
    fi
else
    echo "$PAM_FILE_PATH was not found" >&2
fi
    fi
  fi
done

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Set PAM''s Password Hashing Algorithm [ref]

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.

Rationale:

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_set_password_hashing_algorithm_systemauth

References:

cis-csc	1, 12, 15, 16, 5
cjis	5.6.2.2
cobit5	DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.03, DSS06.10
cui	3.13.11
disa	CCI-000196, CCI-000803, CCI-004062
isa-62443-2009	4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.2, 4.3.3.7.4
isa-62443-2013	SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.1
ism	0418, 1055, 1402
iso27001-2013	A.18.1.4, A.7.1.1, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.2, A.9.4.3
nist	IA-5(c), IA-5(1)(c), CM-6(a)
nist-csf	PR.AC-1, PR.AC-6, PR.AC-7
pcidss	Req-8.2.1
os-srg	SRG-OS-000073-GPOS-00041, SRG-OS-000120-GPOS-00061
anssi	R68
pcidss4	8.3.2, 8.3

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.6.2.2
  - NIST-800-171-3.13.11
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(c)
  - NIST-800-53-IA-5(c)
  - PCI-DSS-Req-8.2.1
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.2
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - set_password_hashing_algorithm_systemauth
- name: XCCDF Value var_password_hashing_algorithm_pam # promote to variable
  set_fact:
    var_password_hashing_algorithm_pam: !!str sha512
  tags:
    - always

- name: Set PAM's Password Hashing Algorithm - Check if /etc/pam.d/system-auth file
    is present
  ansible.builtin.stat:
    path: /etc/pam.d/system-auth
  register: result_pam_file_present
  when: '"pam" in ansible_facts.packages'
  tags:
  - CJIS-5.6.2.2
  - NIST-800-171-3.13.11
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(c)
  - NIST-800-53-IA-5(c)
  - PCI-DSS-Req-8.2.1
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.2
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - set_password_hashing_algorithm_systemauth

- name: Set PAM's Password Hashing Algorithm - Check the proper remediation for the
    system
  block:

  - name: Set PAM's Password Hashing Algorithm - Define the PAM file to be edited
      as a local fact
    ansible.builtin.set_fact:
      pam_file_path: /etc/pam.d/system-auth

  - name: Set PAM's Password Hashing Algorithm - Check if system relies on authselect
      tool
    ansible.builtin.stat:
      path: /usr/bin/authselect
    register: result_authselect_present

  - name: Set PAM's Password Hashing Algorithm - Ensure authselect custom profile
      is used if authselect is present
    block:

    - name: Set PAM's Password Hashing Algorithm - Check integrity of authselect current
        profile
      ansible.builtin.command:
        cmd: authselect check
      register: result_authselect_check_cmd
      changed_when: false
      failed_when: false

    - name: Set PAM's Password Hashing Algorithm - Informative message based on the
        authselect integrity check result
      ansible.builtin.assert:
        that:
        - result_authselect_check_cmd.rc == 0
        fail_msg:
        - authselect integrity check failed. Remediation aborted!
        - This remediation could not be applied because an authselect profile was
          not selected or the selected profile is not intact.
        - It is not recommended to manually edit the PAM files when authselect tool
          is available.
        - In cases where the default authselect profile does not cover a specific
          demand, a custom authselect profile is recommended.
        success_msg:
        - authselect integrity check passed

    - name: Set PAM's Password Hashing Algorithm - Get authselect current profile
      ansible.builtin.shell:
        cmd: authselect current -r | awk '{ print $1 }'
      register: result_authselect_profile
      changed_when: false
      when:
      - result_authselect_check_cmd is success

    - name: Set PAM's Password Hashing Algorithm - Define the current authselect profile
        as a local fact
      ansible.builtin.set_fact:
        authselect_current_profile: '{{ result_authselect_profile.stdout }}'
        authselect_custom_profile: '{{ result_authselect_profile.stdout }}'
      when:
      - result_authselect_profile is not skipped
      - result_authselect_profile.stdout is match("custom/")

    - name: Set PAM's Password Hashing Algorithm - Define the new authselect custom
        profile as a local fact
      ansible.builtin.set_fact:
        authselect_current_profile: '{{ result_authselect_profile.stdout }}'
        authselect_custom_profile: custom/hardening
      when:
      - result_authselect_profile is not skipped
      - result_authselect_profile.stdout is not match("custom/")

    - name: Set PAM's Password Hashing Algorithm - Get authselect current features
        to also enable them in the custom profile
      ansible.builtin.shell:
        cmd: authselect current | tail -n+3 | awk '{ print $2 }'
      register: result_authselect_features
      changed_when: false
      when:
      - result_authselect_profile is not skipped
      - authselect_current_profile is not match("custom/")

    - name: Set PAM's Password Hashing Algorithm - Check if any custom profile with
        the same name was already created
      ansible.builtin.stat:
        path: /etc/authselect/{{ authselect_custom_profile }}
      register: result_authselect_custom_profile_present
      changed_when: false
      when:
      - authselect_current_profile is not match("custom/")

    - name: Set PAM's Password Hashing Algorithm - Create an authselect custom profile
        based on the current profile
      ansible.builtin.command:
        cmd: authselect create-profile hardening -b {{ authselect_current_profile
          }}
      when:
      - result_authselect_check_cmd is success
      - authselect_current_profile is not match("custom/")
      - not result_authselect_custom_profile_present.stat.exists

    - name: Set PAM's Password Hashing Algorithm - Ensure authselect changes are applied
      ansible.builtin.command:
        cmd: authselect apply-changes -b --backup=before-hardening-custom-profile
      when:
      - result_authselect_check_cmd is success
      - result_authselect_profile is not skipped
      - authselect_current_profile is not match("custom/")
      - authselect_custom_profile is not match(authselect_current_profile)

    - name: Set PAM's Password Hashing Algorithm - Ensure the authselect custom profile
        is selected
      ansible.builtin.command:
        cmd: authselect select {{ authselect_custom_profile }}
      register: result_pam_authselect_select_profile
      when:
      - result_authselect_check_cmd is success
      - result_authselect_profile is not skipped
      - authselect_current_profile is not match("custom/")
      - authselect_custom_profile is not match(authselect_current_profile)

    - name: Set PAM's Password Hashing Algorithm - Restore the authselect features
        in the custom profile
      ansible.builtin.command:
        cmd: authselect enable-feature {{ item }}
      loop: '{{ result_authselect_features.stdout_lines }}'
      register: result_pam_authselect_restore_features
      when:
      - result_authselect_profile is not skipped
      - result_authselect_features is not skipped
      - result_pam_authselect_select_profile is not skipped

    - name: Set PAM's Password Hashing Algorithm - Ensure authselect changes are applied
      ansible.builtin.command:
        cmd: authselect apply-changes -b --backup=after-hardening-custom-profile
      when:
      - result_authselect_check_cmd is success
      - result_authselect_profile is not skipped
      - result_pam_authselect_restore_features is not skipped

    - name: Set PAM's Password Hashing Algorithm - Change the PAM file to be edited
        according to the custom authselect profile
      ansible.builtin.set_fact:
        pam_file_path: /etc/authselect/{{ authselect_custom_profile }}/{{ pam_file_path
          | basename }}
    when:
    - result_authselect_present.stat.exists

  - name: Set PAM's Password Hashing Algorithm - Define a fact for control already
      filtered in case filters are used
    ansible.builtin.set_fact:
      pam_module_control: sufficient

  - name: Set PAM's Password Hashing Algorithm - Check if expected PAM module line
      is present in {{ pam_file_path }}
    ansible.builtin.lineinfile:
      path: '{{ pam_file_path }}'
      regexp: ^\s*password\s+{{ pam_module_control | regex_escape() }}\s+pam_unix.so\s*.*
      state: absent
    check_mode: true
    changed_when: false
    register: result_pam_line_present

  - name: Set PAM's Password Hashing Algorithm - Include or update the PAM module
      line in {{ pam_file_path }}
    block:

    - name: Set PAM's Password Hashing Algorithm - Check if required PAM module line
        is present in {{ pam_file_path }} with different control
      ansible.builtin.lineinfile:
        path: '{{ pam_file_path }}'
        regexp: ^\s*password\s+.*\s+pam_unix.so\s*
        state: absent
      check_mode: true
      changed_when: false
      register: result_pam_line_other_control_present

    - name: Set PAM's Password Hashing Algorithm - Ensure the correct control for
        the required PAM module line in {{ pam_file_path }}
      ansible.builtin.replace:
        dest: '{{ pam_file_path }}'
        regexp: ^(\s*password\s+).*(\bpam_unix.so.*)
        replace: \1{{ pam_module_control }} \2
      register: result_pam_module_edit
      when:
      - result_pam_line_other_control_present.found == 1

    - name: Set PAM's Password Hashing Algorithm - Ensure the required PAM module
        line is included in {{ pam_file_path }}
      ansible.builtin.lineinfile:
        dest: '{{ pam_file_path }}'
        line: password    {{ pam_module_control }}    pam_unix.so
      register: result_pam_module_add
      when:
      - result_pam_line_other_control_present.found == 0 or result_pam_line_other_control_present.found
        > 1

    - name: Set PAM's Password Hashing Algorithm - Ensure authselect changes are applied
      ansible.builtin.command:
        cmd: authselect apply-changes -b
      when:
      - result_authselect_present is defined
      - result_authselect_present.stat.exists
      - |-
        (result_pam_module_add is defined and result_pam_module_add.changed)
         or (result_pam_module_edit is defined and result_pam_module_edit.changed)
    when:
    - result_pam_line_present.found is defined
    - result_pam_line_present.found == 0

  - name: Set PAM's Password Hashing Algorithm - Define a fact for control already
      filtered in case filters are used
    ansible.builtin.set_fact:
      pam_module_control: sufficient

  - name: Set PAM's Password Hashing Algorithm - Check if the required PAM module
      option is present in {{ pam_file_path }}
    ansible.builtin.lineinfile:
      path: '{{ pam_file_path }}'
      regexp: ^\s*password\s+{{ pam_module_control | regex_escape() }}\s+pam_unix.so\s*.*\s{{
        var_password_hashing_algorithm_pam }}\b
      state: absent
    check_mode: true
    changed_when: false
    register: result_pam_module_set_password_hashing_algorithm_systemauth_option_present

  - name: Set PAM's Password Hashing Algorithm - Ensure the "{{ var_password_hashing_algorithm_pam
      }}" PAM option for "pam_unix.so" is included in {{ pam_file_path }}
    ansible.builtin.lineinfile:
      path: '{{ pam_file_path }}'
      backrefs: true
      regexp: ^(\s*password\s+{{ pam_module_control | regex_escape() }}\s+pam_unix.so.*)
      line: \1 {{ var_password_hashing_algorithm_pam }}
      state: present
    register: result_pam_set_password_hashing_algorithm_systemauth_add
    when:
    - result_pam_module_set_password_hashing_algorithm_systemauth_option_present.found
      == 0

  - name: Set PAM's Password Hashing Algorithm - Ensure authselect changes are applied
    ansible.builtin.command:
      cmd: authselect apply-changes -b
    when:
    - result_authselect_present.stat.exists
    - |-
      (result_pam_set_password_hashing_algorithm_systemauth_add is defined and result_pam_set_password_hashing_algorithm_systemauth_add.changed)
       or (result_pam_set_password_hashing_algorithm_systemauth_edit is defined and result_pam_set_password_hashing_algorithm_systemauth_edit.changed)
  when:
  - '"pam" in ansible_facts.packages'
  - result_pam_file_present.stat.exists
  tags:
  - CJIS-5.6.2.2
  - NIST-800-171-3.13.11
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(c)
  - NIST-800-53-IA-5(c)
  - PCI-DSS-Req-8.2.1
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.2
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - set_password_hashing_algorithm_systemauth

- name: Set PAM's Password Hashing Algorithm - Check if /etc/pam.d/system-auth File
    is Present
  ansible.builtin.stat:
    path: /etc/pam.d/system-auth
  register: result_pam_file_present
  when: '"pam" in ansible_facts.packages'
  tags:
  - CJIS-5.6.2.2
  - NIST-800-171-3.13.11
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(c)
  - NIST-800-53-IA-5(c)
  - PCI-DSS-Req-8.2.1
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.2
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - set_password_hashing_algorithm_systemauth

- name: Set PAM's Password Hashing Algorithm - Check The Proper Remediation For The
    System
  block:

  - name: Set PAM's Password Hashing Algorithm - Define the PAM file to be edited
      as a local fact
    ansible.builtin.set_fact:
      pam_file_path: /etc/pam.d/system-auth

  - name: Set PAM's Password Hashing Algorithm - Check if system relies on authselect
      tool
    ansible.builtin.stat:
      path: /usr/bin/authselect
    register: result_authselect_present

  - name: Set PAM's Password Hashing Algorithm - Ensure authselect custom profile
      is used if authselect is present
    block:

    - name: Set PAM's Password Hashing Algorithm - Check integrity of authselect current
        profile
      ansible.builtin.command:
        cmd: authselect check
      register: result_authselect_check_cmd
      changed_when: false
      failed_when: false

    - name: Set PAM's Password Hashing Algorithm - Informative message based on the
        authselect integrity check result
      ansible.builtin.assert:
        that:
        - result_authselect_check_cmd.rc == 0
        fail_msg:
        - authselect integrity check failed. Remediation aborted!
        - This remediation could not be applied because an authselect profile was
          not selected or the selected profile is not intact.
        - It is not recommended to manually edit the PAM files when authselect tool
          is available.
        - In cases where the default authselect profile does not cover a specific
          demand, a custom authselect profile is recommended.
        success_msg:
        - authselect integrity check passed

    - name: Set PAM's Password Hashing Algorithm - Get authselect current profile
      ansible.builtin.shell:
        cmd: authselect current -r | awk '{ print $1 }'
      register: result_authselect_profile
      changed_when: false
      when:
      - result_authselect_check_cmd is success

    - name: Set PAM's Password Hashing Algorithm - Define the current authselect profile
        as a local fact
      ansible.builtin.set_fact:
        authselect_current_profile: '{{ result_authselect_profile.stdout }}'
        authselect_custom_profile: '{{ result_authselect_profile.stdout }}'
      when:
      - result_authselect_profile is not skipped
      - result_authselect_profile.stdout is match("custom/")

    - name: Set PAM's Password Hashing Algorithm - Define the new authselect custom
        profile as a local fact
      ansible.builtin.set_fact:
        authselect_current_profile: '{{ result_authselect_profile.stdout }}'
        authselect_custom_profile: custom/hardening
      when:
      - result_authselect_profile is not skipped
      - result_authselect_profile.stdout is not match("custom/")

    - name: Set PAM's Password Hashing Algorithm - Get authselect current features
        to also enable them in the custom profile
      ansible.builtin.shell:
        cmd: authselect current | tail -n+3 | awk '{ print $2 }'
      register: result_authselect_features
      changed_when: false
      when:
      - result_authselect_profile is not skipped
      - authselect_current_profile is not match("custom/")

    - name: Set PAM's Password Hashing Algorithm - Check if any custom profile with
        the same name was already created
      ansible.builtin.stat:
        path: /etc/authselect/{{ authselect_custom_profile }}
      register: result_authselect_custom_profile_present
      changed_when: false
      when:
      - authselect_current_profile is not match("custom/")

    - name: Set PAM's Password Hashing Algorithm - Create an authselect custom profile
        based on the current profile
      ansible.builtin.command:
        cmd: authselect create-profile hardening -b {{ authselect_current_profile
          }}
      when:
      - result_authselect_check_cmd is success
      - authselect_current_profile is not match("custom/")
      - not result_authselect_custom_profile_present.stat.exists

    - name: Set PAM's Password Hashing Algorithm - Ensure authselect changes are applied
      ansible.builtin.command:
        cmd: authselect apply-changes -b --backup=before-hardening-custom-profile
      when:
      - result_authselect_check_cmd is success
      - result_authselect_profile is not skipped
      - authselect_current_profile is not match("custom/")
      - authselect_custom_profile is not match(authselect_current_profile)

    - name: Set PAM's Password Hashing Algorithm - Ensure the authselect custom profile
        is selected
      ansible.builtin.command:
        cmd: authselect select {{ authselect_custom_profile }}
      register: result_pam_authselect_select_profile
      when:
      - result_authselect_check_cmd is success
      - result_authselect_profile is not skipped
      - authselect_current_profile is not match("custom/")
      - authselect_custom_profile is not match(authselect_current_profile)

    - name: Set PAM's Password Hashing Algorithm - Restore the authselect features
        in the custom profile
      ansible.builtin.command:
        cmd: authselect enable-feature {{ item }}
      loop: '{{ result_authselect_features.stdout_lines }}'
      register: result_pam_authselect_restore_features
      when:
      - result_authselect_profile is not skipped
      - result_authselect_features is not skipped
      - result_pam_authselect_select_profile is not skipped

    - name: Set PAM's Password Hashing Algorithm - Ensure authselect changes are applied
      ansible.builtin.command:
        cmd: authselect apply-changes -b --backup=after-hardening-custom-profile
      when:
      - result_authselect_check_cmd is success
      - result_authselect_profile is not skipped
      - result_pam_authselect_restore_features is not skipped

    - name: Set PAM's Password Hashing Algorithm - Change the PAM file to be edited
        according to the custom authselect profile
      ansible.builtin.set_fact:
        pam_file_path: /etc/authselect/{{ authselect_custom_profile }}/{{ pam_file_path
          | basename }}
    when:
    - result_authselect_present.stat.exists

  - name: Set PAM's Password Hashing Algorithm - Ensure That Only the Correct Hashing
      Algorithm Option For pam_unix.so Is Used in /etc/pam.d/system-auth
    ansible.builtin.replace:
      dest: '{{ pam_file_path }}'
      regexp: (^\s*password.*pam_unix\.so.*)\b{{ item }}\b\s*(.*)
      replace: \1\2
    when: item != var_password_hashing_algorithm_pam
    loop:
    - sha512
    - yescrypt
    - gost_yescrypt
    - blowfish
    - sha256
    - md5
    - bigcrypt
    register: result_pam_hashing_options_removal

  - name: Set PAM's Password Hashing Algorithm - Ensure authselect changes are applied
    ansible.builtin.command:
      cmd: authselect apply-changes -b
    when:
    - result_authselect_present.stat.exists
    - result_pam_hashing_options_removal is changed
  when:
  - '"pam" in ansible_facts.packages'
  - result_pam_file_present.stat.exists
  tags:
  - CJIS-5.6.2.2
  - NIST-800-171-3.13.11
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(c)
  - NIST-800-53-IA-5(c)
  - PCI-DSS-Req-8.2.1
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.2
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - set_password_hashing_algorithm_systemauth

Remediation Shell script ⇲

# Remediation is applicable only in certain platforms
if rpm --quiet -q pam; then

var_password_hashing_algorithm_pam='sha512'


PAM_FILE_PATH="/etc/pam.d/system-auth"
CONTROL="sufficient"

if [ -e "$PAM_FILE_PATH" ] ; then
    PAM_FILE_PATH="$PAM_FILE_PATH"
    if [ -f /usr/bin/authselect ]; then
        
        if ! authselect check; then
        echo "
        authselect integrity check failed. Remediation aborted!
        This remediation could not be applied because an authselect profile was not selected or the selected profile is not intact.
        It is not recommended to manually edit the PAM files when authselect tool is available.
        In cases where the default authselect profile does not cover a specific demand, a custom authselect profile is recommended."
        exit 1
        fi

        CURRENT_PROFILE=$(authselect current -r | awk '{ print $1 }')
        # If not already in use, a custom profile is created preserving the enabled features.
        if [[ ! $CURRENT_PROFILE == custom/* ]]; then
            ENABLED_FEATURES=$(authselect current | tail -n+3 | awk '{ print $2 }')
            authselect create-profile hardening -b $CURRENT_PROFILE
            CURRENT_PROFILE="custom/hardening"
            
            authselect apply-changes -b --backup=before-hardening-custom-profile
            authselect select $CURRENT_PROFILE
            for feature in $ENABLED_FEATURES; do
                authselect enable-feature $feature;
            done
            
            authselect apply-changes -b --backup=after-hardening-custom-profile
        fi
        PAM_FILE_NAME=$(basename "$PAM_FILE_PATH")
        PAM_FILE_PATH="/etc/authselect/$CURRENT_PROFILE/$PAM_FILE_NAME"

        authselect apply-changes -b
    fi
    

        if ! grep -qP "^\s*password\s+\$CONTROL\s+pam_unix.so\s*.*" "$PAM_FILE_PATH"; then
            # Line matching group + control + module was not found. Check group + module.
            if [ "$(grep -cP '^\s*password\s+.*\s+pam_unix.so\s*' "$PAM_FILE_PATH")" -eq 1 ]; then
                # The control is updated only if one single line matches.
                sed -i -E --follow-symlinks "s/^(\s*password\s+).*(\bpam_unix.so.*)/\1$CONTROL \2/" "$PAM_FILE_PATH"
            else
                echo "password    $CONTROL    pam_unix.so" >> "$PAM_FILE_PATH"
            fi
        fi
        # Check the option
        if ! grep -qP "^\s*password\s+\$CONTROL\s+pam_unix.so\s*.*\s$var_password_hashing_algorithm_pam\b" "$PAM_FILE_PATH"; then
            sed -i -E --follow-symlinks "/\s*password\s+\$CONTROL\s+pam_unix.so.*/ s/$/ $var_password_hashing_algorithm_pam/" "$PAM_FILE_PATH"
        fi
    if [ -f /usr/bin/authselect ]; then
        
        authselect apply-changes -b
    fi
else
    echo "$PAM_FILE_PATH was not found" >&2
fi

# Ensure only the correct hashing algorithm option is used.
declare -a HASHING_ALGORITHMS_OPTIONS=("sha512" "yescrypt" "gost_yescrypt" "blowfish" "sha256" "md5" "bigcrypt")

for hash_option in "${HASHING_ALGORITHMS_OPTIONS[@]}"; do
  if [ "$hash_option" != "$var_password_hashing_algorithm_pam" ]; then
    if grep -qP "^\s*password\s+.*\s+pam_unix.so\s+.*\b$hash_option\b" "$PAM_FILE_PATH"; then
      if [ -e "$PAM_FILE_PATH" ] ; then
    PAM_FILE_PATH="$PAM_FILE_PATH"
    if [ -f /usr/bin/authselect ]; then
        
        if ! authselect check; then
        echo "
        authselect integrity check failed. Remediation aborted!
        This remediation could not be applied because an authselect profile was not selected or the selected profile is not intact.
        It is not recommended to manually edit the PAM files when authselect tool is available.
        In cases where the default authselect profile does not cover a specific demand, a custom authselect profile is recommended."
        exit 1
        fi

        CURRENT_PROFILE=$(authselect current -r | awk '{ print $1 }')
        # If not already in use, a custom profile is created preserving the enabled features.
        if [[ ! $CURRENT_PROFILE == custom/* ]]; then
            ENABLED_FEATURES=$(authselect current | tail -n+3 | awk '{ print $2 }')
            authselect create-profile hardening -b $CURRENT_PROFILE
            CURRENT_PROFILE="custom/hardening"
            
            authselect apply-changes -b --backup=before-hardening-custom-profile
            authselect select $CURRENT_PROFILE
            for feature in $ENABLED_FEATURES; do
                authselect enable-feature $feature;
            done
            
            authselect apply-changes -b --backup=after-hardening-custom-profile
        fi
        PAM_FILE_NAME=$(basename "$PAM_FILE_PATH")
        PAM_FILE_PATH="/etc/authselect/$CURRENT_PROFILE/$PAM_FILE_NAME"

        authselect apply-changes -b
    fi
    
if grep -qP "^\s*password\s+.*\s+pam_unix.so\s.*\b$hash_option\b" "$PAM_FILE_PATH"; then
    sed -i -E --follow-symlinks "s/(.*password.*.*.*pam_unix.so.*)\s$hash_option=?[[:alnum:]]*(.*)/\1\2/g" "$PAM_FILE_PATH"
fi
    if [ -f /usr/bin/authselect ]; then
        
        authselect apply-changes -b
    fi
else
    echo "$PAM_FILE_PATH was not found" >&2
fi
    fi
  fi
done

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Group Protect Accounts by Restricting Password-Based Login Group contains 3 groups and 10 rules

[ref] Conventionally, Unix shell accounts are accessed by providing a username and password to a login program, which tests these values for correctness using the /etc/passwd and /etc/shadow files. Password-based login is vulnerable to guessing of weak passwords, and to sniffing and man-in-the-middle attacks against passwords entered over a network or at an insecure console. Therefore, mechanisms for accessing accounts by entering usernames and passwords should be restricted to those which are operationally necessary.

Group Set Account Expiration Parameters Group contains 1 rule

[ref] Accounts can be configured to be automatically disabled after a certain time period, meaning that they will require administrator interaction to become usable again. Expiration of accounts after inactivity can be set for all accounts by default and also on a per-account basis, such as for accounts that are known to be temporary. To configure automatic expiration of an account following the expiration of its password (that is, after the password has expired and not been changed), run the following command, substituting NUM_DAYS and USER appropriately:

$ sudo chage -I NUM_DAYS USER

Accounts, such as temporary accounts, can also be configured to expire on an explicitly-set date with the -E option. The file /etc/default/useradd controls default settings for all newly-created accounts created with the system's normal command line utilities.

Warning: This will only apply to newly created accounts

Rule Ensure All Accounts on the System Have Unique Names [ref]

Ensure accounts on the system have unique names. To ensure all accounts have unique names, run the following command:

$ sudo getent passwd | awk -F: '{ print $1}' | uniq -d

If a username is returned, change or delete the username.

Rationale:

Unique usernames allow for accountability on the system.

Severity:

medium

Rule ID:

xccdf_org.ssgproject.content_rule_account_unique_name

References:

cjis	5.5.2
disa	CCI-000770, CCI-000804
pcidss	Req-8.1.1
pcidss4	8.2.1, 8.2

Group Verify Proper Storage and Existence of Password Hashes Group contains 3 rules

[ref] By default, password hashes for local accounts are stored in the second field (colon-separated) in /etc/shadow. This file should be readable only by processes running with root credentials, preventing users from casually accessing others' password hashes and attempting to crack them. However, it remains possible to misconfigure the system and store password hashes in world-readable files such as /etc/passwd, or to even store passwords themselves in plaintext on the system. Using system-provided tools for password change/creation should allow administrators to avoid such misconfiguration.

Rule All GIDs referenced in /etc/passwd must be defined in /etc/group [ref]

Add a group to the system for each GID referenced without a corresponding group.

Rationale:

If a user is assigned the Group Identifier (GID) of a group not existing on the system, and a group with the Group Identifier (GID) is subsequently created, the user may have unintended rights to any files associated with the group.

Severity:

low

Rule ID:

xccdf_org.ssgproject.content_rule_gid_passwd_group_same

References:

cis-csc	1, 12, 15, 16, 5
cjis	5.5.2
cobit5	DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.03, DSS06.10
disa	CCI-000764
isa-62443-2009	4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.2, 4.3.3.7.4
isa-62443-2013	SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.1
iso27001-2013	A.18.1.4, A.7.1.1, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.2, A.9.4.3
nerc-cip	CIP-003-8 R5.1.1, CIP-003-8 R5.3, CIP-004-6 R2.2.3, CIP-004-6 R2.3, CIP-007-3 R5.1, CIP-007-3 R5.1.2, CIP-007-3 R5.2, CIP-007-3 R5.3.1, CIP-007-3 R5.3.2, CIP-007-3 R5.3.3
nist	IA-2, CM-6(a)
nist-csf	PR.AC-1, PR.AC-6, PR.AC-7
pcidss	Req-8.5.a
os-srg	SRG-OS-000104-GPOS-00051
pcidss4	8.2.2, 8.2

Rule Prevent Login to Accounts With Empty Password [ref]

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.

Warning: If the system relies on authselect tool to manage PAM settings, the remediation will also use authselect tool. However, if any manual modification was made in PAM files, the authselect integrity check will fail and the remediation will be aborted in order to preserve intentional changes. In this case, an informative message will be shown in the remediation report. Note that this rule is not applicable for systems running within a container. Having user with empty password within a container is not considered a risk, because it should not be possible to directly login into a container anyway.

Rationale:

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.

Severity:

high

Rule ID: xccdf_org.ssgproject.content_rule_no_empty_passwords

References:

cis-csc	1, 12, 13, 14, 15, 16, 18, 3, 5
cjis	5.5.2
cobit5	APO01.06, DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.02, DSS06.03, DSS06.10
cui	3.1.1, 3.1.5
disa	CCI-000366
hipaa	164.308(a)(1)(ii)(B), 164.308(a)(7)(i), 164.308(a)(7)(ii)(A), 164.310(a)(1), 164.310(a)(2)(i), 164.310(a)(2)(ii), 164.310(a)(2)(iii), 164.310(b), 164.310(c), 164.310(d)(1), 164.310(d)(2)(iii)
isa-62443-2009	4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4
isa-62443-2013	SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 5.2
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.18.1.4, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.1, A.9.4.2, A.9.4.3, A.9.4.4, A.9.4.5
nist	IA-5(1)(a), IA-5(c), CM-6(a)
nist-csf	PR.AC-1, PR.AC-4, PR.AC-6, PR.AC-7, PR.DS-5
ospp	FIA_UAU.1
pcidss	Req-8.2.3
os-srg	SRG-OS-000480-GPOS-00227
pcidss4	8.3.1, 8.3

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.5.2
  - NIST-800-171-3.1.1
  - NIST-800-171-3.1.5
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(a)
  - NIST-800-53-IA-5(c)
  - PCI-DSS-Req-8.2.3
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.1
  - configure_strategy
  - high_severity
  - low_complexity
  - medium_disruption
  - no_empty_passwords
  - no_reboot_needed

- name: Prevent Login to Accounts With Empty Password - Check if system relies on
    authselect
  ansible.builtin.stat:
    path: /usr/bin/authselect
  register: result_authselect_present
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.5.2
  - NIST-800-171-3.1.1
  - NIST-800-171-3.1.5
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(a)
  - NIST-800-53-IA-5(c)
  - PCI-DSS-Req-8.2.3
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.1
  - configure_strategy
  - high_severity
  - low_complexity
  - medium_disruption
  - no_empty_passwords
  - no_reboot_needed

- name: Prevent Login to Accounts With Empty Password - Remediate using authselect
  block:

  - name: Prevent Login to Accounts With Empty Password - Check integrity of authselect
      current profile
    ansible.builtin.command:
      cmd: authselect check
    register: result_authselect_check_cmd
    changed_when: false
    failed_when: false

  - name: Prevent Login to Accounts With Empty Password - Informative message based
      on the authselect integrity check result
    ansible.builtin.assert:
      that:
      - result_authselect_check_cmd.rc == 0
      fail_msg:
      - authselect integrity check failed. Remediation aborted!
      - This remediation could not be applied because an authselect profile was not
        selected or the selected profile is not intact.
      - It is not recommended to manually edit the PAM files when authselect tool
        is available.
      - In cases where the default authselect profile does not cover a specific demand,
        a custom authselect profile is recommended.
      success_msg:
      - authselect integrity check passed

  - name: Prevent Login to Accounts With Empty Password - Get authselect current features
    ansible.builtin.shell:
      cmd: authselect current | tail -n+3 | awk '{ print $2 }'
    register: result_authselect_features
    changed_when: false
    when:
    - result_authselect_check_cmd is success

  - name: Prevent Login to Accounts With Empty Password - Ensure "without-nullok"
      feature is enabled using authselect tool
    ansible.builtin.command:
      cmd: authselect enable-feature without-nullok
    register: result_authselect_enable_feature_cmd
    when:
    - result_authselect_check_cmd is success
    - result_authselect_features.stdout is not search("without-nullok")

  - name: Prevent Login to Accounts With Empty Password - Ensure authselect changes
      are applied
    ansible.builtin.command:
      cmd: authselect apply-changes -b
    when:
    - result_authselect_enable_feature_cmd is not skipped
    - result_authselect_enable_feature_cmd is success
  when:
  - '"kernel" in ansible_facts.packages'
  - result_authselect_present.stat.exists
  tags:
  - CJIS-5.5.2
  - NIST-800-171-3.1.1
  - NIST-800-171-3.1.5
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(a)
  - NIST-800-53-IA-5(c)
  - PCI-DSS-Req-8.2.3
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.1
  - configure_strategy
  - high_severity
  - low_complexity
  - medium_disruption
  - no_empty_passwords
  - no_reboot_needed

- name: Prevent Login to Accounts With Empty Password - Remediate directly editing
    PAM files
  ansible.builtin.replace:
    dest: '{{ item }}'
    regexp: nullok
  loop:
  - /etc/pam.d/system-auth
  - /etc/pam.d/password-auth
  when:
  - '"kernel" in ansible_facts.packages'
  - not result_authselect_present.stat.exists
  tags:
  - CJIS-5.5.2
  - NIST-800-171-3.1.1
  - NIST-800-171-3.1.5
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-5(1)(a)
  - NIST-800-53-IA-5(c)
  - PCI-DSS-Req-8.2.3
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.1
  - configure_strategy
  - high_severity
  - low_complexity
  - medium_disruption
  - no_empty_passwords
  - no_reboot_needed

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,%23%20Generated%20by%20authselect%20on%20Sat%20Oct%2027%2014%3A59%3A36%202018%0A%23%20Do%20not%20modify%20this%20file%20manually.%0A%0Aauth%20%20%20%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_env.so%0Aauth%20%20%20%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_faildelay.so%20delay%3D2000000%0Aauth%20%20%20%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_fprintd.so%0Aauth%20%20%20%20%20%20%20%20%5Bdefault%3D1%20ignore%3Dignore%20success%3Dok%5D%20%20%20%20%20%20%20%20%20pam_succeed_if.so%20uid%20%3E%3D%201000%20quiet%0Aauth%20%20%20%20%20%20%20%20%5Bdefault%3D1%20ignore%3Dignore%20success%3Dok%5D%20%20%20%20%20%20%20%20%20pam_localuser.so%0Aauth%20%20%20%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_unix.so%20try_first_pass%0Aauth%20%20%20%20%20%20%20%20requisite%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_succeed_if.so%20uid%20%3E%3D%201000%20quiet_success%0Aauth%20%20%20%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_sss.so%20forward_pass%0Aauth%20%20%20%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_deny.so%0A%0Aaccount%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_unix.so%0Aaccount%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_localuser.so%0Aaccount%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_succeed_if.so%20uid%20%3C%201000%20quiet%0Aaccount%20%20%20%20%20%5Bdefault%3Dbad%20success%3Dok%20user_unknown%3Dignore%5D%20pam_sss.so%0Aaccount%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_permit.so%0A%0Apassword%20%20%20%20requisite%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_pwquality.so%20try_first_pass%20local_users_only%0Apassword%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_unix.so%20sha512%20shadow%20try_first_pass%20use_authtok%0Apassword%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_sss.so%20use_authtok%0Apassword%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_deny.so%0A%0Asession%20%20%20%20%20optional%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_keyinit.so%20revoke%0Asession%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_limits.so%0A-session%20%20%20%20optional%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_systemd.so%0Asession%20%20%20%20%20%5Bsuccess%3D1%20default%3Dignore%5D%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_succeed_if.so%20service%20in%20crond%20quiet%20use_uid%0Asession%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_unix.so%0Asession%20%20%20%20%20optional%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_sss.so%0A
        mode: 0644
        path: /etc/pam.d/password-auth
        overwrite: true
      - contents:
          source: data:,%23%20Generated%20by%20authselect%20on%20Sat%20Oct%2027%2014%3A59%3A36%202018%0A%23%20Do%20not%20modify%20this%20file%20manually.%0A%0Aauth%20%20%20%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_env.so%0Aauth%20%20%20%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_faildelay.so%20delay%3D2000000%0Aauth%20%20%20%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_fprintd.so%0Aauth%20%20%20%20%20%20%20%20%5Bdefault%3D1%20ignore%3Dignore%20success%3Dok%5D%20%20%20%20%20%20%20%20%20pam_succeed_if.so%20uid%20%3E%3D%201000%20quiet%0Aauth%20%20%20%20%20%20%20%20%5Bdefault%3D1%20ignore%3Dignore%20success%3Dok%5D%20%20%20%20%20%20%20%20%20pam_localuser.so%0Aauth%20%20%20%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_unix.so%20try_first_pass%0Aauth%20%20%20%20%20%20%20%20requisite%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_succeed_if.so%20uid%20%3E%3D%201000%20quiet_success%0Aauth%20%20%20%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_sss.so%20forward_pass%0Aauth%20%20%20%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_deny.so%0A%0Aaccount%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_unix.so%0Aaccount%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_localuser.so%0Aaccount%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_succeed_if.so%20uid%20%3C%201000%20quiet%0Aaccount%20%20%20%20%20%5Bdefault%3Dbad%20success%3Dok%20user_unknown%3Dignore%5D%20pam_sss.so%0Aaccount%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_permit.so%0A%0Apassword%20%20%20%20requisite%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_pwquality.so%20try_first_pass%20local_users_only%0Apassword%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_unix.so%20sha512%20shadow%20try_first_pass%20use_authtok%0Apassword%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_sss.so%20use_authtok%0Apassword%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_deny.so%0A%0Asession%20%20%20%20%20optional%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_keyinit.so%20revoke%0Asession%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_limits.so%0A-session%20%20%20%20optional%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_systemd.so%0Asession%20%20%20%20%20%5Bsuccess%3D1%20default%3Dignore%5D%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_succeed_if.so%20service%20in%20crond%20quiet%20use_uid%0Asession%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_unix.so%0Asession%20%20%20%20%20optional%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_sss.so%0A
        mode: 0644
        path: /etc/pam.d/system-auth
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	false
Strategy:	configure

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

if [ -f /usr/bin/authselect ]; then
    if ! authselect check; then
echo "
authselect integrity check failed. Remediation aborted!
This remediation could not be applied because an authselect profile was not selected or the selected profile is not intact.
It is not recommended to manually edit the PAM files when authselect tool is available.
In cases where the default authselect profile does not cover a specific demand, a custom authselect profile is recommended."
exit 1
fi
authselect enable-feature without-nullok

authselect apply-changes -b
else
    
if grep -qP "^\s*auth\s+sufficient\s+pam_unix.so\s.*\bnullok\b" "/etc/pam.d/system-auth"; then
    sed -i -E --follow-symlinks "s/(.*auth.*sufficient.*pam_unix.so.*)\snullok=?[[:alnum:]]*(.*)/\1\2/g" "/etc/pam.d/system-auth"
fi
    
if grep -qP "^\s*password\s+sufficient\s+pam_unix.so\s.*\bnullok\b" "/etc/pam.d/system-auth"; then
    sed -i -E --follow-symlinks "s/(.*password.*sufficient.*pam_unix.so.*)\snullok=?[[:alnum:]]*(.*)/\1\2/g" "/etc/pam.d/system-auth"
fi
    
if grep -qP "^\s*auth\s+sufficient\s+pam_unix.so\s.*\bnullok\b" "/etc/pam.d/password-auth"; then
    sed -i -E --follow-symlinks "s/(.*auth.*sufficient.*pam_unix.so.*)\snullok=?[[:alnum:]]*(.*)/\1\2/g" "/etc/pam.d/password-auth"
fi
    
if grep -qP "^\s*password\s+sufficient\s+pam_unix.so\s.*\bnullok\b" "/etc/pam.d/password-auth"; then
    sed -i -E --follow-symlinks "s/(.*password.*sufficient.*pam_unix.so.*)\snullok=?[[:alnum:]]*(.*)/\1\2/g" "/etc/pam.d/password-auth"
fi
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Ensure There Are No Accounts With Blank or Null Passwords [ref]

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]

Warning: Note that this rule is not applicable for systems running within a container. Having user with empty password within a container is not considered a risk, because it should not be possible to directly login into a container anyway.

Rationale:

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.

Severity:

high

Rule ID: xccdf_org.ssgproject.content_rule_no_empty_passwords_etc_shadow

References:

disa	CCI-000366
nist	CM-6(b), CM-6.1(iv)
os-srg	SRG-OS-000480-GPOS-00227
pcidss4	2.2.2, 2.2

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-53-CM-6(b)
  - NIST-800-53-CM-6.1(iv)
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.2
  - high_severity
  - low_complexity
  - low_disruption
  - no_empty_passwords_etc_shadow
  - no_reboot_needed
  - restrict_strategy

- name: Collect users with no password
  command: |
    awk -F: '!$2 {print $1}' /etc/shadow
  register: users_nopasswd
  changed_when: false
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-53-CM-6(b)
  - NIST-800-53-CM-6.1(iv)
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.2
  - high_severity
  - low_complexity
  - low_disruption
  - no_empty_passwords_etc_shadow
  - no_reboot_needed
  - restrict_strategy

- name: Lock users with no password
  command: |
    passwd -l {{ item }}
  with_items: '{{ users_nopasswd.stdout_lines }}'
  when:
  - '"kernel" in ansible_facts.packages'
  - users_nopasswd is not skipped and users_nopasswd.stdout_lines | length > 0
  tags:
  - NIST-800-53-CM-6(b)
  - NIST-800-53-CM-6.1(iv)
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.2
  - high_severity
  - low_complexity
  - low_disruption
  - no_empty_passwords_etc_shadow
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

readarray -t users_with_empty_pass < <(sudo awk -F: '!$2 {print $1}' /etc/shadow)

for user_with_empty_pass in "${users_with_empty_pass[@]}"
do
    passwd -l $user_with_empty_pass
done

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Group Restrict Root Logins Group contains 3 rules

[ref] Direct root logins should be allowed only for emergency use. In normal situations, the administrator should access the system via a unique unprivileged account, and then use su or sudo to execute privileged commands. Discouraging administrators from accessing the root account directly ensures an audit trail in organizations with multiple administrators. Locking down the channels through which root can connect directly also reduces opportunities for password-guessing against the root account. The login program uses the file /etc/securetty to determine which interfaces should allow root logins. The virtual devices /dev/console and /dev/tty* represent the system consoles (accessible via the Ctrl-Alt-F1 through Ctrl-Alt-F6 keyboard sequences on a default installation). The default securetty file also contains /dev/vc/*. These are likely to be deprecated in most environments, but may be retained for compatibility. Root should also be prohibited from connecting via network protocols. Other sections of this document include guidance describing how to prevent root from logging in via SSH.

Rule Verify Only Root Has UID 0 [ref]

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.

Rationale:

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.

Severity:

high

Rule ID: xccdf_org.ssgproject.content_rule_accounts_no_uid_except_zero

References:

cis-csc	1, 12, 13, 14, 15, 16, 18, 3, 5
cobit5	APO01.06, DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.02, DSS06.03, DSS06.10
cui	3.1.1, 3.1.5
disa	CCI-000366
isa-62443-2009	4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4
isa-62443-2013	SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 5.2
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.18.1.4, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.1, A.9.4.2, A.9.4.3, A.9.4.4, A.9.4.5
nerc-cip	CIP-003-8 R5.1.1, CIP-003-8 R5.3, CIP-004-6 R2.2.3, CIP-004-6 R2.3, CIP-007-3 R5.1, CIP-007-3 R5.1.2, CIP-007-3 R5.2, CIP-007-3 R5.3.1, CIP-007-3 R5.3.2, CIP-007-3 R5.3.3
nist	IA-2, AC-6(5), IA-4(b)
nist-csf	PR.AC-1, PR.AC-4, PR.AC-6, PR.AC-7, PR.DS-5
pcidss	Req-8.5
os-srg	SRG-OS-000480-GPOS-00227
pcidss4	8.2.1, 8.2

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Get all /etc/passwd file entries
  getent:
    database: passwd
    split: ':'
  tags:
  - NIST-800-171-3.1.1
  - NIST-800-171-3.1.5
  - NIST-800-53-AC-6(5)
  - NIST-800-53-IA-2
  - NIST-800-53-IA-4(b)
  - PCI-DSS-Req-8.5
  - PCI-DSSv4-8.2
  - PCI-DSSv4-8.2.1
  - accounts_no_uid_except_zero
  - high_severity
  - low_complexity
  - low_disruption
  - no_reboot_needed
  - restrict_strategy

- name: Lock the password of the user accounts other than root with uid 0
  command: passwd -l {{ item.key }}
  loop: '{{ getent_passwd | dict2items | rejectattr(''key'', ''search'', ''root'')
    | list }}'
  when: item.value.1  == '0'
  tags:
  - NIST-800-171-3.1.1
  - NIST-800-171-3.1.5
  - NIST-800-53-AC-6(5)
  - NIST-800-53-IA-2
  - NIST-800-53-IA-4(b)
  - PCI-DSS-Req-8.5
  - PCI-DSSv4-8.2
  - PCI-DSSv4-8.2.1
  - accounts_no_uid_except_zero
  - high_severity
  - low_complexity
  - low_disruption
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲

awk -F: '$3 == 0 && $1 != "root" { print $1 }' /etc/passwd | xargs --no-run-if-empty --max-lines=1 passwd -l

Rule Verify Root Has A Primary GID 0 [ref]

The root user should have a primary group of 0.

Rationale:

To help ensure that root-owned files are not inadvertently exposed to other users.

Severity:

high

Rule ID: xccdf_org.ssgproject.content_rule_accounts_root_gid_zero

References:

pcidss	Req-8.1.1
pcidss4	8.2.1, 8.2

Rule Enforce usage of pam_wheel for su authentication [ref]

To ensure that only users who are members of the wheel group can run commands with altered privileges through the su command, make sure that the following line exists in the file /etc/pam.d/su:

auth required pam_wheel.so use_uid

Warning: Members of "wheel" or GID 0 groups are checked by default if the group option is not set for pam_wheel.so module. Therefore, members of these groups should be manually checked or a different group should be informed according to the site policy.

Rationale:

The su program allows to run commands with a substitute user and group ID. It is commonly used to run commands as the root user. Limiting access to such command is considered a good security practice.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_use_pam_wheel_for_su

References:

disa	CCI-002165, CCI-004895
ospp	FMT_SMF_EXT.1.1
os-srg	SRG-OS-000373-GPOS-00156, SRG-OS-000312-GPOS-00123

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - use_pam_wheel_for_su

- name: Restrict usage of su command only to members of wheel group
  replace:
    path: /etc/pam.d/su
    regexp: ^[\s]*#[\s]*auth[\s]+required[\s]+pam_wheel\.so[\s]+use_uid$
    replace: auth             required        pam_wheel.so use_uid
  when: '"pam" in ansible_facts.packages'
  tags:
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - use_pam_wheel_for_su

Remediation Shell script ⇲

# Remediation is applicable only in certain platforms
if rpm --quiet -q pam; then

# uncomment the option if commented
sed '/^[[:space:]]*#[[:space:]]*auth[[:space:]]\+required[[:space:]]\+pam_wheel\.so[[:space:]]\+use_uid$/s/^[[:space:]]*#//' -i /etc/pam.d/su

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Ensure All Accounts on the System Have Unique User IDs [ref]

Change user IDs (UIDs), or delete accounts, so each has a unique name.

Warning: Automatic remediation of this control is not available due to unique requirements of each system.

Rationale:

To assure accountability and prevent unauthenticated access, interactive users must be identified and authenticated to prevent potential misuse and compromise of the system.

Severity:

medium

Rule ID:

xccdf_org.ssgproject.content_rule_account_unique_id

References:

disa	CCI-000135, CCI-000764, CCI-000804
pcidss	Req-8.1.1
os-srg	SRG-OS-000104-GPOS-00051, SRG-OS-000121-GPOS-00062
pcidss4	8.2.1, 8.2

Rule Ensure All Groups on the System Have Unique Group ID [ref]

Change the group name or delete groups, so each has a unique id.

Warning: Automatic remediation of this control is not available due to the unique requirements of each system.

Rationale:

To assure accountability and prevent unauthenticated access, groups must be identified uniquely to prevent potential misuse and compromise of the system.

Severity:

medium

Rule ID:

xccdf_org.ssgproject.content_rule_group_unique_id

References:

disa	CCI-000764
os-srg	SRG-OS-000104-GPOS-00051
pcidss4	8.2.1, 8.2

Rule Ensure All Groups on the System Have Unique Group Names [ref]

Change the group name or delete groups, so each has a unique name.

Warning: Automatic remediation of this control is not available due to the unique requirements of each system.

Rationale:

To assure accountability and prevent unauthenticated access, groups must be identified uniquely to prevent potential misuse and compromise of the system.

Severity:

medium

Rule ID:

xccdf_org.ssgproject.content_rule_group_unique_name

References:

pcidss4	8.2.1, 8.2

Group Secure Session Configuration Files for Login Accounts Group contains 2 groups and 10 rules

[ref] When a user logs into a Unix account, the system configures the user's session by reading a number of files. Many of these files are located in the user's home directory, and may have weak permissions as a result of user error or misconfiguration. If an attacker can modify or even read certain types of account configuration information, they can often gain full access to the affected user's account. Therefore, it is important to test and correct configuration file permissions for interactive accounts, particularly those of privileged users such as root or system administrators.

Group Ensure that No Dangerous Directories Exist in Root's Path Group contains 1 rule

[ref] The active path of the root account can be obtained by starting a new root shell and running:

# echo $PATH

This will produce a colon-separated list of directories in the path.

Certain path elements could be considered dangerous, as they could lead to root executing unknown or untrusted programs, which could contain malicious code. Since root may sometimes work inside untrusted directories, the . character, which represents the current directory, should never be in the root path, nor should any directory which can be written to by an unprivileged or semi-privileged (system) user.

It is a good practice for administrators to always execute privileged commands by typing the full path to the command.

Rule Ensure that Root's Path Does Not Include World or Group-Writable Directories [ref]

For each element in root's path, run:

# ls -ld DIR

and ensure that write permissions are disabled for group and other.

Rationale:

Such entries increase the risk that root could execute code provided by unprivileged users, and potentially malicious code.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_accounts_root_path_dirs_no_write

References:

cis-csc	11, 3, 9
cobit5	BAI10.01, BAI10.02, BAI10.03, BAI10.05
disa	CCI-000366
isa-62443-2009	4.3.4.3.2, 4.3.4.3.3
isa-62443-2013	SR 7.6
iso27001-2013	A.12.1.2, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4
nist	CM-6(a), CM-6(a)
nist-csf	PR.IP-1

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	false
Strategy:	restrict

- name: Get root paths which are not symbolic links
  stat:
    path: '{{ item }}'
  changed_when: false
  failed_when: false
  register: root_paths
  with_items: '{{ ansible_env.PATH.split('':'') }}'
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-6(a)
  - accounts_root_path_dirs_no_write
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Disable writability to root directories
  file:
    path: '{{ item.item }}'
    mode: g-w,o-w
  with_items: '{{ root_paths.results }}'
  when:
  - root_paths.results is defined
  - item.stat.exists
  - not item.stat.islnk
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-6(a)
  - accounts_root_path_dirs_no_write
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

Group Ensure that Users Have Sensible Umask Values Group contains 3 rules

[ref] The umask setting controls the default permissions for the creation of new files. With a default umask setting of 077, files and directories created by users will not be readable by any other user on the system. Users who wish to make specific files group- or world-readable can accomplish this by using the chmod command. Additionally, users can make all their files readable to their group by default by setting a umask of 027 in their shell configuration files. If default per-user groups exist (that is, if every user has a default group whose name is the same as that user's username and whose only member is the user), then it may even be safe for users to select a umask of 007, making it very easy to intentionally share files with groups of which the user is a member.

Rule Ensure the Default Bash Umask is Set Correctly [ref]

To ensure the default umask for users of the Bash shell is set properly, add or correct the umask setting in /etc/bashrc to read as follows:

umask 027

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_accounts_umask_etc_bashrc

References:

cis-csc	18
cobit5	APO13.01, BAI03.01, BAI03.02, BAI03.03
disa	CCI-000366
isa-62443-2009	4.3.4.3.3
iso27001-2013	A.14.1.1, A.14.2.1, A.14.2.5, A.6.1.5
nerc-cip	CIP-003-8 R5.1.1, CIP-003-8 R5.3, CIP-004-6 R2.3, CIP-007-3 R2.1, CIP-007-3 R2.2, CIP-007-3 R2.3, CIP-007-3 R5.1, CIP-007-3 R5.1.1, CIP-007-3 R5.1.2
nist	AC-6(1), CM-6(a)
nist-csf	PR.IP-2
os-srg	SRG-OS-000480-GPOS-00228, SRG-OS-000480-GPOS-00227
anssi	R36

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - accounts_umask_etc_bashrc
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
- name: XCCDF Value var_accounts_user_umask # promote to variable
  set_fact:
    var_accounts_user_umask: !!str 027
  tags:
    - always

- name: Check if umask in /etc/bashrc is already set
  ansible.builtin.lineinfile:
    path: /etc/bashrc
    regexp: ^[^#]*\bumask\s+\d+$
    state: absent
  check_mode: true
  changed_when: false
  register: umask_replace
  when: '"bash" in ansible_facts.packages'
  tags:
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - accounts_umask_etc_bashrc
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Replace user umask in /etc/bashrc
  ansible.builtin.replace:
    path: /etc/bashrc
    regexp: ^([^#]*\b)umask\s+\d+$
    replace: \g<1>umask {{ var_accounts_user_umask }}
  when:
  - '"bash" in ansible_facts.packages'
  - umask_replace.found > 0
  tags:
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - accounts_umask_etc_bashrc
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Ensure the Default umask is Appended Correctly
  ansible.builtin.lineinfile:
    create: true
    path: /etc/bashrc
    line: umask {{ var_accounts_user_umask }}
  when:
  - '"bash" in ansible_facts.packages'
  - umask_replace.found == 0
  tags:
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - accounts_umask_etc_bashrc
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲

# Remediation is applicable only in certain platforms
if rpm --quiet -q bash; then

var_accounts_user_umask='027'






grep -q "^[^#]*\bumask" /etc/bashrc && \
  sed -i -E -e "s/^([^#]*\bumask)[[:space:]]+[[:digit:]]+/\1 $var_accounts_user_umask/g" /etc/bashrc
if ! [ $? -eq 0 ]; then
    echo "umask $var_accounts_user_umask" >> /etc/bashrc
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Ensure the Default Umask is Set Correctly in login.defs [ref]

To ensure the default umask controlled by /etc/login.defs is set properly, add or correct the UMASK setting in /etc/login.defs to read as follows:

UMASK 027

Rationale:

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_accounts_umask_etc_login_defs

References:

cis-csc	11, 18, 3, 9
cobit5	APO13.01, BAI03.01, BAI03.02, BAI03.03, BAI10.01, BAI10.02, BAI10.03, BAI10.05
disa	CCI-000366
isa-62443-2009	4.3.4.3.2, 4.3.4.3.3
isa-62443-2013	SR 7.6
iso27001-2013	A.12.1.2, A.12.5.1, A.12.6.2, A.14.1.1, A.14.2.1, A.14.2.2, A.14.2.3, A.14.2.4, A.14.2.5, A.6.1.5
nerc-cip	CIP-003-8 R5.1.1, CIP-003-8 R5.3, CIP-004-6 R2.3, CIP-007-3 R2.1, CIP-007-3 R2.2, CIP-007-3 R2.3, CIP-007-3 R5.1, CIP-007-3 R5.1.1, CIP-007-3 R5.1.2
nist	AC-6(1), CM-6(a)
nist-csf	PR.IP-1, PR.IP-2
os-srg	SRG-OS-000480-GPOS-00228
anssi	R36

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - accounts_umask_etc_login_defs
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
- name: XCCDF Value var_accounts_user_umask # promote to variable
  set_fact:
    var_accounts_user_umask: !!str 027
  tags:
    - always

- name: Check if UMASK is already set
  ansible.builtin.lineinfile:
    path: /etc/login.defs
    regexp: ^(\s*)UMASK\s+.*
    state: absent
  check_mode: true
  changed_when: false
  register: result_umask_is_set
  when: '"shadow-utils" in ansible_facts.packages'
  tags:
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - accounts_umask_etc_login_defs
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Replace user UMASK in /etc/login.defs
  ansible.builtin.replace:
    path: /etc/login.defs
    regexp: ^(\s*)UMASK(\s+).*
    replace: \g<1>UMASK\g<2>{{ var_accounts_user_umask }}
  when:
  - '"shadow-utils" in ansible_facts.packages'
  - result_umask_is_set.found > 0
  tags:
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - accounts_umask_etc_login_defs
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Ensure the Default UMASK is Appended Correctly
  ansible.builtin.lineinfile:
    create: true
    path: /etc/login.defs
    line: UMASK {{ var_accounts_user_umask }}
  when:
  - '"shadow-utils" in ansible_facts.packages'
  - result_umask_is_set.found == 0
  tags:
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - accounts_umask_etc_login_defs
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲

# Remediation is applicable only in certain platforms
if rpm --quiet -q shadow-utils; then

var_accounts_user_umask='027'


# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^UMASK")

# shellcheck disable=SC2059
printf -v formatted_output "%s %s" "$stripped_key" "$var_accounts_user_umask"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^UMASK\\>" "/etc/login.defs"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^UMASK\\>.*/$escaped_formatted_output/gi" "/etc/login.defs"
else
    if [[ -s "/etc/login.defs" ]] && [[ -n "$(tail -c 1 -- "/etc/login.defs" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "/etc/login.defs"
    fi
    printf '%s\n' "$formatted_output" >> "/etc/login.defs"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Ensure the Default Umask is Set Correctly in /etc/profile [ref]

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 027

Note 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.

Rationale:

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_accounts_umask_etc_profile

References:

cis-csc	18
cobit5	APO13.01, BAI03.01, BAI03.02, BAI03.03
disa	CCI-000366
isa-62443-2009	4.3.4.3.3
iso27001-2013	A.14.1.1, A.14.2.1, A.14.2.5, A.6.1.5
nerc-cip	CIP-003-8 R5.1.1, CIP-003-8 R5.3, CIP-004-6 R2.3, CIP-007-3 R2.1, CIP-007-3 R2.2, CIP-007-3 R2.3, CIP-007-3 R5.1, CIP-007-3 R5.1.1, CIP-007-3 R5.1.2
nist	AC-6(1), CM-6(a)
nist-csf	PR.IP-2
os-srg	SRG-OS-000480-GPOS-00228, SRG-OS-000480-GPOS-00227
anssi	R36

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: XCCDF Value var_accounts_user_umask # promote to variable
  set_fact:
    var_accounts_user_umask: !!str 027
  tags:
    - always

- name: Ensure the Default Umask is Set Correctly in /etc/profile - Locate Profile
    Configuration Files Where umask Is Defined
  ansible.builtin.find:
    paths:
    - /etc/profile.d
    patterns:
    - sh.local
    - '*.sh'
    contains: ^[\s]*umask\s+\d+
  register: result_profile_d_files
  tags:
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - accounts_umask_etc_profile
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Ensure the Default Umask is Set Correctly in /etc/profile - Replace Existing
    umask Value in Files From /etc/profile.d
  ansible.builtin.replace:
    path: '{{ item.path }}'
    regexp: ^(\s*)umask\s+\d+
    replace: \1umask {{ var_accounts_user_umask }}
  loop: '{{ result_profile_d_files.files }}'
  register: result_umask_replaced_profile_d
  when: result_profile_d_files.matched
  tags:
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - accounts_umask_etc_profile
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Ensure the Default Umask is Set Correctly in /etc/profile - Ensure umask Is
    Set in /etc/profile if Not Already Set Elsewhere
  ansible.builtin.lineinfile:
    create: true
    mode: 420
    path: /etc/profile
    line: umask {{ var_accounts_user_umask }}
  when: not result_profile_d_files.matched
  tags:
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - accounts_umask_etc_profile
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Ensure the Default Umask is Set Correctly in /etc/profile - Ensure umask Value
    For All Existing umask Definition in /etc/profile
  ansible.builtin.replace:
    path: /etc/profile
    regexp: ^(\s*)umask\s+\d+
    replace: \1umask {{ var_accounts_user_umask }}
  register: result_umask_replaced_profile
  tags:
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - accounts_umask_etc_profile
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict


var_accounts_user_umask='027'


readarray -t profile_files < <(find /etc/profile.d/ -type f -name '*.sh' -or -name 'sh.local')

for file in "${profile_files[@]}" /etc/profile; do
  grep -qE '^[^#]*umask' "$file" && sed -i -E "s/^(\s*umask\s*)[0-7]+/\1$var_accounts_user_umask/g" "$file"
done

if ! grep -qrE '^[^#]*umask' /etc/profile*; then
  echo "umask $var_accounts_user_umask" >> /etc/profile
fi

Rule Set Interactive Session Timeout [ref]

Setting the TMOUT option in /etc/profile ensures that all user sessions will terminate based on inactivity. The value of TMOUT should be exported and read only. The TMOUT setting in a file loaded by /etc/profile, e.g. /etc/profile.d/tmout.sh should read as follows:

typeset -xr TMOUT=900

declare -xr TMOUT=900

Using the typeset keyword is preferred for wider compatibility with ksh and other shells.

Rationale:

Terminating an idle session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_accounts_tmout

References:

cis-csc	1, 12, 15, 16
cobit5	DSS05.04, DSS05.10, DSS06.10
cui	3.1.11
disa	CCI-000057, CCI-001133
isa-62443-2009	4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9
isa-62443-2013	SR 1.1, SR 1.10, SR 1.2, SR 1.5, SR 1.7, SR 1.8, SR 1.9
iso27001-2013	A.18.1.4, A.9.2.1, A.9.2.4, A.9.3.1, A.9.4.2, A.9.4.3
nerc-cip	CIP-004-6 R2.2.3, CIP-007-3 R5.1, CIP-007-3 R5.2, CIP-007-3 R5.3.1, CIP-007-3 R5.3.2, CIP-007-3 R5.3.3
nist	AC-12, SC-10, AC-2(5), CM-6(a)
nist-csf	PR.AC-7
os-srg	SRG-OS-000163-GPOS-00072, SRG-OS-000029-GPOS-00010
anssi	R32
pcidss4	8.6.1, 8.6

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.1.11
  - NIST-800-53-AC-12
  - NIST-800-53-AC-2(5)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-SC-10
  - PCI-DSSv4-8.6
  - PCI-DSSv4-8.6.1
  - accounts_tmout
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
- name: XCCDF Value var_accounts_tmout # promote to variable
  set_fact:
    var_accounts_tmout: !!str 900
  tags:
    - always

- name: Correct any occurrence of TMOUT in /etc/profile
  replace:
    path: /etc/profile
    regexp: ^[^#].*TMOUT=.*
    replace: typeset -xr TMOUT={{ var_accounts_tmout }}
  register: profile_replaced
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.11
  - NIST-800-53-AC-12
  - NIST-800-53-AC-2(5)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-SC-10
  - PCI-DSSv4-8.6
  - PCI-DSSv4-8.6.1
  - accounts_tmout
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Set Interactive Session Timeout
  lineinfile:
    path: /etc/profile.d/tmout.sh
    create: true
    regexp: TMOUT=
    line: typeset -xr TMOUT={{ var_accounts_tmout }}
    state: present
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.11
  - NIST-800-53-AC-12
  - NIST-800-53-AC-2(5)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-SC-10
  - PCI-DSSv4-8.6
  - PCI-DSSv4-8.6.1
  - accounts_tmout
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

var_accounts_tmout='900'


# if 0, no occurence of tmout found, if 1, occurence found
tmout_found=0


for f in /etc/profile /etc/profile.d/*.sh; do

    if grep --silent '^[^#].*TMOUT' $f; then
        sed -i -E "s/^(.*)TMOUT\s*=\s*(\w|\$)*(.*)$/typeset -xr TMOUT=$var_accounts_tmout\3/g" $f
        tmout_found=1
    fi
done

if [ $tmout_found -eq 0 ]; then
        echo -e "\n# Set TMOUT to $var_accounts_tmout per security requirements" >> /etc/profile.d/tmout.sh
        echo "typeset -xr TMOUT=$var_accounts_tmout" >> /etc/profile.d/tmout.sh
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule User Initialization Files Must Not Run World-Writable Programs [ref]

Set the mode on files being executed by the user initialization files with the following command:

$ sudo chmod o-w FILE

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_accounts_user_dot_no_world_writable_programs

References:

disa	CCI-000366
os-srg	SRG-OS-000480-GPOS-00227

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: User Initialization Files Must Not Run World-Writable Programs - Initialize
    variables
  set_fact:
    home_user_dirs: []
    world_writable_files: []
  tags:
  - accounts_user_dot_no_world_writable_programs
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: User Initialization Files Must Not Run World-Writable Programs - Get user's
    home dir list
  ansible.builtin.getent:
    database: passwd
  register: passwd_database
  tags:
  - accounts_user_dot_no_world_writable_programs
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: User Initialization Files Must Not Run World-Writable Programs - Fill home_user_dirs
  set_fact:
    home_user_dirs: '{{ home_user_dirs + [item.data[4]] }}'
  when: item.data[4] is defined and item.data[2]|int >= 1000 and item.data[2]|int
    != 65534
  with_items: '{{ passwd_database.ansible_facts.getent_passwd | dict2items(key_name=''user'',
    value_name=''data'')}}'
  tags:
  - accounts_user_dot_no_world_writable_programs
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: User Initialization Files Must Not Run World-Writable Programs - Get world
    writable files
  ansible.builtin.shell: |
    find / -xdev -type f -perm -0002 2> /dev/null
  register: world_writable_files
  tags:
  - accounts_user_dot_no_world_writable_programs
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: User Initialization Files Must Not Run World-Writable Programs - Find referenced_files
    in init files
  ansible.builtin.find:
    paths: '{{ home_user_dirs }}'
    contains: '{{ item }}'
    hidden: true
    read_whole_file: true
    recurse: true
  with_items: '{{ world_writable_files.stdout_lines }}'
  register: referenced_files
  tags:
  - accounts_user_dot_no_world_writable_programs
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: User Initialization Files Must Not Run World-Writable Programs - Remove world
    writable permissions
  ansible.builtin.file:
    path: '{{ item.item }}'
    mode: o-w
  when: item.matched > 0
  with_items: '{{ referenced_files.results }}'
  tags:
  - accounts_user_dot_no_world_writable_programs
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict


readarray -t world_writable_files < <(find / -xdev -type f -perm -0002 2> /dev/null)
readarray -t interactive_home_dirs < <(awk -F':' '{ if ($3 >= 1000 && $3 != 65534) print $6 }' /etc/passwd)

for world_writable in "${world_writable_files[@]}"; do
    for homedir in "${interactive_home_dirs[@]}"; do
        if grep -q -d skip "$world_writable" "$homedir"/.*; then
            chmod o-w $world_writable
            break
        fi
    done
done

Rule All Interactive Users Home Directories Must Exist [ref]

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

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_accounts_user_interactive_home_directory_exists

References:

disa	CCI-000366
os-srg	SRG-OS-000480-GPOS-00227

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Get all local users from /etc/passwd
  ansible.builtin.getent:
    database: passwd
    split: ':'
  tags:
  - accounts_user_interactive_home_directory_exists
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Create local_users variable from the getent output
  ansible.builtin.set_fact:
    local_users: '{{ ansible_facts.getent_passwd|dict2items }}'
  tags:
  - accounts_user_interactive_home_directory_exists
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Ensure interactive users have a home directory exists
  ansible.builtin.user:
    name: '{{ item.key }}'
    create_home: true
  loop: '{{ local_users }}'
  when:
  - item.value[2]|int >= 1000
  - item.value[2]|int != 65534
  tags:
  - accounts_user_interactive_home_directory_exists
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict


for user in $(awk -F':' '{ if ($3 >= 1000 && $3 != 65534) print $1}' /etc/passwd); do
    mkhomedir_helper $user 0077;
done

Rule All Interactive User Home Directories Must Be Group-Owned By The Primary Group [ref]

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/USER

This 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.

Warning: Due to OVAL limitation, this rule can report a false negative in a specific situation where two interactive users swap the group-ownership of their respective home directories.

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_file_groupownership_home_directories

References:

disa	CCI-000366
os-srg	SRG-OS-000480-GPOS-00227

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Get all local users from /etc/passwd
  ansible.builtin.getent:
    database: passwd
    split: ':'
  tags:
  - file_groupownership_home_directories
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Create local_users variable from the getent output
  ansible.builtin.set_fact:
    local_users: '{{ ansible_facts.getent_passwd|dict2items }}'
  tags:
  - file_groupownership_home_directories
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Test for existence of home directories to avoid creating them, but only fixing
    group ownership
  ansible.builtin.stat:
    path: '{{ item.value[4] }}'
  register: path_exists
  loop: '{{ local_users }}'
  when:
  - item.value[1]|int >= 1000
  - item.value[1]|int != 65534
  tags:
  - file_groupownership_home_directories
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Ensure interactive local users are the group-owners of their respective home
    directories
  ansible.builtin.file:
    path: '{{ item.0.value[4] }}'
    group: '{{ item.0.value[2] }}'
  loop: '{{ local_users|zip(path_exists.results)|list }}'
  when: item.1.stat is defined and item.1.stat.exists
  tags:
  - file_groupownership_home_directories
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict


awk -F':' '{ if ($3 >= 1000 && $3 != 65534) system("chgrp -f " $4" "$6) }' /etc/passwd

Rule All Interactive User Home Directories Must Be Owned By The Primary User [ref]

Change the owner of interactive users home directories to that correct owner. To change the owner of a interactive users home directory, use the following command:

$ sudo chown USER /home/USER

This rule ensures every home directory related to an interactive user is owned by an interactive user. It also ensures that interactive users are owners of one and only one home directory.

Warning: Due to OVAL limitation, this rule can report a false negative in a specific situation where two interactive users swap the ownership of their respective home directories.

Rationale:

If a local interactive user does not own their home directory, unauthorized users could access or modify the user's files, and the users may not be able to access their own files.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_file_ownership_home_directories

References:

disa	CCI-000366
os-srg	SRG-OS-000480-GPOS-00227

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Get all local users from /etc/passwd
  ansible.builtin.getent:
    database: passwd
    split: ':'
  tags:
  - file_ownership_home_directories
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Create local_users variable from the getent output
  ansible.builtin.set_fact:
    local_users: '{{ ansible_facts.getent_passwd|dict2items }}'
  tags:
  - file_ownership_home_directories
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Test for existence of home directories to avoid creating them, but only fixing
    ownership
  ansible.builtin.stat:
    path: '{{ item.value[4] }}'
  register: path_exists
  loop: '{{ local_users }}'
  when:
  - item.value[1]|int >= 1000
  - item.value[1]|int != 65534
  tags:
  - file_ownership_home_directories
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Ensure interactive local users are the owners of their respective home directories
  ansible.builtin.file:
    path: '{{ item.0.value[4] }}'
    owner: '{{ item.0.value[1] }}'
  loop: '{{ local_users|zip(path_exists.results)|list }}'
  when: item.1.stat is defined and item.1.stat.exists
  tags:
  - file_ownership_home_directories
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict


awk -F':' '{ if ($3 >= 1000 && $3 != 65534) system("chown -f " $3" "$6) }' /etc/passwd

Rule All Interactive User Home Directories Must Have mode 0750 Or Less Permissive [ref]

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

Rationale:

Excessive permissions on local interactive user home directories may allow unauthorized access to user files by other users.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_file_permissions_home_directories

References:

disa	CCI-000366
os-srg	SRG-OS-000480-GPOS-00227

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Get all local users from /etc/passwd
  ansible.builtin.getent:
    database: passwd
    split: ':'
  tags:
  - file_permissions_home_directories
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Create local_users variable from the getent output
  ansible.builtin.set_fact:
    local_users: '{{ ansible_facts.getent_passwd|dict2items }}'
  tags:
  - file_permissions_home_directories
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Test for existence home directories to avoid creating them.
  ansible.builtin.stat:
    path: '{{ item.value[4] }}'
  register: path_exists
  loop: '{{ local_users }}'
  when:
  - item.value[1]|int >= 1000
  - item.value[1]|int != 65534
  - item.value[4] != "/"
  tags:
  - file_permissions_home_directories
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Ensure interactive local users have proper permissions on their respective
    home directories
  ansible.builtin.file:
    path: '{{ item.0.value[4] }}'
    mode: u-s,g-w-s,o=-
    follow: false
    recurse: false
  loop: '{{ local_users|zip(path_exists.results)|list }}'
  when: item.1.stat is defined and item.1.stat.exists
  tags:
  - file_permissions_home_directories
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict


for home_dir in $(awk -F':' '{ if ($3 >= 1000 && $3 != 65534 && $6 != "/") print $6 }' /etc/passwd); do
    # Only update the permissions when necessary. This will avoid changing the inode timestamp when
    # the permission is already defined as expected, therefore not impacting in possible integrity
    # check systems that also check inodes timestamps.
    find "$home_dir" -maxdepth 0 -perm /7027 \! -type l -exec chmod u-s,g-w-s,o=- {} \;
done

Rule Enable authselect [ref]

Configure user authentication setup to use the authselect tool. If authselect profile is selected, the rule will enable the minimal profile.

Warning: If the sudo authselect select command returns an error informing that the chosen profile cannot be selected, it is probably because PAM files have already been modified by the administrator. If this is the case, in order to not overwrite the desired changes made by the administrator, the current PAM settings should be investigated before forcing the selection of the chosen authselect profile.

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_enable_authselect

References:

disa	CCI-000213
hipaa	164.308(a)(1)(ii)(B), 164.308(a)(7)(i), 164.308(a)(7)(ii)(A), 164.310(a)(1), 164.310(a)(2)(i), 164.310(a)(2)(ii), 164.310(a)(2)(iii), 164.310(b), 164.310(c), 164.310(d)(1), 164.310(d)(2)(iii)
nist	AC-3
ospp	FIA_UAU.1, FIA_AFL.1
os-srg	SRG-OS-000480-GPOS-00227
anssi	R31
pcidss4	8.3.4, 8.3

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	false
Strategy:	configure

- name: XCCDF Value var_authselect_profile # promote to variable
  set_fact:
    var_authselect_profile: !!str minimal
  tags:
    - always

- name: Enable authselect - Check Current authselect Profile
  ansible.builtin.command:
    cmd: authselect current
  register: result_authselect_current
  changed_when: false
  failed_when: false
  tags:
  - NIST-800-53-AC-3
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.4
  - configure_strategy
  - enable_authselect
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed

- name: Enable authselect - Try to Select an authselect Profile
  ansible.builtin.command:
    cmd: authselect select "{{ var_authselect_profile }}"
  register: result_authselect_select
  changed_when: result_authselect_select.rc == 0
  failed_when: false
  when: result_authselect_current.rc != 0
  tags:
  - NIST-800-53-AC-3
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.4
  - configure_strategy
  - enable_authselect
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed

- name: Enable authselect - Verify If pam Has Been Altered
  ansible.builtin.command:
    cmd: rpm -qV pam
  register: result_altered_authselect
  changed_when: false
  failed_when: false
  when:
  - result_authselect_select is not skipped
  - result_authselect_select.rc != 0
  tags:
  - NIST-800-53-AC-3
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.4
  - configure_strategy
  - enable_authselect
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed

- name: Enable authselect - Informative Message Based on authselect Integrity Check
  ansible.builtin.assert:
    that:
    - result_authselect_current.rc == 0 or result_altered_authselect is skipped or
      result_altered_authselect.rc == 0
    fail_msg:
    - authselect is not used but files from the 'pam' package have been altered, so
      the authselect configuration won't be forced.
  tags:
  - NIST-800-53-AC-3
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.4
  - configure_strategy
  - enable_authselect
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed

- name: Enable authselect - Force authselect Profile Selection
  ansible.builtin.command:
    cmd: authselect select --force "{{ var_authselect_profile }}"
  when:
  - result_authselect_current.rc != 0
  - result_authselect_select.rc != 0
  - result_altered_authselect.rc == 0
  tags:
  - NIST-800-53-AC-3
  - PCI-DSSv4-8.3
  - PCI-DSSv4-8.3.4
  - configure_strategy
  - enable_authselect
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed

Remediation Shell script ⇲


var_authselect_profile='minimal'


authselect current

if test "$?" -ne 0; then
    authselect select "$var_authselect_profile"

    if test "$?" -ne 0; then
        if rpm --quiet --verify pam; then
            authselect select --force "$var_authselect_profile"
        else
	        echo "authselect is not used but files from the 'pam' package have been altered, so the authselect configuration won't be forced." >&2
        fi
    fi
fi

Group GRUB2 bootloader configuration Group contains 2 groups and 14 rules

[ref] During the boot process, the boot loader is responsible for starting the execution of the kernel and passing options to it. The boot loader allows for the selection of different kernels - possibly on different partitions or media. The default Fedora boot loader for x86 systems is called GRUB2. Options it can pass to the kernel include single-user mode, which provides root access without any authentication, and the ability to disable SELinux. To prevent local users from modifying the boot parameters and endangering security, protect the boot loader configuration with a password and ensure its configuration file's permissions are set properly.

Group Non-UEFI GRUB2 bootloader configuration Group contains 7 rules

[ref] Non-UEFI GRUB2 bootloader configuration

Rule Verify /boot/grub2/grub.cfg Group Ownership [ref]

The file /boot/grub2/grub.cfg should be group-owned by the root group to prevent destruction or modification of the file. To properly set the group owner of /boot/grub2/grub.cfg, run the command:

$ sudo chgrp root /boot/grub2/grub.cfg

Rationale:

The root group is a highly-privileged group. Furthermore, the group-owner of this file should not have any access privileges anyway.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_file_groupowner_grub2_cfg

References:

cis-csc	12, 13, 14, 15, 16, 18, 3, 5
cjis	5.5.2.2
cobit5	APO01.06, DSS05.04, DSS05.07, DSS06.02
cui	3.4.5
disa	CCI-000366
hipaa	164.308(a)(1)(ii)(B), 164.308(a)(7)(i), 164.308(a)(7)(ii)(A), 164.310(a)(1), 164.310(a)(2)(i), 164.310(a)(2)(ii), 164.310(a)(2)(iii), 164.310(b), 164.310(c), 164.310(d)(1), 164.310(d)(2)(iii)
isa-62443-2009	4.3.3.7.3
isa-62443-2013	SR 2.1, SR 5.2
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-6(a), AC-6(1)
nist-csf	PR.AC-4, PR.DS-5
pcidss	Req-7.1
os-srg	SRG-OS-000480-GPOS-00227
anssi	R29
pcidss4	2.2.6, 2.2

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_groupowner_grub2_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Test for existence /boot/grub2/grub.cfg
  stat:
    path: /boot/grub2/grub.cfg
  register: file_exists
  when:
  - '"/boot/efi" not in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_groupowner_grub2_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure group owner 0 on /boot/grub2/grub.cfg
  file:
    path: /boot/grub2/grub.cfg
    group: '0'
  when:
  - '"/boot/efi" not in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - file_exists.stat is defined and file_exists.stat.exists
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_groupowner_grub2_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

# Remediation is applicable only in certain platforms
if [ ! -d /sys/firmware/efi ] && rpm --quiet -q grub2-common && { [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; }; then

chgrp 0 /boot/grub2/grub.cfg

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Verify /boot/grub2/user.cfg Group Ownership [ref]

The file /boot/grub2/user.cfg should be group-owned by the root group to prevent reading or modification of the file. To properly set the group owner of /boot/grub2/user.cfg, run the command:

$ sudo chgrp root /boot/grub2/user.cfg

Rationale:

The root group is a highly-privileged group. Furthermore, the group-owner of this file should not have any access privileges anyway. Non-root users who read the boot parameters may be able to identify weaknesses in security upon boot and be able to exploit them.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_file_groupowner_user_cfg

References:

cis-csc	12, 13, 14, 15, 16, 18, 3, 5
cjis	5.5.2.2
cobit5	APO01.06, DSS05.04, DSS05.07, DSS06.02
cui	3.4.5
disa	CCI-000225
hipaa	164.308(a)(1)(ii)(B), 164.308(a)(7)(i), 164.308(a)(7)(ii)(A), 164.310(a)(1), 164.310(a)(2)(i), 164.310(a)(2)(ii), 164.310(a)(2)(iii), 164.310(b), 164.310(c), 164.310(d)(1), 164.310(d)(2)(iii)
isa-62443-2009	4.3.3.7.3
isa-62443-2013	SR 2.1, SR 5.2
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-6(a), AC-6(1)
nist-csf	PR.AC-4, PR.DS-5
pcidss	Req-7.1
os-srg	SRG-OS-000480-GPOS-00227
anssi	R29
pcidss4	2.2.6, 2.2

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_groupowner_user_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Test for existence /boot/grub2/user.cfg
  stat:
    path: /boot/grub2/user.cfg
  register: file_exists
  when:
  - '"/boot/efi" not in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_groupowner_user_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure group owner 0 on /boot/grub2/user.cfg
  file:
    path: /boot/grub2/user.cfg
    group: '0'
  when:
  - '"/boot/efi" not in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - file_exists.stat is defined and file_exists.stat.exists
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_groupowner_user_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

# Remediation is applicable only in certain platforms
if [ ! -d /sys/firmware/efi ] && rpm --quiet -q grub2-common && { [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; }; then

chgrp 0 /boot/grub2/user.cfg

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Verify /boot/grub2/grub.cfg User Ownership [ref]

The file /boot/grub2/grub.cfg should be owned by the root user to prevent destruction or modification of the file. To properly set the owner of /boot/grub2/grub.cfg, run the command:

$ sudo chown root /boot/grub2/grub.cfg

Rationale:

Only root should be able to modify important boot parameters.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_file_owner_grub2_cfg

References:

cis-csc	12, 13, 14, 15, 16, 18, 3, 5
cjis	5.5.2.2
cobit5	APO01.06, DSS05.04, DSS05.07, DSS06.02
cui	3.4.5
disa	CCI-000366
hipaa	164.308(a)(1)(ii)(B), 164.308(a)(7)(i), 164.308(a)(7)(ii)(A), 164.310(a)(1), 164.310(a)(2)(i), 164.310(a)(2)(ii), 164.310(a)(2)(iii), 164.310(b), 164.310(c), 164.310(d)(1), 164.310(d)(2)(iii)
isa-62443-2009	4.3.3.7.3
isa-62443-2013	SR 2.1, SR 5.2
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-6(a), AC-6(1)
nist-csf	PR.AC-4, PR.DS-5
pcidss	Req-7.1
os-srg	SRG-OS-000480-GPOS-00227
anssi	R29
pcidss4	2.2.6, 2.2

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_owner_grub2_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Test for existence /boot/grub2/grub.cfg
  stat:
    path: /boot/grub2/grub.cfg
  register: file_exists
  when:
  - '"/boot/efi" not in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_owner_grub2_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure owner 0 on /boot/grub2/grub.cfg
  file:
    path: /boot/grub2/grub.cfg
    owner: '0'
  when:
  - '"/boot/efi" not in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - file_exists.stat is defined and file_exists.stat.exists
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_owner_grub2_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

# Remediation is applicable only in certain platforms
if [ ! -d /sys/firmware/efi ] && rpm --quiet -q grub2-common && { [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; }; then

chown 0 /boot/grub2/grub.cfg

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Verify /boot/grub2/user.cfg User Ownership [ref]

The file /boot/grub2/user.cfg should be owned by the root user to prevent reading or modification of the file. To properly set the owner of /boot/grub2/user.cfg, run the command:

$ sudo chown root /boot/grub2/user.cfg

Rationale:

Only root should be able to modify important boot parameters. Also, non-root users who read the boot parameters may be able to identify weaknesses in security upon boot and be able to exploit them.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_file_owner_user_cfg

References:

cis-csc	12, 13, 14, 15, 16, 18, 3, 5
cjis	5.5.2.2
cobit5	APO01.06, DSS05.04, DSS05.07, DSS06.02
cui	3.4.5
disa	CCI-000225
hipaa	164.308(a)(1)(ii)(B), 164.308(a)(7)(i), 164.308(a)(7)(ii)(A), 164.310(a)(1), 164.310(a)(2)(i), 164.310(a)(2)(ii), 164.310(a)(2)(iii), 164.310(b), 164.310(c), 164.310(d)(1), 164.310(d)(2)(iii)
isa-62443-2009	4.3.3.7.3
isa-62443-2013	SR 2.1, SR 5.2
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-6(a), AC-6(1)
nist-csf	PR.AC-4, PR.DS-5
pcidss	Req-7.1
anssi	R29
pcidss4	2.2.6, 2.2

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_owner_user_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Test for existence /boot/grub2/user.cfg
  stat:
    path: /boot/grub2/user.cfg
  register: file_exists
  when:
  - '"/boot/efi" not in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_owner_user_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure owner 0 on /boot/grub2/user.cfg
  file:
    path: /boot/grub2/user.cfg
    owner: '0'
  when:
  - '"/boot/efi" not in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - file_exists.stat is defined and file_exists.stat.exists
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_owner_user_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

# Remediation is applicable only in certain platforms
if [ ! -d /sys/firmware/efi ] && rpm --quiet -q grub2-common && { [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; }; then

chown 0 /boot/grub2/user.cfg

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Verify /boot/grub2/grub.cfg Permissions [ref]

File permissions for /boot/grub2/grub.cfg should be set to 600. To properly set the permissions of /boot/grub2/grub.cfg, run the command:

$ sudo chmod 600 /boot/grub2/grub.cfg

Rationale:

Proper permissions ensure that only the root user can modify important boot parameters.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_file_permissions_grub2_cfg

References:

cis-csc	12, 13, 14, 15, 16, 18, 3, 5
cobit5	APO01.06, DSS05.04, DSS05.07, DSS06.02
cui	3.4.5
disa	CCI-000225
hipaa	164.308(a)(1)(ii)(B), 164.308(a)(7)(i), 164.308(a)(7)(ii)(A), 164.310(a)(1), 164.310(a)(2)(i), 164.310(a)(2)(ii), 164.310(a)(2)(iii), 164.310(b), 164.310(c), 164.310(d)(1), 164.310(d)(2)(iii)
isa-62443-2009	4.3.3.7.3
isa-62443-2013	SR 2.1, SR 5.2
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-6(a), AC-6(1)
nist-csf	PR.AC-4, PR.DS-5
anssi	R29
pcidss4	2.2.6, 2.2

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_permissions_grub2_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Test for existence /boot/grub2/grub.cfg
  stat:
    path: /boot/grub2/grub.cfg
  register: file_exists
  when:
  - '"/boot/efi" not in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_permissions_grub2_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure permission u-xs,g-xwrs,o-xwrt on /boot/grub2/grub.cfg
  file:
    path: /boot/grub2/grub.cfg
    mode: u-xs,g-xwrs,o-xwrt
  when:
  - '"/boot/efi" not in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - file_exists.stat is defined and file_exists.stat.exists
  tags:
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_permissions_grub2_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

# Remediation is applicable only in certain platforms
if [ ! -d /sys/firmware/efi ] && rpm --quiet -q grub2-common && { [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; }; then

chmod u-xs,g-xwrs,o-xwrt /boot/grub2/grub.cfg

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Verify /boot/grub2/user.cfg Permissions [ref]

File permissions for /boot/grub2/user.cfg should be set to 600. To properly set the permissions of /boot/grub2/user.cfg, run the command:

$ sudo chmod 600 /boot/grub2/user.cfg

Rationale:

Proper permissions ensure that only the root user can read or modify important boot parameters.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_file_permissions_user_cfg

References:

cis-csc	12, 13, 14, 15, 16, 18, 3, 5
cobit5	APO01.06, DSS05.04, DSS05.07, DSS06.02
cui	3.4.5
disa	CCI-000225
hipaa	164.308(a)(1)(ii)(B), 164.308(a)(7)(i), 164.308(a)(7)(ii)(A), 164.310(a)(1), 164.310(a)(2)(i), 164.310(a)(2)(ii), 164.310(a)(2)(iii), 164.310(b), 164.310(c), 164.310(d)(1), 164.310(d)(2)(iii)
isa-62443-2009	4.3.3.7.3
isa-62443-2013	SR 2.1, SR 5.2
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-6(a), AC-6(1)
nist-csf	PR.AC-4, PR.DS-5
anssi	R29
pcidss4	2.2.6, 2.2

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_permissions_user_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Test for existence /boot/grub2/user.cfg
  stat:
    path: /boot/grub2/user.cfg
  register: file_exists
  when:
  - '"/boot/efi" not in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_permissions_user_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure permission u-xs,g-xwrs,o-xwrt on /boot/grub2/user.cfg
  file:
    path: /boot/grub2/user.cfg
    mode: u-xs,g-xwrs,o-xwrt
  when:
  - '"/boot/efi" not in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - file_exists.stat is defined and file_exists.stat.exists
  tags:
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSSv4-2.2
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_permissions_user_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

# Remediation is applicable only in certain platforms
if [ ! -d /sys/firmware/efi ] && rpm --quiet -q grub2-common && { [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; }; then

chmod u-xs,g-xwrs,o-xwrt /boot/grub2/user.cfg

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Set Boot Loader Password in grub2 [ref]

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-setpassword

When prompted, enter the password that was selected.

Warning: To prevent hard-coded passwords, automatic remediation of this control is not available. Remediation must be automated as a component of machine provisioning, or followed manually as outlined above. Also, do NOT manually add the superuser account and password to the grub.cfg file as the grub2-mkconfig command overwrites this file.

Rationale:

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.

Severity:

high

Rule ID: xccdf_org.ssgproject.content_rule_grub2_password

References:

cis-csc	1, 11, 12, 14, 15, 16, 18, 3, 5
cobit5	DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.03, DSS06.06, DSS06.10
cui	3.4.5
disa	CCI-000213
hipaa	164.308(a)(1)(ii)(B), 164.308(a)(7)(i), 164.308(a)(7)(ii)(A), 164.310(a)(1), 164.310(a)(2)(i), 164.310(a)(2)(ii), 164.310(a)(2)(iii), 164.310(b), 164.310(c), 164.310(d)(1), 164.310(d)(2)(iii)
isa-62443-2009	4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4
isa-62443-2013	SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7
iso27001-2013	A.18.1.4, A.6.1.2, A.7.1.1, A.9.1.2, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.1, A.9.4.2, A.9.4.3, A.9.4.4, A.9.4.5
nist	CM-6(a)
nist-csf	PR.AC-1, PR.AC-4, PR.AC-6, PR.AC-7, PR.PT-3
os-srg	SRG-OS-000080-GPOS-00048
anssi	R5

Group UEFI GRUB2 bootloader configuration Group contains 7 rules

[ref] UEFI GRUB2 bootloader configuration

Warning: UEFI generally uses vfat file systems, which does not support Unix-style permissions managed by chmod command. In this case, in order to change file permissions for files within /boot/efi it is necessary to update the mount options in /etc/fstab file and reboot the system.

Rule Verify the UEFI Boot Loader grub.cfg Group Ownership [ref]

$ sudo chgrp root /boot/grub2/grub.cfg

Rationale:

The root group is a highly-privileged group. Furthermore, the group-owner of this file should not have any access privileges anyway.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_file_groupowner_efi_grub2_cfg

References:

cis-csc	12, 13, 14, 15, 16, 18, 3, 5
cjis	5.5.2.2
cobit5	APO01.06, DSS05.04, DSS05.07, DSS06.02
cui	3.4.5
disa	CCI-000225
isa-62443-2009	4.3.3.7.3
isa-62443-2013	SR 2.1, SR 5.2
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-6(a), AC-6(1)
nist-csf	PR.AC-4, PR.DS-5
pcidss	Req-7.1
anssi	R29

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - configure_strategy
  - file_groupowner_efi_grub2_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Test for existence /boot/grub2/grub.cfg
  stat:
    path: /boot/grub2/grub.cfg
  register: file_exists
  when:
  - '"/boot/efi" in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - configure_strategy
  - file_groupowner_efi_grub2_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure group owner 0 on /boot/grub2/grub.cfg
  file:
    path: /boot/grub2/grub.cfg
    group: '0'
  when:
  - '"/boot/efi" in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - file_exists.stat is defined and file_exists.stat.exists
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - configure_strategy
  - file_groupowner_efi_grub2_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

# Remediation is applicable only in certain platforms
if [ -d /sys/firmware/efi ] && rpm --quiet -q grub2-common && { [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; }; then

chgrp 0 /boot/grub2/grub.cfg

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Verify /boot/grub2/user.cfg Group Ownership [ref]

The file /boot/grub2/user.cfg should be group-owned by the root group to prevent reading or modification of the file. To properly set the group owner of /boot/grub2/user.cfg, run the command:

$ sudo chgrp root /boot/grub2/user.cfg

Rationale:

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_file_groupowner_efi_user_cfg

References:

cis-csc	12, 13, 14, 15, 16, 18, 3, 5
cjis	5.5.2.2
cobit5	APO01.06, DSS05.04, DSS05.07, DSS06.02
cui	3.4.5
disa	CCI-000225
isa-62443-2009	4.3.3.7.3
isa-62443-2013	SR 2.1, SR 5.2
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-6(a), AC-6(1)
nist-csf	PR.AC-4, PR.DS-5
pcidss	Req-7.1
anssi	R29

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - configure_strategy
  - file_groupowner_efi_user_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Test for existence /boot/grub2/user.cfg
  stat:
    path: /boot/grub2/user.cfg
  register: file_exists
  when:
  - '"/boot/efi" in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - configure_strategy
  - file_groupowner_efi_user_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure group owner 0 on /boot/grub2/user.cfg
  file:
    path: /boot/grub2/user.cfg
    group: '0'
  when:
  - '"/boot/efi" in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - file_exists.stat is defined and file_exists.stat.exists
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - configure_strategy
  - file_groupowner_efi_user_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

# Remediation is applicable only in certain platforms
if [ -d /sys/firmware/efi ] && rpm --quiet -q grub2-common && { [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; }; then

chgrp 0 /boot/grub2/user.cfg

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Verify the UEFI Boot Loader grub.cfg User Ownership [ref]

The file /boot/grub2/grub.cfg should be owned by the root user to prevent destruction or modification of the file. To properly set the owner of /boot/grub2/grub.cfg, run the command:

$ sudo chown root /boot/grub2/grub.cfg

Rationale:

Only root should be able to modify important boot parameters.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_file_owner_efi_grub2_cfg

References:

cis-csc	12, 13, 14, 15, 16, 18, 3, 5
cjis	5.5.2.2
cobit5	APO01.06, DSS05.04, DSS05.07, DSS06.02
cui	3.4.5
disa	CCI-000225
isa-62443-2009	4.3.3.7.3
isa-62443-2013	SR 2.1, SR 5.2
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-6(a), AC-6(1)
nist-csf	PR.AC-4, PR.DS-5
pcidss	Req-7.1
anssi	R29

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - configure_strategy
  - file_owner_efi_grub2_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Test for existence /boot/grub2/grub.cfg
  stat:
    path: /boot/grub2/grub.cfg
  register: file_exists
  when:
  - '"/boot/efi" in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - configure_strategy
  - file_owner_efi_grub2_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure owner 0 on /boot/grub2/grub.cfg
  file:
    path: /boot/grub2/grub.cfg
    owner: '0'
  when:
  - '"/boot/efi" in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - file_exists.stat is defined and file_exists.stat.exists
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - configure_strategy
  - file_owner_efi_grub2_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

# Remediation is applicable only in certain platforms
if [ -d /sys/firmware/efi ] && rpm --quiet -q grub2-common && { [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; }; then

chown 0 /boot/grub2/grub.cfg

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Verify /boot/grub2/user.cfg User Ownership [ref]

The file /boot/grub2/user.cfg should be owned by the root user to prevent reading or modification of the file. To properly set the owner of /boot/grub2/user.cfg, run the command:

$ sudo chown root /boot/grub2/user.cfg

Rationale:

Only root should be able to modify important boot parameters. Also, non-root users who read the boot parameters may be able to identify weaknesses in security upon boot and be able to exploit them.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_file_owner_efi_user_cfg

References:

cis-csc	12, 13, 14, 15, 16, 18, 3, 5
cjis	5.5.2.2
cobit5	APO01.06, DSS05.04, DSS05.07, DSS06.02
cui	3.4.5
disa	CCI-000225
isa-62443-2009	4.3.3.7.3
isa-62443-2013	SR 2.1, SR 5.2
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-6(a), AC-6(1)
nist-csf	PR.AC-4, PR.DS-5
pcidss	Req-7.1
anssi	R29

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - configure_strategy
  - file_owner_efi_user_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Test for existence /boot/grub2/user.cfg
  stat:
    path: /boot/grub2/user.cfg
  register: file_exists
  when:
  - '"/boot/efi" in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - configure_strategy
  - file_owner_efi_user_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure owner 0 on /boot/grub2/user.cfg
  file:
    path: /boot/grub2/user.cfg
    owner: '0'
  when:
  - '"/boot/efi" in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - file_exists.stat is defined and file_exists.stat.exists
  tags:
  - CJIS-5.5.2.2
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-7.1
  - configure_strategy
  - file_owner_efi_user_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

# Remediation is applicable only in certain platforms
if [ -d /sys/firmware/efi ] && rpm --quiet -q grub2-common && { [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; }; then

chown 0 /boot/grub2/user.cfg

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Verify the UEFI Boot Loader grub.cfg Permissions [ref]

File permissions for /boot/grub2/grub.cfg should be set to 700. To properly set the permissions of /boot/grub2/grub.cfg, run the command:

$ sudo chmod 700 /boot/grub2/grub.cfg

Rationale:

Proper permissions ensure that only the root user can modify important boot parameters.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_file_permissions_efi_grub2_cfg

References:

cis-csc	12, 13, 14, 15, 16, 18, 3, 5
cobit5	APO01.06, DSS05.04, DSS05.07, DSS06.02
cui	3.4.5
disa	CCI-000225
isa-62443-2009	4.3.3.7.3
isa-62443-2013	SR 2.1, SR 5.2
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-6(a), AC-6(1)
nist-csf	PR.AC-4, PR.DS-5
anssi	R29

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - configure_strategy
  - file_permissions_efi_grub2_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Test for existence /boot/grub2/grub.cfg
  stat:
    path: /boot/grub2/grub.cfg
  register: file_exists
  when:
  - '"/boot/efi" in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - configure_strategy
  - file_permissions_efi_grub2_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure permission u-s,g-xwrs,o-xwrt on /boot/grub2/grub.cfg
  file:
    path: /boot/grub2/grub.cfg
    mode: u-s,g-xwrs,o-xwrt
  when:
  - '"/boot/efi" in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - file_exists.stat is defined and file_exists.stat.exists
  tags:
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - configure_strategy
  - file_permissions_efi_grub2_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

# Remediation is applicable only in certain platforms
if [ -d /sys/firmware/efi ] && rpm --quiet -q grub2-common && { [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; }; then

chmod u-s,g-xwrs,o-xwrt /boot/grub2/grub.cfg

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Verify /boot/grub2/user.cfg Permissions [ref]

File permissions for /boot/grub2/user.cfg should be set to 600. To properly set the permissions of /boot/grub2/user.cfg, run the command:

$ sudo chmod 600 /boot/grub2/user.cfg

Rationale:

Proper permissions ensure that only the root user can read or modify important boot parameters.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_file_permissions_efi_user_cfg

References:

cis-csc	12, 13, 14, 15, 16, 18, 3, 5
cobit5	APO01.06, DSS05.04, DSS05.07, DSS06.02
cui	3.4.5
disa	CCI-000225
isa-62443-2009	4.3.3.7.3
isa-62443-2013	SR 2.1, SR 5.2
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-6(a), AC-6(1)
nist-csf	PR.AC-4, PR.DS-5
anssi	R29

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - configure_strategy
  - file_permissions_efi_user_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Test for existence /boot/grub2/user.cfg
  stat:
    path: /boot/grub2/user.cfg
  register: file_exists
  when:
  - '"/boot/efi" in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - configure_strategy
  - file_permissions_efi_user_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure permission u-s,g-xwrs,o-xwrt on /boot/grub2/user.cfg
  file:
    path: /boot/grub2/user.cfg
    mode: u-s,g-xwrs,o-xwrt
  when:
  - '"/boot/efi" in ansible_mounts | map(attribute="mount") | list'
  - '"grub2-common" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - file_exists.stat is defined and file_exists.stat.exists
  tags:
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - configure_strategy
  - file_permissions_efi_user_cfg
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	configure

# Remediation is applicable only in certain platforms
if [ -d /sys/firmware/efi ] && rpm --quiet -q grub2-common && { [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; }; then

chmod u-s,g-xwrs,o-xwrt /boot/grub2/user.cfg

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Set the UEFI Boot Loader Password [ref]

# grub2-setpassword

When prompted, enter the password that was selected.

Rationale:

Severity:

high

Rule ID: xccdf_org.ssgproject.content_rule_grub2_uefi_password

References:

cis-csc	11, 12, 14, 15, 16, 18, 3, 5
cobit5	DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS06.03, DSS06.06
cui	3.4.5
disa	CCI-000213
hipaa	164.308(a)(1)(ii)(B), 164.308(a)(7)(i), 164.308(a)(7)(ii)(A), 164.310(a)(1), 164.310(a)(2)(i), 164.310(a)(2)(ii), 164.310(a)(2)(iii), 164.310(b), 164.310(c), 164.310(d)(1), 164.310(d)(2)(iii)
isa-62443-2009	4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4
isa-62443-2013	SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7
iso27001-2013	A.6.1.2, A.7.1.1, A.9.1.2, A.9.2.1, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-6(a)
nist-csf	PR.AC-4, PR.AC-6, PR.PT-3
ospp	FIA_UAU.1
os-srg	SRG-OS-000080-GPOS-00048
anssi	R5

Group Configure Syslog Group contains 1 group and 4 rules

[ref] The syslog service has been the default Unix logging mechanism for many years. It has a number of downsides, including inconsistent log format, lack of authentication for received messages, and lack of authentication, encryption, or reliable transport for messages sent over a network. However, due to its long history, syslog is a de facto standard which is supported by almost all Unix applications.

In Fedora, rsyslog has replaced ksyslogd as the syslog daemon of choice, and it includes some additional security features such as reliable, connection-oriented (i.e. TCP) transmission of logs, the option to log to database formats, and the encryption of log data en route to a central logging server. This section discusses how to configure rsyslog for best effect, and how to use tools provided with the system to maintain and monitor logs.

Group systemd-journald Group contains 4 rules

[ref] systemd-journald is a system service that collects and stores logging data. It creates and maintains structured, indexed journals based on logging information that is received from a variety of sources. For more information on systemd-journald and additional systemd-journald configuration options, see https://systemd.io/.

Rule Enable systemd-journald Service [ref]

The systemd-journald service is an essential component of systemd. The systemd-journald service can be enabled with the following command:

$ sudo systemctl enable systemd-journald.service

Rationale:

In the event of a system failure, Fedora must preserve any information necessary to determine cause of failure and any information necessary to return to operations with least disruption to system processes.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_service_systemd-journald_enabled

References:

disa	CCI-001665
nist	SC-24
os-srg	SRG-OS-000269-GPOS-00103

Remediation Puppet snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable

include enable_systemd-journald

class enable_systemd-journald {
  service {'systemd-journald':
    enable => true,
    ensure => 'running',
  }
}

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-53-SC-24
  - enable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_systemd-journald_enabled

- name: Enable systemd-journald Service - Enable service systemd-journald
  block:

  - name: Gather the package facts
    package_facts:
      manager: auto

  - name: Enable systemd-journald Service - Enable Service systemd-journald
    ansible.builtin.systemd:
      name: systemd-journald
      enabled: true
      state: started
      masked: false
    when:
    - '"systemd" in ansible_facts.packages'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-53-SC-24
  - enable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_systemd-journald_enabled

Remediation script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	disable


service enable systemd-journald

Remediation OSBuild Blueprint snippet ⇲


[customizations.services]
enabled = ["systemd-journald"]

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

SYSTEMCTL_EXEC='/usr/bin/systemctl'
"$SYSTEMCTL_EXEC" unmask 'systemd-journald.service'
"$SYSTEMCTL_EXEC" start 'systemd-journald.service'
"$SYSTEMCTL_EXEC" enable 'systemd-journald.service'

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Ensure journald is configured to compress large log files [ref]

The journald system can compress large log files to avoid fill the system disk.

Rationale:

Log files that are not properly compressed run the risk of growing so large that they fill up the log partition. Valuable logging information could be lost if the log partition becomes full.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_journald_compress

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - journald_compress
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Ensure journald is configured to compress large log files - Search for a section
    in files
  ansible.builtin.find:
    paths: '{{item.path}}'
    patterns: '{{item.pattern}}'
    contains: ^\s*\[Journal\]
    read_whole_file: true
    use_regex: true
  register: systemd_dropin_files_with_section
  loop:
  - path: '{{ ''/etc/systemd/journald.conf'' | dirname }}'
    pattern: '{{ ''/etc/systemd/journald.conf'' | basename | regex_escape }}'
  - path: /etc/systemd/journald.conf.d
    pattern: .*\.conf
  when: '"kernel" in ansible_facts.packages'
  tags:
  - journald_compress
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Ensure journald is configured to compress large log files - Count number of
    files which contain the correct section
  ansible.builtin.set_fact:
    count_of_systemd_dropin_files_with_section: '{{systemd_dropin_files_with_section.results
      | map(attribute=''matched'') | list | map(''int'') | sum}}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - journald_compress
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Ensure journald is configured to compress large log files - Add missing configuration
    to correct section
  ini_file:
    path: '{{item}}'
    section: Journal
    option: Compress
    value: 'yes'
    state: present
    no_extra_spaces: true
  when:
  - '"kernel" in ansible_facts.packages'
  - count_of_systemd_dropin_files_with_section | int > 0
  loop: '{{systemd_dropin_files_with_section.results | sum(attribute=''files'', start=[])
    | map(attribute=''path'') | list }}'
  tags:
  - journald_compress
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Ensure journald is configured to compress large log files - Add configuration
    to new remediation file
  ini_file:
    path: /etc/systemd/journald.conf.d/complianceascode_hardening.conf
    section: Journal
    option: Compress
    value: 'yes'
    state: present
    no_extra_spaces: true
    create: true
  when:
  - '"kernel" in ansible_facts.packages'
  - count_of_systemd_dropin_files_with_section | int == 0
  tags:
  - journald_compress
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

found=false

# set value in all files if they contain section or key
for f in $(echo -n "/etc/systemd/journald.conf.d/complianceascode_hardening.conf /etc/systemd/journald.conf.d/*.conf /etc/systemd/journald.conf"); do
    if [ ! -e "$f" ]; then
        continue
    fi

    # find key in section and change value
    if grep -qzosP "[[:space:]]*\[Journal\]([^\n\[]*\n+)+?[[:space:]]*Compress" "$f"; then

            sed -i "s/Compress[^(\n)]*/Compress=yes/" "$f"

            found=true

    # find section and add key = value to it
    elif grep -qs "[[:space:]]*\[Journal\]" "$f"; then

            sed -i "/[[:space:]]*\[Journal\]/a Compress=yes" "$f"

            found=true
    fi
done

# if section not in any file, append section with key = value to FIRST file in files parameter
if ! $found ; then
    file=$(echo "/etc/systemd/journald.conf.d/complianceascode_hardening.conf /etc/systemd/journald.conf.d/*.conf /etc/systemd/journald.conf" | cut -f1 -d ' ')
    mkdir -p "$(dirname "$file")"

    echo -e "[Journal]\nCompress=yes" >> "$file"

fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Ensure journald is configured to write log files to persistent disk [ref]

The journald system may store log files in volatile memory or locally on disk. If the logs are only stored in volatile memory they will we lost upon reboot.

Rationale:

Log files contain valuable data and need to be persistent to aid in possible investigations.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_journald_storage

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - journald_storage
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Ensure journald is configured to write log files to persistent disk - Search
    for a section in files
  ansible.builtin.find:
    paths: '{{item.path}}'
    patterns: '{{item.pattern}}'
    contains: ^\s*\[Journal\]
    read_whole_file: true
    use_regex: true
  register: systemd_dropin_files_with_section
  loop:
  - path: '{{ ''/etc/systemd/journald.conf'' | dirname }}'
    pattern: '{{ ''/etc/systemd/journald.conf'' | basename | regex_escape }}'
  - path: /etc/systemd/journald.conf.d
    pattern: .*\.conf
  when: '"kernel" in ansible_facts.packages'
  tags:
  - journald_storage
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Ensure journald is configured to write log files to persistent disk - Count
    number of files which contain the correct section
  ansible.builtin.set_fact:
    count_of_systemd_dropin_files_with_section: '{{systemd_dropin_files_with_section.results
      | map(attribute=''matched'') | list | map(''int'') | sum}}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - journald_storage
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Ensure journald is configured to write log files to persistent disk - Add
    missing configuration to correct section
  ini_file:
    path: '{{item}}'
    section: Journal
    option: Storage
    value: persistent
    state: present
    no_extra_spaces: true
  when:
  - '"kernel" in ansible_facts.packages'
  - count_of_systemd_dropin_files_with_section | int > 0
  loop: '{{systemd_dropin_files_with_section.results | sum(attribute=''files'', start=[])
    | map(attribute=''path'') | list }}'
  tags:
  - journald_storage
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Ensure journald is configured to write log files to persistent disk - Add
    configuration to new remediation file
  ini_file:
    path: /etc/systemd/journald.conf.d/complianceascode_hardening.conf
    section: Journal
    option: Storage
    value: persistent
    state: present
    no_extra_spaces: true
    create: true
  when:
  - '"kernel" in ansible_facts.packages'
  - count_of_systemd_dropin_files_with_section | int == 0
  tags:
  - journald_storage
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	restrict

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

found=false

# set value in all files if they contain section or key
for f in $(echo -n "/etc/systemd/journald.conf.d/complianceascode_hardening.conf /etc/systemd/journald.conf.d/*.conf /etc/systemd/journald.conf"); do
    if [ ! -e "$f" ]; then
        continue
    fi

    # find key in section and change value
    if grep -qzosP "[[:space:]]*\[Journal\]([^\n\[]*\n+)+?[[:space:]]*Storage" "$f"; then

            sed -i "s/Storage[^(\n)]*/Storage=persistent/" "$f"

            found=true

    # find section and add key = value to it
    elif grep -qs "[[:space:]]*\[Journal\]" "$f"; then

            sed -i "/[[:space:]]*\[Journal\]/a Storage=persistent" "$f"

            found=true
    fi
done

# if section not in any file, append section with key = value to FIRST file in files parameter
if ! $found ; then
    file=$(echo "/etc/systemd/journald.conf.d/complianceascode_hardening.conf /etc/systemd/journald.conf.d/*.conf /etc/systemd/journald.conf" | cut -f1 -d ' ')
    mkdir -p "$(dirname "$file")"

    echo -e "[Journal]\nStorage=persistent" >> "$file"

fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Disable systemd-journal-remote Socket [ref]

Journald supports the ability to receive messages from remote hosts, thus acting as a log server. Clients should not receive data from other hosts. NOTE: The same package, systemd-journal-remote , is used for both sending logs to remote hosts and receiving incoming logs. With regards to receiving logs, there are two Systemd unit files; systemd-journal-remote.socket and systemd-journal-remote.service.

Rationale:

If a client is configured to also receive data, thus turning it into a server, the client system is acting outside it's operational boundary.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_socket_systemd-journal-remote_disabled

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - socket_systemd-journal-remote_disabled

- name: Disable systemd-journal-remote Socket - Collect systemd Socket Units Present
    in the System
  ansible.builtin.command:
    cmd: systemctl -q list-unit-files --type socket
  register: result_systemd_unit_files
  changed_when: false
  when: '"kernel" in ansible_facts.packages'
  tags:
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - socket_systemd-journal-remote_disabled

- name: Disable systemd-journal-remote Socket - Ensure systemd-journal-remote.socket
    is Masked
  ansible.builtin.systemd:
    name: systemd-journal-remote.socket
    state: stopped
    enabled: false
    masked: true
  when:
  - '"kernel" in ansible_facts.packages'
  - result_systemd_unit_files.stdout_lines is search("systemd-journal-remote.socket")
  tags:
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - socket_systemd-journal-remote_disabled

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

SOCKET_NAME="systemd-journal-remote.socket"
SYSTEMCTL_EXEC='/usr/bin/systemctl'

if "$SYSTEMCTL_EXEC" -q list-unit-files --type socket | grep -q "$SOCKET_NAME"; then
    "$SYSTEMCTL_EXEC" stop "$SOCKET_NAME"
    "$SYSTEMCTL_EXEC" mask "$SOCKET_NAME"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Group Network Configuration and Firewalls Group contains 9 groups and 24 rules

[ref] Most systems must be connected to a network of some sort, and this brings with it the substantial risk of network attack. This section discusses the security impact of decisions about networking which must be made when configuring a system.

This section also discusses firewalls, network access controls, and other network security frameworks, which allow system-level rules to be written that can limit an attackers' ability to connect to your system. These rules can specify that network traffic should be allowed or denied from certain IP addresses, hosts, and networks. The rules can also specify which of the system's network services are available to particular hosts or networks.

Group firewalld Group contains 1 group and 2 rules

[ref] The dynamic firewall daemon firewalld provides a dynamically managed firewall with support for network “zones” to assign a level of trust to a network and its associated connections and interfaces. It has support for IPv4 and IPv6 firewall settings. It supports Ethernet bridges and has a separation of runtime and permanent configuration options. It also has an interface for services or applications to add firewall rules directly.
A graphical configuration tool, firewall-config, is used to configure firewalld, which in turn uses iptables tool to communicate with Netfilter in the kernel which implements packet filtering.
The firewall service provided by firewalld is dynamic rather than static because changes to the configuration can be made at anytime and are immediately implemented. There is no need to save or apply the changes. No unintended disruption of existing network connections occurs as no part of the firewall has to be reloaded.

Group Inspect and Activate Default firewalld Rules Group contains 2 rules

[ref] Firewalls can be used to separate networks into different zones based on the level of trust the user has decided to place on the devices and traffic within that network. NetworkManager informs firewalld to which zone an interface belongs. An interface's assigned zone can be changed by NetworkManager or via the firewall-config tool.
The zone settings in /etc/firewalld/ are a range of preset settings which can be quickly applied to a network interface. These are the zones provided by firewalld sorted according to the default trust level of the zones from untrusted to trusted:

drop
Any incoming network packets are dropped, there is no reply. Only outgoing network connections are possible.
block
Any incoming network connections are rejected with an icmp-host-prohibited message for IPv4 and icmp6-adm-prohibited for IPv6. Only network connections initiated from within the system are possible.
public
For use in public areas. You do not trust the other computers on the network to not harm your computer. Only selected incoming connections are accepted.
external
For use on external networks with masquerading enabled especially for routers. You do not trust the other computers on the network to not harm your computer. Only selected incoming connections are accepted.
dmz
For computers in your demilitarized zone that are publicly-accessible with limited access to your internal network. Only selected incoming connections are accepted.
work
For use in work areas. You mostly trust the other computers on networks to not harm your computer. Only selected incoming connections are accepted.
home
For use in home areas. You mostly trust the other computers on networks to not harm your computer. Only selected incoming connections are accepted.
internal
For use on internal networks. You mostly trust the other computers on the networks to not harm your computer. Only selected incoming connections are accepted.
trusted
All network connections are accepted.

It is possible to designate one of these zones to be the default zone. When interface connections are added to NetworkManager, they are assigned to the default zone. On installation, the default zone in firewalld is set to be the public zone.
To find out all the settings of a zone, for example the public zone, enter the following command as root:

# firewall-cmd --zone=public --list-all

Example output of this command might look like the following:

# firewall-cmd --zone=public --list-all
public
  interfaces:
  services: mdns dhcpv6-client ssh
  ports:
  forward-ports:
  icmp-blocks: source-quench

To view the network zones currently active, enter the following command as root:

# firewall-cmd --get-service

The following listing displays the result of this command on common Fedora system:

# firewall-cmd --get-service
amanda-client bacula bacula-client dhcp dhcpv6 dhcpv6-client dns ftp
high-availability http https imaps ipp ipp-client ipsec kerberos kpasswd
ldap ldaps libvirt libvirt-tls mdns mountd ms-wbt mysql nfs ntp openvpn
pmcd pmproxy pmwebapi pmwebapis pop3s postgresql proxy-dhcp radius rpc-bind
samba samba-client smtp ssh telnet tftp tftp-client transmission-client
vnc-server wbem-https

Finally to view the network zones that will be active after the next firewalld service reload, enter the following command as root:

# firewall-cmd --get-service --permanent

Rule Install firewalld Package [ref]

The firewalld package can be installed with the following command:

$ sudo dnf install firewalld

Rationale:

"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. Fedora 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)."

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_package_firewalld_installed

References:

disa	CCI-000382, CCI-000366, CCI-002314, CCI-002322
nist	CM-6(a)
ospp	FMT_SMF_EXT.1
os-srg	SRG-OS-000096-GPOS-00050, SRG-OS-000297-GPOS-00115, SRG-OS-000298-GPOS-00116, SRG-OS-000480-GPOS-00227, SRG-OS-000480-GPOS-00232
pcidss4	1.2.1, 1.2

Remediation Puppet snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable

include install_firewalld

class install_firewalld {
  package { 'firewalld':
    ensure => 'installed',
  }
}

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-53-CM-6(a)
  - PCI-DSSv4-1.2
  - PCI-DSSv4-1.2.1
  - enable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - package_firewalld_installed

- name: Ensure firewalld is installed
  package:
    name: firewalld
    state: present
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-53-CM-6(a)
  - PCI-DSSv4-1.2
  - PCI-DSSv4-1.2.1
  - enable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - package_firewalld_installed

Remediation script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable


package install firewalld

Remediation OSBuild Blueprint snippet ⇲


[[packages]]
name = "firewalld"
version = "*"

Remediation script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable


dnf install firewalld

Remediation Anaconda snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable


package --add=firewalld

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

if ! rpm -q --quiet "firewalld" ; then
    dnf install -y "firewalld"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Verify firewalld Enabled [ref]

The firewalld service can be enabled with the following command:

$ sudo systemctl enable firewalld.service

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_service_firewalld_enabled

References:

cis-csc	11, 3, 9
cobit5	BAI10.01, BAI10.02, BAI10.03, BAI10.05
cui	3.1.3, 3.4.7
disa	CCI-000382, CCI-000366, CCI-002314
isa-62443-2009	4.3.4.3.2, 4.3.4.3.3
isa-62443-2013	SR 7.6
iso27001-2013	A.12.1.2, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4
nerc-cip	CIP-003-8 R4, CIP-003-8 R5, CIP-004-6 R3
nist	AC-4, CM-7(b), CA-3(5), SC-7(21), CM-6(a)
nist-csf	PR.IP-1
ospp	FMT_SMF_EXT.1
os-srg	SRG-OS-000096-GPOS-00050, SRG-OS-000297-GPOS-00115, SRG-OS-000480-GPOS-00227, SRG-OS-000480-GPOS-00231, SRG-OS-000480-GPOS-00232
bsi	SYS.1.6.A5, SYS.1.6.A21
pcidss4	1.2.1, 1.2

Remediation Puppet snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable

include enable_firewalld

class enable_firewalld {
  service {'firewalld':
    enable => true,
    ensure => 'running',
  }
}

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.1.3
  - NIST-800-171-3.4.7
  - NIST-800-53-AC-4
  - NIST-800-53-CA-3(5)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(21)
  - PCI-DSSv4-1.2
  - PCI-DSSv4-1.2.1
  - enable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_firewalld_enabled

- name: Verify firewalld Enabled - Enable service firewalld
  block:

  - name: Gather the package facts
    package_facts:
      manager: auto

  - name: Verify firewalld Enabled - Enable Service firewalld
    ansible.builtin.systemd:
      name: firewalld
      enabled: true
      state: started
      masked: false
    when:
    - '"firewalld" in ansible_facts.packages'
  when:
  - '"kernel" in ansible_facts.packages'
  - '"firewalld" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.3
  - NIST-800-171-3.4.7
  - NIST-800-53-AC-4
  - NIST-800-53-CA-3(5)
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(21)
  - PCI-DSSv4-1.2
  - PCI-DSSv4-1.2.1
  - enable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_firewalld_enabled

Remediation script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	disable


service enable firewalld

Remediation OSBuild Blueprint snippet ⇲


[customizations.services]
enabled = ["firewalld"]

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel && { rpm --quiet -q firewalld; }; then

SYSTEMCTL_EXEC='/usr/bin/systemctl'
"$SYSTEMCTL_EXEC" unmask 'firewalld.service'
"$SYSTEMCTL_EXEC" start 'firewalld.service'
"$SYSTEMCTL_EXEC" enable 'firewalld.service'

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Group IPv6 Group contains 1 group and 4 rules

[ref] The system includes support for Internet Protocol version 6. A major and often-mentioned improvement over IPv4 is its enormous increase in the number of available addresses. Another important feature is its support for automatic configuration of many network settings.

Group Configure IPv6 Settings if Necessary Group contains 4 rules

[ref] A major feature of IPv6 is the extent to which systems implementing it can automatically configure their networking devices using information from the network. From a security perspective, manually configuring important configuration information is preferable to accepting it from the network in an unauthenticated fashion.

Rule Disable Accepting ICMP Redirects for All IPv6 Interfaces [ref]

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=0

To 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

Rationale:

An illicit ICMP redirect message could result in a man-in-the-middle attack.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv6_conf_all_accept_redirects

References:

cis-csc	11, 14, 3, 9
cobit5	BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS05.02, DSS05.05, DSS06.06
cui	3.1.20
disa	CCI-000366
isa-62443-2009	4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3
isa-62443-2013	SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 7.6
iso27001-2013	A.12.1.2, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4, A.9.1.2
nist	CM-7(a), CM-7(b), CM-6(a), CM-6(b), CM-6.1(iv)
nist-csf	PR.IP-1, PR.PT-3
os-srg	SRG-OS-000480-GPOS-00227
anssi	R13

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-6(b)
  - NIST-800-53-CM-6.1(iv)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv6_conf_all_accept_redirects

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv6.conf.all.accept_redirects.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-6(b)
  - NIST-800-53-CM-6.1(iv)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv6_conf_all_accept_redirects

- name: Comment out any occurrences of net.ipv6.conf.all.accept_redirects from config
    files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv6.conf.all.accept_redirects
    replace: '#net.ipv6.conf.all.accept_redirects'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-6(b)
  - NIST-800-53-CM-6.1(iv)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv6_conf_all_accept_redirects
- name: XCCDF Value sysctl_net_ipv6_conf_all_accept_redirects_value # promote to variable
  set_fact:
    sysctl_net_ipv6_conf_all_accept_redirects_value: !!str 0
  tags:
    - always

- name: Ensure sysctl net.ipv6.conf.all.accept_redirects is set
  sysctl:
    name: net.ipv6.conf.all.accept_redirects
    value: '{{ sysctl_net_ipv6_conf_all_accept_redirects_value }}'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-6(b)
  - NIST-800-53-CM-6.1(iv)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv6_conf_all_accept_redirects

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv6.conf.all.accept_redirects%3D0%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv6_conf_all_accept_redirects.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv6.conf.all.accept_redirects from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv6.conf.all.accept_redirects.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv6.conf.all.accept_redirects" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"

sysctl_net_ipv6_conf_all_accept_redirects_value='0'


#
# Set runtime for net.ipv6.conf.all.accept_redirects
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv6.conf.all.accept_redirects="$sysctl_net_ipv6_conf_all_accept_redirects_value"
fi

#
# If net.ipv6.conf.all.accept_redirects present in /etc/sysctl.conf, change value to appropriate value
#	else, add "net.ipv6.conf.all.accept_redirects = value" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv6.conf.all.accept_redirects")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$sysctl_net_ipv6_conf_all_accept_redirects_value"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv6.conf.all.accept_redirects\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv6.conf.all.accept_redirects\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Disable Kernel Parameter for Accepting Source-Routed Packets on all IPv6 Interfaces [ref]

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=0

To 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

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv6_conf_all_accept_source_route

References:

cis-csc	1, 12, 13, 14, 15, 16, 18, 4, 6, 8, 9
cobit5	APO01.06, APO13.01, DSS01.05, DSS03.01, DSS05.02, DSS05.04, DSS05.07, DSS06.02
cui	3.1.20
disa	CCI-000366
isa-62443-2009	4.2.3.4, 4.3.3.4, 4.4.3.3
isa-62443-2013	SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 7.1, SR 7.6
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.1, A.12.1.2, A.13.1.1, A.13.1.2, A.13.1.3, A.13.2.1, A.13.2.2, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-7(a), CM-7(b), CM-6(a)
nist-csf	DE.AE-1, ID.AM-3, PR.AC-5, PR.DS-5, PR.PT-4
os-srg	SRG-OS-000480-GPOS-00227
anssi	R13

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv6_conf_all_accept_source_route

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv6.conf.all.accept_source_route.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv6_conf_all_accept_source_route

- name: Comment out any occurrences of net.ipv6.conf.all.accept_source_route from
    config files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv6.conf.all.accept_source_route
    replace: '#net.ipv6.conf.all.accept_source_route'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv6_conf_all_accept_source_route
- name: XCCDF Value sysctl_net_ipv6_conf_all_accept_source_route_value # promote to variable
  set_fact:
    sysctl_net_ipv6_conf_all_accept_source_route_value: !!str 0
  tags:
    - always

- name: Ensure sysctl net.ipv6.conf.all.accept_source_route is set
  sysctl:
    name: net.ipv6.conf.all.accept_source_route
    value: '{{ sysctl_net_ipv6_conf_all_accept_source_route_value }}'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv6_conf_all_accept_source_route

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv6.conf.all.accept_source_route%3D0%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv6_conf_all_accept_source_route.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv6.conf.all.accept_source_route from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv6.conf.all.accept_source_route.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv6.conf.all.accept_source_route" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"

sysctl_net_ipv6_conf_all_accept_source_route_value='0'


#
# Set runtime for net.ipv6.conf.all.accept_source_route
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv6.conf.all.accept_source_route="$sysctl_net_ipv6_conf_all_accept_source_route_value"
fi

#
# If net.ipv6.conf.all.accept_source_route present in /etc/sysctl.conf, change value to appropriate value
#	else, add "net.ipv6.conf.all.accept_source_route = value" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv6.conf.all.accept_source_route")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$sysctl_net_ipv6_conf_all_accept_source_route_value"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv6.conf.all.accept_source_route\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv6.conf.all.accept_source_route\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Disable Kernel Parameter for Accepting ICMP Redirects by Default on IPv6 Interfaces [ref]

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=0

To 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

Rationale:

An illicit ICMP redirect message could result in a man-in-the-middle attack.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv6_conf_default_accept_redirects

References:

cis-csc	11, 14, 3, 9
cobit5	BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS05.02, DSS05.05, DSS06.06
cui	3.1.20
disa	CCI-000366
isa-62443-2009	4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3
isa-62443-2013	SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 7.6
iso27001-2013	A.12.1.2, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4, A.9.1.2
nist	CM-7(a), CM-7(b), CM-6(a)
nist-csf	PR.IP-1, PR.PT-3
os-srg	SRG-OS-000480-GPOS-00227
anssi	R13

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv6_conf_default_accept_redirects

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv6.conf.default.accept_redirects.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv6_conf_default_accept_redirects

- name: Comment out any occurrences of net.ipv6.conf.default.accept_redirects from
    config files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv6.conf.default.accept_redirects
    replace: '#net.ipv6.conf.default.accept_redirects'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv6_conf_default_accept_redirects
- name: XCCDF Value sysctl_net_ipv6_conf_default_accept_redirects_value # promote to variable
  set_fact:
    sysctl_net_ipv6_conf_default_accept_redirects_value: !!str 0
  tags:
    - always

- name: Ensure sysctl net.ipv6.conf.default.accept_redirects is set
  sysctl:
    name: net.ipv6.conf.default.accept_redirects
    value: '{{ sysctl_net_ipv6_conf_default_accept_redirects_value }}'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv6_conf_default_accept_redirects

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv6.conf.default.accept_redirects%20%3D%200%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv6_conf_default_accept_redirects.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv6.conf.default.accept_redirects from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv6.conf.default.accept_redirects.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv6.conf.default.accept_redirects" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"

sysctl_net_ipv6_conf_default_accept_redirects_value='0'


#
# Set runtime for net.ipv6.conf.default.accept_redirects
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv6.conf.default.accept_redirects="$sysctl_net_ipv6_conf_default_accept_redirects_value"
fi

#
# If net.ipv6.conf.default.accept_redirects present in /etc/sysctl.conf, change value to appropriate value
#	else, add "net.ipv6.conf.default.accept_redirects = value" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv6.conf.default.accept_redirects")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$sysctl_net_ipv6_conf_default_accept_redirects_value"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv6.conf.default.accept_redirects\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv6.conf.default.accept_redirects\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Disable Kernel Parameter for Accepting Source-Routed Packets on IPv6 Interfaces by Default [ref]

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=0

To 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

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv6_conf_default_accept_source_route

References:

cis-csc	1, 12, 13, 14, 15, 16, 18, 4, 6, 8, 9
cobit5	APO01.06, APO13.01, DSS01.05, DSS03.01, DSS05.02, DSS05.04, DSS05.07, DSS06.02
cui	3.1.20
disa	CCI-000366
isa-62443-2009	4.2.3.4, 4.3.3.4, 4.4.3.3
isa-62443-2013	SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 7.1, SR 7.6
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.1, A.12.1.2, A.13.1.1, A.13.1.2, A.13.1.3, A.13.2.1, A.13.2.2, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-7(a), CM-7(b), CM-6(a), CM-6(b), CM-6.1(iv)
nist-csf	DE.AE-1, ID.AM-3, PR.AC-5, PR.DS-5, PR.PT-4
pcidss	Req-1.4.3
os-srg	SRG-OS-000480-GPOS-00227
anssi	R13
pcidss4	1.4.2, 1.4

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-6(b)
  - NIST-800-53-CM-6.1(iv)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv6_conf_default_accept_source_route

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv6.conf.default.accept_source_route.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-6(b)
  - NIST-800-53-CM-6.1(iv)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv6_conf_default_accept_source_route

- name: Comment out any occurrences of net.ipv6.conf.default.accept_source_route from
    config files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv6.conf.default.accept_source_route
    replace: '#net.ipv6.conf.default.accept_source_route'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-6(b)
  - NIST-800-53-CM-6.1(iv)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv6_conf_default_accept_source_route
- name: XCCDF Value sysctl_net_ipv6_conf_default_accept_source_route_value # promote to variable
  set_fact:
    sysctl_net_ipv6_conf_default_accept_source_route_value: !!str 0
  tags:
    - always

- name: Ensure sysctl net.ipv6.conf.default.accept_source_route is set
  sysctl:
    name: net.ipv6.conf.default.accept_source_route
    value: '{{ sysctl_net_ipv6_conf_default_accept_source_route_value }}'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-6(b)
  - NIST-800-53-CM-6.1(iv)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv6_conf_default_accept_source_route

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv6.conf.default.accept_source_route%3D0%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv6_conf_default_accept_source_route.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv6.conf.default.accept_source_route from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv6.conf.default.accept_source_route.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv6.conf.default.accept_source_route" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"

sysctl_net_ipv6_conf_default_accept_source_route_value='0'


#
# Set runtime for net.ipv6.conf.default.accept_source_route
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv6.conf.default.accept_source_route="$sysctl_net_ipv6_conf_default_accept_source_route_value"
fi

#
# If net.ipv6.conf.default.accept_source_route present in /etc/sysctl.conf, change value to appropriate value
#	else, add "net.ipv6.conf.default.accept_source_route = value" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv6.conf.default.accept_source_route")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$sysctl_net_ipv6_conf_default_accept_source_route_value"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv6.conf.default.accept_source_route\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv6.conf.default.accept_source_route\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Group Kernel Parameters Which Affect Networking Group contains 2 groups and 15 rules

[ref] The sysctl utility is used to set parameters which affect the operation of the Linux kernel. Kernel parameters which affect networking and have security implications are described here.

Group Network Related Kernel Runtime Parameters for Hosts and Routers Group contains 13 rules

[ref] Certain kernel parameters should be set for systems which are acting as either hosts or routers to improve the system's ability defend against certain types of IPv4 protocol attacks.

Rule Disable Accepting ICMP Redirects for All IPv4 Interfaces [ref]

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=0

To 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

Rationale:

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."

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv4_conf_all_accept_redirects

References:

cis-csc	1, 11, 12, 13, 14, 15, 16, 2, 3, 7, 8, 9
cjis	5.10.1.1
cobit5	APO13.01, BAI04.04, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.03, DSS03.05, DSS05.02, DSS05.05, DSS05.07, DSS06.06
cui	3.1.20
disa	CCI-000366
isa-62443-2009	4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3
isa-62443-2013	SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 6.2, SR 7.1, SR 7.2, SR 7.6
iso27001-2013	A.12.1.2, A.12.1.3, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4, A.17.2.1, A.9.1.2
nist	CM-7(a), CM-7(b), CM-6(a), SC-7(a)
nist-csf	DE.CM-1, PR.DS-4, PR.IP-1, PR.PT-3
os-srg	SRG-OS-000480-GPOS-00227
anssi	R12

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_accept_redirects

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv4.conf.all.accept_redirects.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_accept_redirects

- name: Comment out any occurrences of net.ipv4.conf.all.accept_redirects from config
    files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv4.conf.all.accept_redirects
    replace: '#net.ipv4.conf.all.accept_redirects'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_accept_redirects
- name: XCCDF Value sysctl_net_ipv4_conf_all_accept_redirects_value # promote to variable
  set_fact:
    sysctl_net_ipv4_conf_all_accept_redirects_value: !!str 0
  tags:
    - always

- name: Ensure sysctl net.ipv4.conf.all.accept_redirects is set
  sysctl:
    name: net.ipv4.conf.all.accept_redirects
    value: '{{ sysctl_net_ipv4_conf_all_accept_redirects_value }}'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_accept_redirects

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv4.conf.all.accept_redirects%3D0%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv4_conf_all_accept_redirects.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv4.conf.all.accept_redirects from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv4.conf.all.accept_redirects.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv4.conf.all.accept_redirects" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"

sysctl_net_ipv4_conf_all_accept_redirects_value='0'


#
# Set runtime for net.ipv4.conf.all.accept_redirects
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv4.conf.all.accept_redirects="$sysctl_net_ipv4_conf_all_accept_redirects_value"
fi

#
# If net.ipv4.conf.all.accept_redirects present in /etc/sysctl.conf, change value to appropriate value
#	else, add "net.ipv4.conf.all.accept_redirects = value" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv4.conf.all.accept_redirects")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$sysctl_net_ipv4_conf_all_accept_redirects_value"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv4.conf.all.accept_redirects\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv4.conf.all.accept_redirects\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Disable Kernel Parameter for Accepting Source-Routed Packets on all IPv4 Interfaces [ref]

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=0

To 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

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv4_conf_all_accept_source_route

References:

cis-csc	1, 11, 12, 13, 14, 15, 16, 18, 2, 3, 4, 6, 7, 8, 9
cobit5	APO01.06, APO13.01, BAI04.04, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.03, DSS01.05, DSS03.01, DSS03.05, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS06.02, DSS06.06
cui	3.1.20
disa	CCI-000366
isa-62443-2009	4.2.3.4, 4.3.3.4, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, 4.4.3.3
isa-62443-2013	SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 6.2, SR 7.1, SR 7.2, SR 7.6
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.1, A.12.1.2, A.12.1.3, A.12.5.1, A.12.6.2, A.13.1.1, A.13.1.2, A.13.1.3, A.13.2.1, A.13.2.2, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.17.2.1, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nerc-cip	CIP-007-3 R4, CIP-007-3 R4.1, CIP-007-3 R4.2, CIP-007-3 R5.1
nist	CM-7(a), CM-7(b), SC-5, CM-6(a), SC-7(a)
nist-csf	DE.AE-1, DE.CM-1, ID.AM-3, PR.AC-5, PR.DS-4, PR.DS-5, PR.IP-1, PR.PT-3, PR.PT-4
os-srg	SRG-OS-000480-GPOS-00227
anssi	R12

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_accept_source_route

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv4.conf.all.accept_source_route.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_accept_source_route

- name: Comment out any occurrences of net.ipv4.conf.all.accept_source_route from
    config files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv4.conf.all.accept_source_route
    replace: '#net.ipv4.conf.all.accept_source_route'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_accept_source_route
- name: XCCDF Value sysctl_net_ipv4_conf_all_accept_source_route_value # promote to variable
  set_fact:
    sysctl_net_ipv4_conf_all_accept_source_route_value: !!str 0
  tags:
    - always

- name: Ensure sysctl net.ipv4.conf.all.accept_source_route is set
  sysctl:
    name: net.ipv4.conf.all.accept_source_route
    value: '{{ sysctl_net_ipv4_conf_all_accept_source_route_value }}'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_accept_source_route

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv4.conf.all.accept_source_route%3D0%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv4_conf_all_accept_source_route.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv4.conf.all.accept_source_route from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv4.conf.all.accept_source_route.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv4.conf.all.accept_source_route" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"

sysctl_net_ipv4_conf_all_accept_source_route_value='0'


#
# Set runtime for net.ipv4.conf.all.accept_source_route
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv4.conf.all.accept_source_route="$sysctl_net_ipv4_conf_all_accept_source_route_value"
fi

#
# If net.ipv4.conf.all.accept_source_route present in /etc/sysctl.conf, change value to appropriate value
#	else, add "net.ipv4.conf.all.accept_source_route = value" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv4.conf.all.accept_source_route")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$sysctl_net_ipv4_conf_all_accept_source_route_value"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv4.conf.all.accept_source_route\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv4.conf.all.accept_source_route\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Enable Kernel Parameter to Log Martian Packets on all IPv4 Interfaces [ref]

To set the runtime status of the net.ipv4.conf.all.log_martians kernel parameter, run the following command:

$ sudo sysctl -w net.ipv4.conf.all.log_martians=1

To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d:

net.ipv4.conf.all.log_martians = 1

Rationale:

The presence of "martian" packets (which have impossible addresses) as well as spoofed packets, source-routed packets, and redirects could be a sign of nefarious network activity. Logging these packets enables this activity to be detected.

Severity:

unknown

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv4_conf_all_log_martians

References:

cis-csc	1, 11, 12, 13, 14, 15, 16, 2, 3, 7, 8, 9
cobit5	APO13.01, BAI04.04, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.03, DSS01.04, DSS03.05, DSS05.02, DSS05.03, DSS05.05, DSS05.07, DSS06.06
cui	3.1.20
disa	CCI-000366
isa-62443-2009	4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3
isa-62443-2013	SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 6.2, SR 7.1, SR 7.2, SR 7.6
iso27001-2013	A.11.2.6, A.12.1.2, A.12.1.3, A.12.5.1, A.12.6.2, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.17.2.1, A.6.2.1, A.6.2.2, A.9.1.2
nist	CM-7(a), CM-7(b), SC-5(3)(a)
nist-csf	DE.CM-1, PR.AC-3, PR.DS-4, PR.IP-1, PR.PT-3, PR.PT-4
os-srg	SRG-OS-000480-GPOS-00227

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5(3)(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - reboot_required
  - sysctl_net_ipv4_conf_all_log_martians
  - unknown_severity

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv4.conf.all.log_martians.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5(3)(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - reboot_required
  - sysctl_net_ipv4_conf_all_log_martians
  - unknown_severity

- name: Comment out any occurrences of net.ipv4.conf.all.log_martians from config
    files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv4.conf.all.log_martians
    replace: '#net.ipv4.conf.all.log_martians'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5(3)(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - reboot_required
  - sysctl_net_ipv4_conf_all_log_martians
  - unknown_severity
- name: XCCDF Value sysctl_net_ipv4_conf_all_log_martians_value # promote to variable
  set_fact:
    sysctl_net_ipv4_conf_all_log_martians_value: !!str 1
  tags:
    - always

- name: Ensure sysctl net.ipv4.conf.all.log_martians is set
  sysctl:
    name: net.ipv4.conf.all.log_martians
    value: '{{ sysctl_net_ipv4_conf_all_log_martians_value }}'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5(3)(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - reboot_required
  - sysctl_net_ipv4_conf_all_log_martians
  - unknown_severity

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv4.conf.all.log_martians%3D1%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv4_conf_all_log_martians.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv4.conf.all.log_martians from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv4.conf.all.log_martians.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv4.conf.all.log_martians" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"

sysctl_net_ipv4_conf_all_log_martians_value='1'


#
# Set runtime for net.ipv4.conf.all.log_martians
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv4.conf.all.log_martians="$sysctl_net_ipv4_conf_all_log_martians_value"
fi

#
# If net.ipv4.conf.all.log_martians present in /etc/sysctl.conf, change value to appropriate value
#	else, add "net.ipv4.conf.all.log_martians = value" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv4.conf.all.log_martians")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$sysctl_net_ipv4_conf_all_log_martians_value"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv4.conf.all.log_martians\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv4.conf.all.log_martians\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Enable Kernel Parameter to Use Reverse Path Filtering on all IPv4 Interfaces [ref]

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=1

To 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

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv4_conf_all_rp_filter

References:

cis-csc	1, 12, 13, 14, 15, 16, 18, 2, 4, 6, 7, 8, 9
cobit5	APO01.06, APO13.01, BAI04.04, DSS01.03, DSS01.05, DSS03.01, DSS03.05, DSS05.02, DSS05.04, DSS05.07, DSS06.02
cui	3.1.20
disa	CCI-000366
isa-62443-2009	4.2.3.4, 4.3.3.4, 4.4.3.3
isa-62443-2013	SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 6.2, SR 7.1, SR 7.2, SR 7.6
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.1, A.12.1.2, A.12.1.3, A.13.1.1, A.13.1.2, A.13.1.3, A.13.2.1, A.13.2.2, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.17.2.1, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-7(a), CM-7(b), CM-6(a), SC-7(a)
nist-csf	DE.AE-1, DE.CM-1, ID.AM-3, PR.AC-5, PR.DS-4, PR.DS-5, PR.PT-4
pcidss	Req-1.4.3
os-srg	SRG-OS-000480-GPOS-00227
anssi	R12
pcidss4	1.4.3, 1.4

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.3
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_rp_filter

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv4.conf.all.rp_filter.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.3
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_rp_filter

- name: Comment out any occurrences of net.ipv4.conf.all.rp_filter from config files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv4.conf.all.rp_filter
    replace: '#net.ipv4.conf.all.rp_filter'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.3
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_rp_filter
- name: XCCDF Value sysctl_net_ipv4_conf_all_rp_filter_value # promote to variable
  set_fact:
    sysctl_net_ipv4_conf_all_rp_filter_value: !!str 1
  tags:
    - always

- name: Ensure sysctl net.ipv4.conf.all.rp_filter is set
  sysctl:
    name: net.ipv4.conf.all.rp_filter
    value: '{{ sysctl_net_ipv4_conf_all_rp_filter_value }}'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.3
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_rp_filter

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv4.conf.all.rp_filter%3D1%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv4_conf_all_rp_filter.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv4.conf.all.rp_filter from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv4.conf.all.rp_filter.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv4.conf.all.rp_filter" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"

sysctl_net_ipv4_conf_all_rp_filter_value='1'


#
# Set runtime for net.ipv4.conf.all.rp_filter
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv4.conf.all.rp_filter="$sysctl_net_ipv4_conf_all_rp_filter_value"
fi

#
# If net.ipv4.conf.all.rp_filter present in /etc/sysctl.conf, change value to appropriate value
#	else, add "net.ipv4.conf.all.rp_filter = value" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv4.conf.all.rp_filter")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$sysctl_net_ipv4_conf_all_rp_filter_value"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv4.conf.all.rp_filter\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv4.conf.all.rp_filter\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Disable Kernel Parameter for Accepting Secure ICMP Redirects on all IPv4 Interfaces [ref]

To set the runtime status of the net.ipv4.conf.all.secure_redirects kernel parameter, run the following command:

$ sudo sysctl -w net.ipv4.conf.all.secure_redirects=0

To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d:

net.ipv4.conf.all.secure_redirects = 0

Rationale:

Accepting "secure" ICMP redirects (from those gateways listed as default gateways) has few legitimate uses. It should be disabled unless it is absolutely required.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv4_conf_all_secure_redirects

References:

cis-csc	1, 11, 12, 13, 14, 15, 16, 18, 2, 3, 4, 6, 7, 8, 9
cobit5	APO01.06, APO13.01, BAI04.04, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.03, DSS01.05, DSS03.01, DSS03.05, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS06.02, DSS06.06
cui	3.1.20
disa	CCI-001503, CCI-001551
isa-62443-2009	4.2.3.4, 4.3.3.4, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, 4.4.3.3
isa-62443-2013	SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 6.2, SR 7.1, SR 7.2, SR 7.6
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.1, A.12.1.2, A.12.1.3, A.12.5.1, A.12.6.2, A.13.1.1, A.13.1.2, A.13.1.3, A.13.2.1, A.13.2.2, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.17.2.1, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-7(a), CM-7(b), CM-6(a), SC-7(a)
nist-csf	DE.AE-1, DE.CM-1, ID.AM-3, PR.AC-5, PR.DS-4, PR.DS-5, PR.IP-1, PR.PT-3, PR.PT-4
pcidss	Req-1.4.3
os-srg	SRG-OS-000480-GPOS-00227
anssi	R12
pcidss4	1.4.3, 1.4

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.3
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_secure_redirects

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv4.conf.all.secure_redirects.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.3
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_secure_redirects

- name: Comment out any occurrences of net.ipv4.conf.all.secure_redirects from config
    files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv4.conf.all.secure_redirects
    replace: '#net.ipv4.conf.all.secure_redirects'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.3
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_secure_redirects
- name: XCCDF Value sysctl_net_ipv4_conf_all_secure_redirects_value # promote to variable
  set_fact:
    sysctl_net_ipv4_conf_all_secure_redirects_value: !!str 0
  tags:
    - always

- name: Ensure sysctl net.ipv4.conf.all.secure_redirects is set
  sysctl:
    name: net.ipv4.conf.all.secure_redirects
    value: '{{ sysctl_net_ipv4_conf_all_secure_redirects_value }}'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.3
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_secure_redirects

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv4.conf.all.secure_redirects%3D0%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv4_conf_all_secure_redirects.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv4.conf.all.secure_redirects from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv4.conf.all.secure_redirects.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv4.conf.all.secure_redirects" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"

sysctl_net_ipv4_conf_all_secure_redirects_value='0'


#
# Set runtime for net.ipv4.conf.all.secure_redirects
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv4.conf.all.secure_redirects="$sysctl_net_ipv4_conf_all_secure_redirects_value"
fi

#
# If net.ipv4.conf.all.secure_redirects present in /etc/sysctl.conf, change value to appropriate value
#	else, add "net.ipv4.conf.all.secure_redirects = value" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv4.conf.all.secure_redirects")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$sysctl_net_ipv4_conf_all_secure_redirects_value"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv4.conf.all.secure_redirects\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv4.conf.all.secure_redirects\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Disable Kernel Parameter for Accepting ICMP Redirects by Default on IPv4 Interfaces [ref]

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=0

To 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

Rationale:

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv4_conf_default_accept_redirects

References:

cis-csc	1, 11, 12, 13, 14, 15, 16, 18, 2, 3, 4, 6, 7, 8, 9
cjis	5.10.1.1
cobit5	APO01.06, APO13.01, BAI04.04, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.03, DSS01.05, DSS03.01, DSS03.05, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS06.02, DSS06.06
cui	3.1.20
disa	CCI-000366
isa-62443-2009	4.2.3.4, 4.3.3.4, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, 4.4.3.3
isa-62443-2013	SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 6.2, SR 7.1, SR 7.2, SR 7.6
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.1, A.12.1.2, A.12.1.3, A.12.5.1, A.12.6.2, A.13.1.1, A.13.1.2, A.13.1.3, A.13.2.1, A.13.2.2, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.17.2.1, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-7(a), CM-7(b), CM-6(a), SC-7(a)
nist-csf	DE.AE-1, DE.CM-1, ID.AM-3, PR.AC-5, PR.DS-4, PR.DS-5, PR.IP-1, PR.PT-3, PR.PT-4
pcidss	Req-1.4.3
os-srg	SRG-OS-000480-GPOS-00227
anssi	R12
pcidss4	1.4.3, 1.4

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.3
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_accept_redirects

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv4.conf.default.accept_redirects.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.3
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_accept_redirects

- name: Comment out any occurrences of net.ipv4.conf.default.accept_redirects from
    config files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv4.conf.default.accept_redirects
    replace: '#net.ipv4.conf.default.accept_redirects'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.3
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_accept_redirects
- name: XCCDF Value sysctl_net_ipv4_conf_default_accept_redirects_value # promote to variable
  set_fact:
    sysctl_net_ipv4_conf_default_accept_redirects_value: !!str 0
  tags:
    - always

- name: Ensure sysctl net.ipv4.conf.default.accept_redirects is set
  sysctl:
    name: net.ipv4.conf.default.accept_redirects
    value: '{{ sysctl_net_ipv4_conf_default_accept_redirects_value }}'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.3
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_accept_redirects

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv4.conf.default.accept_redirects%3D0%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv4_conf_default_accept_redirects.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv4.conf.default.accept_redirects from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv4.conf.default.accept_redirects.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv4.conf.default.accept_redirects" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"

sysctl_net_ipv4_conf_default_accept_redirects_value='0'


#
# Set runtime for net.ipv4.conf.default.accept_redirects
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv4.conf.default.accept_redirects="$sysctl_net_ipv4_conf_default_accept_redirects_value"
fi

#
# If net.ipv4.conf.default.accept_redirects present in /etc/sysctl.conf, change value to appropriate value
#	else, add "net.ipv4.conf.default.accept_redirects = value" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv4.conf.default.accept_redirects")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$sysctl_net_ipv4_conf_default_accept_redirects_value"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv4.conf.default.accept_redirects\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv4.conf.default.accept_redirects\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Disable Kernel Parameter for Accepting Source-Routed Packets on IPv4 Interfaces by Default [ref]

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=0

To 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

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv4_conf_default_accept_source_route

References:

cis-csc	1, 11, 12, 13, 14, 15, 16, 18, 2, 3, 4, 6, 7, 8, 9
cjis	5.10.1.1
cobit5	APO01.06, APO13.01, BAI04.04, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.03, DSS01.05, DSS03.01, DSS03.05, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS06.02, DSS06.06
cui	3.1.20
disa	CCI-000366
isa-62443-2009	4.2.3.4, 4.3.3.4, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, 4.4.3.3
isa-62443-2013	SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 6.2, SR 7.1, SR 7.2, SR 7.6
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.1, A.12.1.2, A.12.1.3, A.12.5.1, A.12.6.2, A.13.1.1, A.13.1.2, A.13.1.3, A.13.2.1, A.13.2.2, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.17.2.1, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nerc-cip	CIP-007-3 R4, CIP-007-3 R4.1, CIP-007-3 R4.2, CIP-007-3 R5.1
nist	CM-7(a), CM-7(b), SC-5, SC-7(a)
nist-csf	DE.AE-1, DE.CM-1, ID.AM-3, PR.AC-5, PR.DS-4, PR.DS-5, PR.IP-1, PR.PT-3, PR.PT-4
os-srg	SRG-OS-000480-GPOS-00227
anssi	R12

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_accept_source_route

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv4.conf.default.accept_source_route.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_accept_source_route

- name: Comment out any occurrences of net.ipv4.conf.default.accept_source_route from
    config files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv4.conf.default.accept_source_route
    replace: '#net.ipv4.conf.default.accept_source_route'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_accept_source_route
- name: XCCDF Value sysctl_net_ipv4_conf_default_accept_source_route_value # promote to variable
  set_fact:
    sysctl_net_ipv4_conf_default_accept_source_route_value: !!str 0
  tags:
    - always

- name: Ensure sysctl net.ipv4.conf.default.accept_source_route is set
  sysctl:
    name: net.ipv4.conf.default.accept_source_route
    value: '{{ sysctl_net_ipv4_conf_default_accept_source_route_value }}'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_accept_source_route

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv4.conf.default.accept_source_route%3D0%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv4_conf_default_accept_source_route.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv4.conf.default.accept_source_route from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv4.conf.default.accept_source_route.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv4.conf.default.accept_source_route" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"

sysctl_net_ipv4_conf_default_accept_source_route_value='0'


#
# Set runtime for net.ipv4.conf.default.accept_source_route
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv4.conf.default.accept_source_route="$sysctl_net_ipv4_conf_default_accept_source_route_value"
fi

#
# If net.ipv4.conf.default.accept_source_route present in /etc/sysctl.conf, change value to appropriate value
#	else, add "net.ipv4.conf.default.accept_source_route = value" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv4.conf.default.accept_source_route")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$sysctl_net_ipv4_conf_default_accept_source_route_value"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv4.conf.default.accept_source_route\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv4.conf.default.accept_source_route\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Enable Kernel Paremeter to Log Martian Packets on all IPv4 Interfaces by Default [ref]

To set the runtime status of the net.ipv4.conf.default.log_martians kernel parameter, run the following command:

$ sudo sysctl -w net.ipv4.conf.default.log_martians=1

To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d:

net.ipv4.conf.default.log_martians = 1

Rationale:

Severity:

unknown

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv4_conf_default_log_martians

References:

cis-csc	1, 11, 12, 13, 14, 15, 16, 2, 3, 7, 8, 9
cobit5	APO13.01, BAI04.04, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.03, DSS01.04, DSS03.05, DSS05.02, DSS05.03, DSS05.05, DSS05.07, DSS06.06
cui	3.1.20
disa	CCI-000366
isa-62443-2009	4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3
isa-62443-2013	SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 6.2, SR 7.1, SR 7.2, SR 7.6
iso27001-2013	A.11.2.6, A.12.1.2, A.12.1.3, A.12.5.1, A.12.6.2, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.17.2.1, A.6.2.1, A.6.2.2, A.9.1.2
nist	CM-7(a), CM-7(b), SC-5(3)(a)
nist-csf	DE.CM-1, PR.AC-3, PR.DS-4, PR.IP-1, PR.PT-3, PR.PT-4
os-srg	SRG-OS-000480-GPOS-00227

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5(3)(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - reboot_required
  - sysctl_net_ipv4_conf_default_log_martians
  - unknown_severity

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv4.conf.default.log_martians.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5(3)(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - reboot_required
  - sysctl_net_ipv4_conf_default_log_martians
  - unknown_severity

- name: Comment out any occurrences of net.ipv4.conf.default.log_martians from config
    files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv4.conf.default.log_martians
    replace: '#net.ipv4.conf.default.log_martians'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5(3)(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - reboot_required
  - sysctl_net_ipv4_conf_default_log_martians
  - unknown_severity
- name: XCCDF Value sysctl_net_ipv4_conf_default_log_martians_value # promote to variable
  set_fact:
    sysctl_net_ipv4_conf_default_log_martians_value: !!str 1
  tags:
    - always

- name: Ensure sysctl net.ipv4.conf.default.log_martians is set
  sysctl:
    name: net.ipv4.conf.default.log_martians
    value: '{{ sysctl_net_ipv4_conf_default_log_martians_value }}'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5(3)(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - reboot_required
  - sysctl_net_ipv4_conf_default_log_martians
  - unknown_severity

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv4.conf.default.log_martians%3D1%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv4_conf_default_log_martians.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv4.conf.default.log_martians from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv4.conf.default.log_martians.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv4.conf.default.log_martians" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"

sysctl_net_ipv4_conf_default_log_martians_value='1'


#
# Set runtime for net.ipv4.conf.default.log_martians
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv4.conf.default.log_martians="$sysctl_net_ipv4_conf_default_log_martians_value"
fi

#
# If net.ipv4.conf.default.log_martians present in /etc/sysctl.conf, change value to appropriate value
#	else, add "net.ipv4.conf.default.log_martians = value" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv4.conf.default.log_martians")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$sysctl_net_ipv4_conf_default_log_martians_value"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv4.conf.default.log_martians\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv4.conf.default.log_martians\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Enable Kernel Parameter to Use Reverse Path Filtering on all IPv4 Interfaces by Default [ref]

To set the runtime status of the net.ipv4.conf.default.rp_filter kernel parameter, run the following command:

$ sudo sysctl -w net.ipv4.conf.default.rp_filter=1

To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d:

net.ipv4.conf.default.rp_filter = 1

Rationale:

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv4_conf_default_rp_filter

References:

cis-csc	1, 12, 13, 14, 15, 16, 18, 2, 4, 6, 7, 8, 9
cobit5	APO01.06, APO13.01, BAI04.04, DSS01.03, DSS01.05, DSS03.01, DSS03.05, DSS05.02, DSS05.04, DSS05.07, DSS06.02
cui	3.1.20
disa	CCI-000366
isa-62443-2009	4.2.3.4, 4.3.3.4, 4.4.3.3
isa-62443-2013	SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 6.2, SR 7.1, SR 7.2, SR 7.6
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.1, A.12.1.2, A.12.1.3, A.13.1.1, A.13.1.2, A.13.1.3, A.13.2.1, A.13.2.2, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.17.2.1, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-7(a), CM-7(b), CM-6(a), SC-7(a)
nist-csf	DE.AE-1, DE.CM-1, ID.AM-3, PR.AC-5, PR.DS-4, PR.DS-5, PR.PT-4
os-srg	SRG-OS-000480-GPOS-00227
anssi	R12

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_rp_filter

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv4.conf.default.rp_filter.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_rp_filter

- name: Comment out any occurrences of net.ipv4.conf.default.rp_filter from config
    files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv4.conf.default.rp_filter
    replace: '#net.ipv4.conf.default.rp_filter'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_rp_filter
- name: XCCDF Value sysctl_net_ipv4_conf_default_rp_filter_value # promote to variable
  set_fact:
    sysctl_net_ipv4_conf_default_rp_filter_value: !!str 1
  tags:
    - always

- name: Ensure sysctl net.ipv4.conf.default.rp_filter is set
  sysctl:
    name: net.ipv4.conf.default.rp_filter
    value: '{{ sysctl_net_ipv4_conf_default_rp_filter_value }}'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_rp_filter

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv4.conf.default.rp_filter%3D1%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv4_conf_default_rp_filter.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv4.conf.default.rp_filter from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv4.conf.default.rp_filter.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv4.conf.default.rp_filter" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"

sysctl_net_ipv4_conf_default_rp_filter_value='1'


#
# Set runtime for net.ipv4.conf.default.rp_filter
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv4.conf.default.rp_filter="$sysctl_net_ipv4_conf_default_rp_filter_value"
fi

#
# If net.ipv4.conf.default.rp_filter present in /etc/sysctl.conf, change value to appropriate value
#	else, add "net.ipv4.conf.default.rp_filter = value" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv4.conf.default.rp_filter")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$sysctl_net_ipv4_conf_default_rp_filter_value"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv4.conf.default.rp_filter\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv4.conf.default.rp_filter\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Configure Kernel Parameter for Accepting Secure Redirects By Default [ref]

To set the runtime status of the net.ipv4.conf.default.secure_redirects kernel parameter, run the following command:

$ sudo sysctl -w net.ipv4.conf.default.secure_redirects=0

To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d:

net.ipv4.conf.default.secure_redirects = 0

Rationale:

Accepting "secure" ICMP redirects (from those gateways listed as default gateways) has few legitimate uses. It should be disabled unless it is absolutely required.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv4_conf_default_secure_redirects

References:

cis-csc	1, 11, 12, 13, 14, 15, 16, 18, 2, 3, 4, 6, 7, 8, 9
cobit5	APO01.06, APO13.01, BAI04.04, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.03, DSS01.05, DSS03.01, DSS03.05, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS06.02, DSS06.06
cui	3.1.20
disa	CCI-001551
isa-62443-2009	4.2.3.4, 4.3.3.4, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, 4.4.3.3
isa-62443-2013	SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 6.2, SR 7.1, SR 7.2, SR 7.6
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.1, A.12.1.2, A.12.1.3, A.12.5.1, A.12.6.2, A.13.1.1, A.13.1.2, A.13.1.3, A.13.2.1, A.13.2.2, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.17.2.1, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nerc-cip	CIP-007-3 R4, CIP-007-3 R4.1, CIP-007-3 R4.2, CIP-007-3 R5.1
nist	CM-7(a), CM-7(b), SC-5, SC-7(a)
nist-csf	DE.AE-1, DE.CM-1, ID.AM-3, PR.AC-5, PR.DS-4, PR.DS-5, PR.IP-1, PR.PT-3, PR.PT-4
os-srg	SRG-OS-000480-GPOS-00227
anssi	R12

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_secure_redirects

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv4.conf.default.secure_redirects.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_secure_redirects

- name: Comment out any occurrences of net.ipv4.conf.default.secure_redirects from
    config files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv4.conf.default.secure_redirects
    replace: '#net.ipv4.conf.default.secure_redirects'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_secure_redirects
- name: XCCDF Value sysctl_net_ipv4_conf_default_secure_redirects_value # promote to variable
  set_fact:
    sysctl_net_ipv4_conf_default_secure_redirects_value: !!str 0
  tags:
    - always

- name: Ensure sysctl net.ipv4.conf.default.secure_redirects is set
  sysctl:
    name: net.ipv4.conf.default.secure_redirects
    value: '{{ sysctl_net_ipv4_conf_default_secure_redirects_value }}'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_secure_redirects

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv4.conf.default.secure_redirects%3D0%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv4_conf_default_secure_redirects.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv4.conf.default.secure_redirects from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv4.conf.default.secure_redirects.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv4.conf.default.secure_redirects" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"

sysctl_net_ipv4_conf_default_secure_redirects_value='0'


#
# Set runtime for net.ipv4.conf.default.secure_redirects
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv4.conf.default.secure_redirects="$sysctl_net_ipv4_conf_default_secure_redirects_value"
fi

#
# If net.ipv4.conf.default.secure_redirects present in /etc/sysctl.conf, change value to appropriate value
#	else, add "net.ipv4.conf.default.secure_redirects = value" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv4.conf.default.secure_redirects")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$sysctl_net_ipv4_conf_default_secure_redirects_value"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv4.conf.default.secure_redirects\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv4.conf.default.secure_redirects\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Enable Kernel Parameter to Ignore ICMP Broadcast Echo Requests on IPv4 Interfaces [ref]

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=1

To 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

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv4_icmp_echo_ignore_broadcasts

References:

cis-csc	1, 11, 12, 13, 14, 15, 16, 18, 2, 3, 4, 6, 7, 8, 9
cjis	5.10.1.1
cobit5	APO01.06, APO13.01, BAI04.04, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.03, DSS01.05, DSS03.01, DSS03.05, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS06.02, DSS06.06
cui	3.1.20
disa	CCI-000366
isa-62443-2009	4.2.3.4, 4.3.3.4, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, 4.4.3.3
isa-62443-2013	SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 6.2, SR 7.1, SR 7.2, SR 7.6
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.1, A.12.1.2, A.12.1.3, A.12.5.1, A.12.6.2, A.13.1.1, A.13.1.2, A.13.1.3, A.13.2.1, A.13.2.2, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.17.2.1, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nerc-cip	CIP-007-3 R4, CIP-007-3 R4.1, CIP-007-3 R4.2, CIP-007-3 R5.1
nist	CM-7(a), CM-7(b), SC-5
nist-csf	DE.AE-1, DE.CM-1, ID.AM-3, PR.AC-5, PR.DS-4, PR.DS-5, PR.IP-1, PR.PT-3, PR.PT-4
pcidss	Req-1.4.3
os-srg	SRG-OS-000480-GPOS-00227
pcidss4	1.4.2, 1.4

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_icmp_echo_ignore_broadcasts

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv4.icmp_echo_ignore_broadcasts.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_icmp_echo_ignore_broadcasts

- name: Comment out any occurrences of net.ipv4.icmp_echo_ignore_broadcasts from config
    files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv4.icmp_echo_ignore_broadcasts
    replace: '#net.ipv4.icmp_echo_ignore_broadcasts'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_icmp_echo_ignore_broadcasts
- name: XCCDF Value sysctl_net_ipv4_icmp_echo_ignore_broadcasts_value # promote to variable
  set_fact:
    sysctl_net_ipv4_icmp_echo_ignore_broadcasts_value: !!str 1
  tags:
    - always

- name: Ensure sysctl net.ipv4.icmp_echo_ignore_broadcasts is set
  sysctl:
    name: net.ipv4.icmp_echo_ignore_broadcasts
    value: '{{ sysctl_net_ipv4_icmp_echo_ignore_broadcasts_value }}'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_icmp_echo_ignore_broadcasts

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv4.icmp_echo_ignore_broadcasts%3D1%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv4_icmp_echo_ignore_broadcasts.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv4.icmp_echo_ignore_broadcasts from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv4.icmp_echo_ignore_broadcasts.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv4.icmp_echo_ignore_broadcasts" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"

sysctl_net_ipv4_icmp_echo_ignore_broadcasts_value='1'


#
# Set runtime for net.ipv4.icmp_echo_ignore_broadcasts
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv4.icmp_echo_ignore_broadcasts="$sysctl_net_ipv4_icmp_echo_ignore_broadcasts_value"
fi

#
# If net.ipv4.icmp_echo_ignore_broadcasts present in /etc/sysctl.conf, change value to appropriate value
#	else, add "net.ipv4.icmp_echo_ignore_broadcasts = value" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv4.icmp_echo_ignore_broadcasts")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$sysctl_net_ipv4_icmp_echo_ignore_broadcasts_value"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv4.icmp_echo_ignore_broadcasts\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv4.icmp_echo_ignore_broadcasts\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Enable Kernel Parameter to Ignore Bogus ICMP Error Responses on IPv4 Interfaces [ref]

To set the runtime status of the net.ipv4.icmp_ignore_bogus_error_responses kernel parameter, run the following command:

$ sudo sysctl -w net.ipv4.icmp_ignore_bogus_error_responses=1

To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d:

net.ipv4.icmp_ignore_bogus_error_responses = 1

Rationale:

Ignoring bogus ICMP error responses reduces log size, although some activity would not be logged.

Severity:

unknown

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv4_icmp_ignore_bogus_error_responses

References:

cis-csc	1, 11, 12, 13, 14, 15, 16, 2, 3, 7, 8, 9
cobit5	APO13.01, BAI04.04, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.03, DSS03.05, DSS05.02, DSS05.05, DSS05.07, DSS06.06
cui	3.1.20
disa	CCI-000366
isa-62443-2009	4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3
isa-62443-2013	SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 6.2, SR 7.1, SR 7.2, SR 7.6
iso27001-2013	A.12.1.2, A.12.1.3, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4, A.17.2.1, A.9.1.2
nerc-cip	CIP-007-3 R4, CIP-007-3 R4.1, CIP-007-3 R4.2, CIP-007-3 R5.1
nist	CM-7(a), CM-7(b), SC-5
nist-csf	DE.CM-1, PR.DS-4, PR.IP-1, PR.PT-3
pcidss	Req-1.4.3
os-srg	SRG-OS-000480-GPOS-00227
anssi	R12
pcidss4	1.4.2, 1.4

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - low_complexity
  - medium_disruption
  - reboot_required
  - sysctl_net_ipv4_icmp_ignore_bogus_error_responses
  - unknown_severity

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv4.icmp_ignore_bogus_error_responses.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - low_complexity
  - medium_disruption
  - reboot_required
  - sysctl_net_ipv4_icmp_ignore_bogus_error_responses
  - unknown_severity

- name: Comment out any occurrences of net.ipv4.icmp_ignore_bogus_error_responses
    from config files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv4.icmp_ignore_bogus_error_responses
    replace: '#net.ipv4.icmp_ignore_bogus_error_responses'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - low_complexity
  - medium_disruption
  - reboot_required
  - sysctl_net_ipv4_icmp_ignore_bogus_error_responses
  - unknown_severity
- name: XCCDF Value sysctl_net_ipv4_icmp_ignore_bogus_error_responses_value # promote to variable
  set_fact:
    sysctl_net_ipv4_icmp_ignore_bogus_error_responses_value: !!str 1
  tags:
    - always

- name: Ensure sysctl net.ipv4.icmp_ignore_bogus_error_responses is set
  sysctl:
    name: net.ipv4.icmp_ignore_bogus_error_responses
    value: '{{ sysctl_net_ipv4_icmp_ignore_bogus_error_responses_value }}'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - PCI-DSS-Req-1.4.3
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - low_complexity
  - medium_disruption
  - reboot_required
  - sysctl_net_ipv4_icmp_ignore_bogus_error_responses
  - unknown_severity

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv4.icmp_ignore_bogus_error_responses%3D1%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv4_icmp_ignore_bogus_error_responses.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv4.icmp_ignore_bogus_error_responses from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv4.icmp_ignore_bogus_error_responses.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv4.icmp_ignore_bogus_error_responses" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"

sysctl_net_ipv4_icmp_ignore_bogus_error_responses_value='1'


#
# Set runtime for net.ipv4.icmp_ignore_bogus_error_responses
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv4.icmp_ignore_bogus_error_responses="$sysctl_net_ipv4_icmp_ignore_bogus_error_responses_value"
fi

#
# If net.ipv4.icmp_ignore_bogus_error_responses present in /etc/sysctl.conf, change value to appropriate value
#	else, add "net.ipv4.icmp_ignore_bogus_error_responses = value" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv4.icmp_ignore_bogus_error_responses")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$sysctl_net_ipv4_icmp_ignore_bogus_error_responses_value"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv4.icmp_ignore_bogus_error_responses\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv4.icmp_ignore_bogus_error_responses\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Enable Kernel Parameter to Use TCP Syncookies on Network Interfaces [ref]

To set the runtime status of the net.ipv4.tcp_syncookies kernel parameter, run the following command:

$ sudo sysctl -w net.ipv4.tcp_syncookies=1

To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d:

net.ipv4.tcp_syncookies = 1

Rationale:

A TCP SYN flood attack can cause a denial of service by filling a system's TCP connection table with connections in the SYN_RCVD state. Syncookies can be used to track a connection when a subsequent ACK is received, verifying the initiator is attempting a valid connection and is not a flood source. This feature is activated when a flood condition is detected, and enables the system to continue servicing valid connection requests.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv4_tcp_syncookies

References:

cis-csc	1, 12, 13, 14, 15, 16, 18, 2, 4, 6, 7, 8, 9
cjis	5.10.1.1
cobit5	APO01.06, APO13.01, BAI04.04, DSS01.03, DSS01.05, DSS03.01, DSS03.05, DSS05.02, DSS05.04, DSS05.07, DSS06.02
cui	3.1.20
disa	CCI-001095, CCI-000366, CCI-002385
isa-62443-2009	4.2.3.4, 4.3.3.4, 4.4.3.3
isa-62443-2013	SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 6.2, SR 7.1, SR 7.2, SR 7.6
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.1, A.12.1.2, A.12.1.3, A.13.1.1, A.13.1.2, A.13.1.3, A.13.2.1, A.13.2.2, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.17.2.1, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nist	CM-7(a), CM-7(b), SC-5(1), SC-5(2), SC-5(3)(a), CM-6(a)
nist-csf	DE.AE-1, DE.CM-1, ID.AM-3, PR.AC-5, PR.DS-4, PR.DS-5, PR.PT-4
pcidss	Req-1.4.1
os-srg	SRG-OS-000480-GPOS-00227, SRG-OS-000420-GPOS-00186, SRG-OS-000142-GPOS-00071
anssi	R12
pcidss4	1.4.3, 1.4

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5(1)
  - NIST-800-53-SC-5(2)
  - NIST-800-53-SC-5(3)(a)
  - PCI-DSS-Req-1.4.1
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.3
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_tcp_syncookies

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv4.tcp_syncookies.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5(1)
  - NIST-800-53-SC-5(2)
  - NIST-800-53-SC-5(3)(a)
  - PCI-DSS-Req-1.4.1
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.3
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_tcp_syncookies

- name: Comment out any occurrences of net.ipv4.tcp_syncookies from config files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv4.tcp_syncookies
    replace: '#net.ipv4.tcp_syncookies'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5(1)
  - NIST-800-53-SC-5(2)
  - NIST-800-53-SC-5(3)(a)
  - PCI-DSS-Req-1.4.1
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.3
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_tcp_syncookies
- name: XCCDF Value sysctl_net_ipv4_tcp_syncookies_value # promote to variable
  set_fact:
    sysctl_net_ipv4_tcp_syncookies_value: !!str 1
  tags:
    - always

- name: Ensure sysctl net.ipv4.tcp_syncookies is set
  sysctl:
    name: net.ipv4.tcp_syncookies
    value: '{{ sysctl_net_ipv4_tcp_syncookies_value }}'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5(1)
  - NIST-800-53-SC-5(2)
  - NIST-800-53-SC-5(3)(a)
  - PCI-DSS-Req-1.4.1
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.3
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_tcp_syncookies

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv4.tcp_syncookies%3D1%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv4_tcp_syncookies.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv4.tcp_syncookies from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv4.tcp_syncookies.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv4.tcp_syncookies" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"

sysctl_net_ipv4_tcp_syncookies_value='1'


#
# Set runtime for net.ipv4.tcp_syncookies
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv4.tcp_syncookies="$sysctl_net_ipv4_tcp_syncookies_value"
fi

#
# If net.ipv4.tcp_syncookies present in /etc/sysctl.conf, change value to appropriate value
#	else, add "net.ipv4.tcp_syncookies = value" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv4.tcp_syncookies")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$sysctl_net_ipv4_tcp_syncookies_value"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv4.tcp_syncookies\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv4.tcp_syncookies\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Group Network Parameters for Hosts Only Group contains 2 rules

[ref] If the system is not going to be used as a router, then setting certain kernel parameters ensure that the host will not perform routing of network traffic.

Rule Disable Kernel Parameter for Sending ICMP Redirects on all IPv4 Interfaces [ref]

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=0

To 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

Rationale:

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.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv4_conf_all_send_redirects

References:

cis-csc	1, 11, 12, 13, 14, 15, 16, 18, 2, 3, 4, 6, 7, 8, 9
cjis	5.10.1.1
cobit5	APO01.06, APO13.01, BAI04.04, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.03, DSS01.05, DSS03.01, DSS03.05, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS06.02, DSS06.06
cui	3.1.20
disa	CCI-000366
isa-62443-2009	4.2.3.4, 4.3.3.4, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, 4.4.3.3
isa-62443-2013	SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 6.2, SR 7.1, SR 7.2, SR 7.6
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.1, A.12.1.2, A.12.1.3, A.12.5.1, A.12.6.2, A.13.1.1, A.13.1.2, A.13.1.3, A.13.2.1, A.13.2.2, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.17.2.1, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nerc-cip	CIP-007-3 R4, CIP-007-3 R4.1, CIP-007-3 R4.2, CIP-007-3 R5.1
nist	CM-7(a), CM-7(b), SC-5, CM-6(a), SC-7(a)
nist-csf	DE.AE-1, DE.CM-1, ID.AM-3, PR.AC-5, PR.DS-4, PR.DS-5, PR.IP-1, PR.PT-3, PR.PT-4
os-srg	SRG-OS-000480-GPOS-00227
anssi	R12
pcidss4	1.4.5, 1.4

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.5
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_send_redirects

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv4.conf.all.send_redirects.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.5
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_send_redirects

- name: Comment out any occurrences of net.ipv4.conf.all.send_redirects from config
    files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv4.conf.all.send_redirects
    replace: '#net.ipv4.conf.all.send_redirects'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.5
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_send_redirects

- name: Ensure sysctl net.ipv4.conf.all.send_redirects is set to 0
  sysctl:
    name: net.ipv4.conf.all.send_redirects
    value: '0'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.5
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_all_send_redirects

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv4.conf.all.send_redirects%3D0%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv4_conf_all_send_redirects.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv4.conf.all.send_redirects from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv4.conf.all.send_redirects.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv4.conf.all.send_redirects" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"


#
# Set runtime for net.ipv4.conf.all.send_redirects
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv4.conf.all.send_redirects="0"
fi

#
# If net.ipv4.conf.all.send_redirects present in /etc/sysctl.conf, change value to "0"
#	else, add "net.ipv4.conf.all.send_redirects = 0" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv4.conf.all.send_redirects")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "0"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv4.conf.all.send_redirects\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv4.conf.all.send_redirects\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Disable Kernel Parameter for Sending ICMP Redirects on all IPv4 Interfaces by Default [ref]

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=0

To 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

Rationale:

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_sysctl_net_ipv4_conf_default_send_redirects

References:

cis-csc	1, 11, 12, 13, 14, 15, 16, 18, 2, 3, 4, 6, 7, 8, 9
cjis	5.10.1.1
cobit5	APO01.06, APO13.01, BAI04.04, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.03, DSS01.05, DSS03.01, DSS03.05, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS06.02, DSS06.06
cui	3.1.20
disa	CCI-000366
isa-62443-2009	4.2.3.4, 4.3.3.4, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, 4.4.3.3
isa-62443-2013	SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 6.2, SR 7.1, SR 7.2, SR 7.6
iso27001-2013	A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.1, A.12.1.2, A.12.1.3, A.12.5.1, A.12.6.2, A.13.1.1, A.13.1.2, A.13.1.3, A.13.2.1, A.13.2.2, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.17.2.1, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5
nerc-cip	CIP-007-3 R4, CIP-007-3 R4.1, CIP-007-3 R4.2, CIP-007-3 R5.1
nist	CM-7(a), CM-7(b), SC-5, CM-6(a), SC-7(a)
nist-csf	DE.AE-1, DE.CM-1, ID.AM-3, PR.AC-5, PR.DS-4, PR.DS-5, PR.IP-1, PR.PT-3, PR.PT-4
os-srg	SRG-OS-000480-GPOS-00227
anssi	R12
pcidss4	1.4.5, 1.4

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.5
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_send_redirects

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*net.ipv4.conf.default.send_redirects.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.5
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_send_redirects

- name: Comment out any occurrences of net.ipv4.conf.default.send_redirects from config
    files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*net.ipv4.conf.default.send_redirects
    replace: '#net.ipv4.conf.default.send_redirects'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.5
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_send_redirects

- name: Ensure sysctl net.ipv4.conf.default.send_redirects is set to 0
  sysctl:
    name: net.ipv4.conf.default.send_redirects
    value: '0'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1.1
  - NIST-800-171-3.1.20
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-SC-5
  - NIST-800-53-SC-7(a)
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.5
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_net_ipv4_conf_default_send_redirects

Remediation Kubernetes snippet ⇲

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,net.ipv4.conf.default.send_redirects%3D0%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_net_ipv4_conf_default_send_redirects.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

# Comment out any occurrences of net.ipv4.conf.default.send_redirects from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do


  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*net.ipv4.conf.default.send_redirects.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "net.ipv4.conf.default.send_redirects" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"


#
# Set runtime for net.ipv4.conf.default.send_redirects
#
if [[ "$OSCAP_BOOTC_BUILD" != "YES" ]] ; then
    /sbin/sysctl -q -n -w net.ipv4.conf.default.send_redirects="0"
fi

#
# If net.ipv4.conf.default.send_redirects present in /etc/sysctl.conf, change value to "0"
#	else, add "net.ipv4.conf.default.send_redirects = 0" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^net.ipv4.conf.default.send_redirects")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "0"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^net.ipv4.conf.default.send_redirects\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^net.ipv4.conf.default.send_redirects\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Group nftables Group contains 1 rule

[ref]

If firewalld or iptables are being used in your environment, please follow the guidance in their
respective section and pass-over the guidance in this section.

nftables is a subsystem of the Linux kernel providing filtering and classification of network packets/datagrams/frames and is the successor to iptables. The biggest change with the successor nftables is its simplicity. With iptables, we have to configure every single rule and use the syntax which can be compared with normal commands. With nftables, the simpler syntax, much like BPF (Berkely Packet Filter) means shorter lines and less repetition. Support for nftables should also be compiled into the kernel, together with the related nftables modules.

It is available in Linux kernels >= 3.13. Please ensure that your kernel supports nftables before choosing this option.

Rule Verify nftables Service is Disabled [ref]

nftables is a subsystem of the Linux kernel providing filtering and classification of network packets/datagrams/frames and is the successor to iptables. The nftables service can be disabled with the following command:

systemctl disable nftables

Rationale:

Running both firewalld and nftables may lead to conflict. nftables is actually one of the backends for firewalld management tools.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_service_nftables_disabled

References:

pcidss4	1.2.1, 1.2

Remediation Puppet snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	enable

include disable_nftables

class disable_nftables {
  service {'nftables':
    enable => false,
    ensure => 'stopped',
  }
}

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - PCI-DSSv4-1.2
  - PCI-DSSv4-1.2.1
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_nftables_disabled

- name: Verify nftables Service is Disabled - Collect systemd Services Present in
    the System
  ansible.builtin.command: systemctl -q list-unit-files --type service
  register: service_exists
  changed_when: false
  failed_when: service_exists.rc not in [0, 1]
  check_mode: false
  when: ( "firewalld" in ansible_facts.packages and "nftables" in ansible_facts.packages
    and "kernel" in ansible_facts.packages )
  tags:
  - PCI-DSSv4-1.2
  - PCI-DSSv4-1.2.1
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_nftables_disabled

- name: Verify nftables Service is Disabled - Ensure nftables.service is Masked
  ansible.builtin.systemd:
    name: nftables.service
    state: stopped
    enabled: false
    masked: true
  when:
  - ( "firewalld" in ansible_facts.packages and "nftables" in ansible_facts.packages
    and "kernel" in ansible_facts.packages )
  - service_exists.stdout_lines is search("nftables.service", multiline=True)
  tags:
  - PCI-DSSv4-1.2
  - PCI-DSSv4-1.2.1
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_nftables_disabled

- name: Unit Socket Exists - nftables.socket
  ansible.builtin.command: systemctl -q list-unit-files nftables.socket
  register: socket_file_exists
  changed_when: false
  failed_when: socket_file_exists.rc not in [0, 1]
  check_mode: false
  when: ( "firewalld" in ansible_facts.packages and "nftables" in ansible_facts.packages
    and "kernel" in ansible_facts.packages )
  tags:
  - PCI-DSSv4-1.2
  - PCI-DSSv4-1.2.1
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_nftables_disabled

- name: Verify nftables Service is Disabled - Disable Socket nftables
  ansible.builtin.systemd:
    name: nftables.socket
    enabled: false
    state: stopped
    masked: true
  when:
  - ( "firewalld" in ansible_facts.packages and "nftables" in ansible_facts.packages
    and "kernel" in ansible_facts.packages )
  - socket_file_exists.stdout_lines is search("nftables.socket", multiline=True)
  tags:
  - PCI-DSSv4-1.2
  - PCI-DSSv4-1.2.1
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_nftables_disabled

Remediation script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	disable


service disable nftables

Remediation OSBuild Blueprint snippet ⇲


[customizations.services]
masked = ["nftables"]

Remediation Kubernetes snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    systemd:
      units:
      - name: nftables.service
        enabled: false
        mask: true
      - name: nftables.socket
        enabled: false
        mask: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	low
Reboot:	false
Strategy:	disable

# Remediation is applicable only in certain platforms
if ( rpm --quiet -q firewalld && rpm --quiet -q nftables && rpm --quiet -q kernel ); then

SYSTEMCTL_EXEC='/usr/bin/systemctl'
"$SYSTEMCTL_EXEC" stop 'nftables.service'
"$SYSTEMCTL_EXEC" disable 'nftables.service'
"$SYSTEMCTL_EXEC" mask 'nftables.service'
# Disable socket activation if we have a unit file for it
if "$SYSTEMCTL_EXEC" -q list-unit-files nftables.socket; then
    "$SYSTEMCTL_EXEC" stop 'nftables.socket'
    "$SYSTEMCTL_EXEC" mask 'nftables.socket'
fi
# The service may not be running because it has been started and failed,
# so let's reset the state so OVAL checks pass.
# Service should be 'inactive', not 'failed' after reboot though.
"$SYSTEMCTL_EXEC" reset-failed 'nftables.service' || true

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Group Uncommon Network Protocols Group contains 2 rules

[ref] The system includes support for several network protocols which are not commonly used. Although security vulnerabilities in kernel networking code are not frequently discovered, the consequences can be dramatic. Ensuring uncommon network protocols are disabled reduces the system's risk to attacks targeted at its implementation of those protocols.

Warning: Although these protocols are not commonly used, avoid disruption in your network environment by ensuring they are not needed prior to disabling them.

Rule Disable DCCP Support [ref]

The Datagram Congestion Control Protocol (DCCP) is a relatively new transport layer protocol, designed to support streaming media and telephony. To configure the system to prevent the dccp kernel module from being loaded, add the following line to the file /etc/modprobe.d/dccp.conf:

install dccp /bin/false

Rationale:

Disabling DCCP protects the system against exploitation of any flaws in its implementation.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_kernel_module_dccp_disabled

References:

cis-csc	11, 14, 3, 9
cjis	5.10.1
cobit5	BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS05.02, DSS05.05, DSS06.06
cui	3.4.6
disa	CCI-001958
isa-62443-2009	4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3
isa-62443-2013	SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 7.6
iso27001-2013	A.12.1.2, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4, A.9.1.2
nist	CM-7(a), CM-7(b), CM-6(a)
nist-csf	PR.IP-1, PR.PT-3
pcidss	Req-1.4.2
os-srg	SRG-OS-000096-GPOS-00050, SRG-OS-000378-GPOS-00163
pcidss4	1.4.2, 1.4

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.10.1
  - NIST-800-171-3.4.6
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - PCI-DSS-Req-1.4.2
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - kernel_module_dccp_disabled
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required

- name: Ensure kernel module 'dccp' is disabled
  lineinfile:
    create: true
    dest: /etc/modprobe.d/dccp.conf
    regexp: install\s+dccp
    line: install dccp /bin/false
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1
  - NIST-800-171-3.4.6
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - PCI-DSS-Req-1.4.2
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - kernel_module_dccp_disabled
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required

Remediation Kubernetes snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,install%20dccp%20/bin/false%0Ablacklist%20dccp%0A
        mode: 0644
        path: /etc/modprobe.d/dccp.conf
        overwrite: true

Remediation Shell script ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

if LC_ALL=C grep -q -m 1 "^install dccp" /etc/modprobe.d/dccp.conf ; then
	
	sed -i 's#^install dccp.*#install dccp /bin/false#g' /etc/modprobe.d/dccp.conf
else
	echo -e "\n# Disable per security requirements" >> /etc/modprobe.d/dccp.conf
	echo "install dccp /bin/false" >> /etc/modprobe.d/dccp.conf
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Rule Disable SCTP Support [ref]

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/false

Rationale:

Disabling SCTP protects the system against exploitation of any flaws in its implementation.

Severity:

medium

Rule ID: xccdf_org.ssgproject.content_rule_kernel_module_sctp_disabled

References:

cis-csc	11, 14, 3, 9
cjis	5.10.1
cobit5	BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS05.02, DSS05.05, DSS06.06
cui	3.4.6
disa	CCI-000381
isa-62443-2009	4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3
isa-62443-2013	SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 7.6
iso27001-2013	A.12.1.2, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4, A.9.1.2
nist	CM-7(a), CM-7(b), CM-6(a)
nist-csf	PR.IP-1, PR.PT-3
pcidss	Req-1.4.2
os-srg	SRG-OS-000095-GPOS-00049, SRG-OS-000480-GPOS-00227
pcidss4	1.4.2, 1.4

Remediation Ansible snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.10.1
  - NIST-800-171-3.4.6
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - PCI-DSS-Req-1.4.2
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - kernel_module_sctp_disabled
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required

- name: Ensure kernel module 'sctp' is disabled
  lineinfile:
    create: true
    dest: /etc/modprobe.d/sctp.conf
    regexp: install\s+sctp
    line: install sctp /bin/false
  when: '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.10.1
  - NIST-800-171-3.4.6
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - PCI-DSS-Req-1.4.2
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - kernel_module_sctp_disabled
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required

Remediation Kubernetes snippet ⇲

Complexity:	low
Disruption:	medium
Reboot:	true
Strategy:	disable

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,install%20sctp%20/bin/false%0Ablacklist%20sctp%0A
        mode: 0644
        path: /etc/modprobe.d/sctp.conf
        overwrite: true

Remediation Shell script ⇲

Disruption:
Complexity:	low