Ensure PAM password complexity module is enabled in system-auth
An XCCDF Rule
Description
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.
- ID
- xccdf_org.ssgproject.content_rule_accounts_password_pam_pwquality_system_auth
- Severity
- Medium
- References
- CCI: Control Correlation IdentifierGPOS SRG: General Purpose Operating System Security Requirements GuideCCE: Common Configuration Enumeration
- Updated
Remediation - Ansible
- name: Gather the package facts
package_facts:
manager: auto
tags:
- CCE-85874-6
- 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:
- CCE-85874-6
- 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 - Check
if expected PAM module line is present in {{ pam_file_path }}
ansible.builtin.lineinfile:
path: '{{ pam_file_path }}'
regexp: ^\s*password\s+{{ 'requisite' | 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: \1requisite \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 requisite 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__add is defined and result_pam__add.changed)
or (result_pam__edit is defined and result_pam__edit.changed)
when:
- '"pam" in ansible_facts.packages'
- result_pam_file_present.stat.exists
tags:
- CCE-85874-6
- 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*' "$PAM_FILE_PATH")" -eq 1 ]; then
# The control is updated only if one single line matches.
sed -i -E --follow-symlinks 's/^(\s*password\s+).*(\bpam_pwquality.so.*)/\1'"requisite"' \2/' "$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