Ensure PAM Enforces Password Requirements - Authentication Retry Prompts Permitted Per-Session

An XCCDF Rule

Description

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=, 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.

ID: xccdf_org.ssgproject.content_rule_accounts_password_pam_retry
Severity: Medium
References: 1 11 12 15 16 3 5 9

5.5.3

BAI10.01 BAI10.02 BAI10.03 BAI10.05 DSS05.04 DSS05.05 DSS05.07 DSS05.10 DSS06.03 DSS06.10

CCI-000192 CCI-000366

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

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

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

AC-7(a) CM-6(a) IA-5(4)

PR.AC-1 PR.AC-6 PR.AC-7 PR.IP-1

FMT_MOF_EXT.1

SRG-OS-000069-GPOS-00037 SRG-OS-000480-GPOS-00227

RHEL-07-010119

5.4.1

SV-204406r902704_rule

CCE-27160-1
Updated: about 1 year ago

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

var_password_pam_retry='<xccdf-1.2:sub xmlns:xccdf-1.2="http://checklists.nist.gov/xccdf/1.2" idref="xccdf_org.ssgproject.content_value_var_password_pam_retry" use="legacy"/>'


	
		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=$(grep -nP "^\s*account" "$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

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CCE-27160-1
  - CJIS-5.5.3  - DISA-STIG-RHEL-07-010119
  - 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 <xccdf-1.2:sub xmlns:xccdf-1.2="http://checklists.nist.gov/xccdf/1.2" idref="xccdf_org.ssgproject.content_value_var_password_pam_retry" use="legacy"/>
  tags:
    - always

- 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+{{ 'requisite' | 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:
  - CCE-27160-1
  - CJIS-5.5.3
  - DISA-STIG-RHEL-07-010119
  - 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: \1requisite \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    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 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:
  - CCE-27160-1
  - CJIS-5.5.3
  - DISA-STIG-RHEL-07-010119
  - 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+{{ 'requisite' | regex_escape() }}\s+pam_pwquality.so\s*.*\sretry\b
    state: absent
  check_mode: true
  changed_when: false
  register: result_pam_module_retry_option_present
  when: '"pam" in ansible_facts.packages'
  tags:
  - CCE-27160-1
  - CJIS-5.5.3
  - DISA-STIG-RHEL-07-010119
  - 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+{{ 'requisite' | regex_escape() }}\s+pam_pwquality.so.*)
    line: \1 retry={{ var_password_pam_retry }}
    state: present
  register: result_pam_retry_add
  when:
  - '"pam" in ansible_facts.packages'
  - result_pam_module_retry_option_present.found == 0
  tags:
  - CCE-27160-1
  - CJIS-5.5.3
  - DISA-STIG-RHEL-07-010119
  - 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+{{ 'requisite' | regex_escape() }}\s+pam_pwquality.so\s+.*)(retry)=[0-9a-zA-Z]+\s*(.*)
    line: \1\2={{ var_password_pam_retry }} \3
  register: result_pam_retry_edit
  when:
  - '"pam" in ansible_facts.packages'
  - result_pam_module_retry_option_present.found > 0
  tags:
  - CCE-27160-1
  - CJIS-5.5.3
  - DISA-STIG-RHEL-07-010119
  - 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

Ensure PAM Enforces Password Requirements - Authentication Retry Prompts Permitted Per-Session

Description

Rationale

Remediation - Shell Script

Remediation - Ansible