Configure System to Forward All Mail From Postmaster to The Root Account

An XCCDF Rule

Description

Verify the administrators are notified in the event of an audit processing failure. Check that the "/etc/aliases" file has a defined value for "root".

$ sudo grep "postmaster:\s*root$" /etc/aliases

postmaster: root

Rationale

It is critical for the appropriate personnel to be aware if a system is at risk of failing to process audit logs as required. Without this notification, the security personnel may be unaware of an impending failure of the audit capability, and system operation may be adversely affected. Audit processing failures include software/hardware errors, failures in the audit capturing mechanisms, and audit storage capacity being reached or exceeded.

ID: xccdf_org.ssgproject.content_rule_postfix_client_configure_mail_alias_postmaster
Severity: Medium
References: CCI-000139

AU-5(a) AU-5.1(ii)

SRG-OS-000046-GPOS-00022
Updated: about 1 year ago

# Remediation is applicable only in certain platforms
if [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; then

if [ -e "/etc/aliases" ] ; then
    
    LC_ALL=C sed -i "/^\s*postmaster\s*:\s*/Id" "/etc/aliases"else
    touch "/etc/aliases"
fi
# make sure file has newline at the end
sed -i -e '$a\' "/etc/aliases"

cp "/etc/aliases" "/etc/aliases.bak"
# Insert at the end of the file
printf '%s\n' "postmaster: root" >> "/etc/aliases"
# Clean up after ourselves.
rm "/etc/aliases.bak"

if [ -f /usr/bin/newaliases ]; then
    newaliases
fi

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

- name: Configure System to Forward All Mail From Postmaster to The Root Account
  block:

  - name: Check for duplicate values
    lineinfile:
      path: /etc/aliases      create: true
      regexp: ^\s*postmaster\s*:\s*
      state: absent
    check_mode: true
    changed_when: false
    register: dupes

  - name: Deduplicate values from /etc/aliases
    lineinfile:
      path: /etc/aliases
      create: true
      regexp: ^\s*postmaster\s*:\s*
      state: absent
    when: dupes.found is defined and dupes.found > 1

  - name: Insert correct line to /etc/aliases
    lineinfile:
      path: /etc/aliases
      create: true
      regexp: ^\s*postmaster\s*:\s*
      line: 'postmaster: root'
      state: present
  when: ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - NIST-800-53-AU-5(a)
  - NIST-800-53-AU-5.1(ii)
  - configure_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - postfix_client_configure_mail_alias_postmaster

- name: Check if newaliases command is available
  ansible.builtin.stat:
    path: /usr/bin/newaliases
  register: result_newaliases_present
  when: ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - NIST-800-53-AU-5(a)
  - NIST-800-53-AU-5.1(ii)
  - configure_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - postfix_client_configure_mail_alias_postmaster

- name: Update postfix aliases
  ansible.builtin.command:
    cmd: newaliases
  when:
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - result_newaliases_present.stat.exists
  tags:
  - NIST-800-53-AU-5(a)
  - NIST-800-53-AU-5.1(ii)
  - configure_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - postfix_client_configure_mail_alias_postmaster

Configure System to Forward All Mail From Postmaster to The Root Account

Description

Rationale

Remediation - Shell Script

Remediation - Ansible