Verify User Who Owns /var/log/localmessages File

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Description

To properly set the owner of /var/log/localmessages, run the command:

$ sudo chown syslog /var/log/localmessages

or

$ sudo chown root /var/log/localmessages

Rationale

The /var/log/localmessages file contains log messages from certain boot scripts, including the DHCP client, and should only be accessed by authorized personnel.

Remediation

Shell script

The following script can be run on the host to remediate the issue.

#!/bin/bash

if id "syslog" >/dev/null 2>&1; then
  newown="syslog"
elif id "root" >/dev/null 2>&1; then
  newown="root"
fi
if [[ -z ${newown} ]]; then
  echo "syslog and root is not a defined user on the system"
  exit 1
fi

find -L /var/log/ -maxdepth 1 -type f  ! -user syslog ! -user root -regextype posix-extended -regex '.*localmessages.*' -exec chown -L $newown {} \;

Ansible playbook

The following playbook can be run with Ansible to remediate the issue.

- name: Check that the syslog user is defined
  getent:
    database: passwd
    key: syslog
  ignore_errors: true
  tags:
  - configure_strategy
  - file_owner_var_log_localmessages
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Set the file_owner_var_log_localmessages_newown variable if syslog found
  set_fact:
    file_owner_var_log_localmessages_newown: syslog
  when: ansible_facts.getent_passwd["syslog"] is defined
  tags:
  - configure_strategy
  - file_owner_var_log_localmessages
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Check that the root user is defined
  getent:
    database: passwd
    key: root
  ignore_errors: true
  when: file_owner_var_log_localmessages_newown is undefined
  tags:
  - configure_strategy
  - file_owner_var_log_localmessages
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Set the file_owner_var_log_localmessages_newown variable if root found
  set_fact:
    file_owner_var_log_localmessages_newown: root
  when: ansible_facts.getent_passwd["root"] is defined
  tags:
  - configure_strategy
  - file_owner_var_log_localmessages
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Find /var/log/ file(s) matching .*localmessages.*
  command: find -L /var/log/ -maxdepth 1 -type f  ! -user syslog ! -user root -regextype
    posix-extended -regex ".*localmessages.*"
  register: files_found
  changed_when: false
  failed_when: false
  check_mode: false
  tags:
  - configure_strategy
  - file_owner_var_log_localmessages
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure owner on /var/log/ file(s) matching .*localmessages.*
  file:
    path: '{{ item }}'
    owner: '{{ file_owner_var_log_localmessages_newown }}'
    state: file
  with_items:
  - '{{ files_found.stdout_lines }}'
  tags:
  - configure_strategy
  - file_owner_var_log_localmessages
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed