Verify User Who Owns /var/log/messages File

Description

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

$ sudo chown syslog /var/log/messages

or

$ sudo chown root /var/log/messages

Rationale

The /var/log/messages file contains logs of error messages in the system 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
    username="syslog"
else
    username="root"
fi

find -L /var/log/ -maxdepth 1 ! -user root ! -user syslog -type f -regextype posix-extended -name 'messages' -exec chown $username {} \;

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_messages
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

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

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

- name: Test for existence /var/log/messages
  stat:
    path: /var/log/messages
  register: file_exists
  tags:
  - configure_strategy
  - file_owner_var_log_messages
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure owner on /var/log/messages
  file:
    path: /var/log/messages
    owner: '{{ file_owner_var_log_messages_newown }}'
  when: file_exists.stat is defined and file_exists.stat.exists
  tags:
  - configure_strategy
  - file_owner_var_log_messages
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed