---
title: Verify Group Who Owns /var/log/(b|w)tmp(.*|-*) File
description: Datadog, the leading service for cloud-scale monitoring.
breadcrumbs: >-
  Docs > Datadog Security > OOTB Rules > Verify Group Who Owns
  /var/log/(b|w)tmp(.*|-*) File
---

# Verify Group Who Owns /var/log/(b|w)tmp(.*|-*) File
 
## Description{% #description %}

To properly set the group owner of `/var/log/(b|w)tmp(.*|-*)`, run the command:

```gdscript3
$ sudo chgrp utmp /var/log/(b|w)tmp(.*|-*)
```

or

```gdscript3
$ sudo chgrp root /var/log/(b|w)tmp(.*|-*)
```

## Rationale{% #rationale %}

The `/var/log/(b|w)tmp(.*|-*)` file contains logs of reports the most recent login of all users and should only be accessed by authorized personnel.

## Remediation{% #remediation %}

### Shell script{% #shell-script %}

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

```bash
#!/bin/bash

newgroup=""
if getent group "utmp" >/dev/null 2>&1; then
  newgroup="utmp"
elif getent group "root" >/dev/null 2>&1; then
  newgroup="root"
fi

if [[ -z "${newgroup}" ]]; then
  >&2 echo "utmp and root is not a defined group on the system"
else
find -P /var/log/ -maxdepth 1 -type f  ! -group utmp ! -group root -regextype posix-extended -regex '.*(b|w)tmp((\.|-)[^\/]+)?' -exec chgrp --no-dereference "$newgroup" {} \;

fi
```

### Ansible playbook{% #ansible-playbook %}

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

```gdscript3
- name: Check that the utmp group is defined
  ansible.builtin.getent:
    database: group
    key: utmp
  ignore_errors: true
  when: file_groupowner_var_log_wbtmp_newgroup is undefined
  tags:
  - configure_strategy
  - file_groupowner_var_log_wbtmp
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Set the file_groupowner_var_log_wbtmp_newgroup variable if utmp found
  ansible.builtin.set_fact:
    file_groupowner_var_log_wbtmp_newgroup: utmp
  when: ansible_facts.getent_group["utmp"] is defined
  tags:
  - configure_strategy
  - file_groupowner_var_log_wbtmp
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Check that the root group is defined
  ansible.builtin.getent:
    database: group
    key: root
  ignore_errors: true
  when: file_groupowner_var_log_wbtmp_newgroup is undefined
  tags:
  - configure_strategy
  - file_groupowner_var_log_wbtmp
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Set the file_groupowner_var_log_wbtmp_newgroup variable if root found
  ansible.builtin.set_fact:
    file_groupowner_var_log_wbtmp_newgroup: root
  when: ansible_facts.getent_group["root"] is defined
  tags:
  - configure_strategy
  - file_groupowner_var_log_wbtmp
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Find /var/log/ file(s) matching .*(b|w)tmp((\.|-)[^\/]+)?
  ansible.builtin.command: find -P /var/log/ -maxdepth 1 -type f  ! -group utmp !
    -group root -regextype posix-extended -regex ".*(b|w)tmp((\.|-)[^\/]+)?"
  register: files_found
  changed_when: false
  failed_when: false
  check_mode: false
  tags:
  - configure_strategy
  - file_groupowner_var_log_wbtmp
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure group owner on /var/log/ file(s) matching .*(b|w)tmp((\.|-)[^\/]+)?
  ansible.builtin.file:
    path: '{{ item }}'
    follow: false
    group: '{{ file_groupowner_var_log_wbtmp_newgroup }}'
    state: file
  with_items:
  - '{{ files_found.stdout_lines }}'
  tags:
  - configure_strategy
  - file_groupowner_var_log_wbtmp
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
```