---
title: Verify Group Ownership on SSH Server Public *.pub Key Files
description: Datadog, the leading service for cloud-scale monitoring.
breadcrumbs: >-
  Docs > Datadog Security > OOTB Rules > Verify Group Ownership on SSH Server
  Public *.pub Key Files
---

> For the complete documentation index, see [llms.txt](https://docs.datadoghq.com/llms.txt).

# Verify Group Ownership on SSH Server Public *.pub Key Files
 
## Description{% #description %}

SSH server public keys, files that match the `/etc/ssh/*.pub` glob, must be group-owned by `root` group.

## Rationale{% #rationale %}

If a public host key file is modified by an unauthorized user, the SSH service may be compromised.

## Remediation{% #remediation %}

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

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

```bash
#!/bin/bash

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

newgroup=""
if getent group "0" >/dev/null 2>&1; then
  newgroup="0"
fi

if [[ -z "${newgroup}" ]]; then
  >&2 echo "0 is not a defined group on the system"
else
find -P /etc/ssh/ -maxdepth 1 -type f  ! -group 0 -regextype posix-extended -regex '^.*\.pub$' -exec chgrp --no-dereference "$newgroup" {} \;

fi

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

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

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

```gdscript3
- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CCE-86133-6
  - configure_strategy
  - file_groupownership_sshd_pub_key
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Set the file_groupownership_sshd_pub_key_newgroup variable if represented
    by gid
  ansible.builtin.set_fact:
    file_groupownership_sshd_pub_key_newgroup: '0'
  when: '"kernel-core" in ansible_facts.packages'
  tags:
  - CCE-86133-6
  - configure_strategy
  - file_groupownership_sshd_pub_key
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Find /etc/ssh/ file(s) matching ^.*\.pub$
  ansible.builtin.command: find -P /etc/ssh/ -maxdepth 1 -type f  ! -group 0 -regextype
    posix-extended -regex "^.*\.pub$"
  register: files_found
  changed_when: false
  failed_when: false
  check_mode: false
  when: '"kernel-core" in ansible_facts.packages'
  tags:
  - CCE-86133-6
  - configure_strategy
  - file_groupownership_sshd_pub_key
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure group owner on /etc/ssh/ file(s) matching ^.*\.pub$
  ansible.builtin.file:
    path: '{{ item }}'
    follow: false
    group: '{{ file_groupownership_sshd_pub_key_newgroup }}'
    state: file
  with_items:
  - '{{ files_found.stdout_lines }}'
  when: '"kernel-core" in ansible_facts.packages'
  tags:
  - CCE-86133-6
  - configure_strategy
  - file_groupownership_sshd_pub_key
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
```

## Warning{% #warning %}

Remediation is not possible at bootable container build time because SSH host keys are generated post-deployment.