# Cis Ubuntu1804 V220 6 1 4

> Ensure permissions on /etc/group- are configured

- Skill: `cyberstrikeus/cis-ubuntu1804-v220-6-1-4` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-ubuntu1804-v220-6-1-4`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-ubuntu1804-v220-6-1-4/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: cyberstrikeus (https://skillmd.com/u/cyberstrikeus)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/cyberstrikeus/cis-ubuntu1804-v220-6-1-4

---


# 6.1.4 Ensure permissions on /etc/group- are configured (Automated)

## Profile

- Level 1 - Server
- Level 1 - Workstation

## Description

The `/etc/group-` file contains a backup list of all the valid groups defined in the system.

## Rationale

It is critical to ensure that the `/etc/group-` file is protected from unauthorized access. Although it is protected by default, the file permissions could be changed either inadvertently or through malicious actions.

## Audit Procedure

### Command Line

Run the following command to verify `/etc/group-` is mode 644 or more restrictive, `Uid` is `0/root` and `Gid` is `0/root`:

```bash
# stat -Lc 'Access: (%#a/%A) Uid: ( %u/ %U) Gid: ( %g/ %G)' /etc/group-
```

## Expected Result

```
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
```

## Remediation

### Command Line

Run the following commands to remove excess permissions, set owner, and set group on `/etc/group-`:

```bash
# chmod u-x,go-wx /etc/group-
# chown root:root /etc/group-
```

## Default Value

Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)

## References

1. NIST SP 800-53 Rev. 5: AC-3. MP-2

## CIS Controls

- v8: **3.3** Configure Data Access Control Lists
- v7: **14.6** Protect Information through Access Control Lists