# Cis Ubuntu2004 V300 1 7 1

> Ensure GDM is removed

- Skill: `cyberstrikeus/cis-ubuntu2004-v300-1-7-1` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-ubuntu2004-v300-1-7-1`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-ubuntu2004-v300-1-7-1/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-ubuntu2004-v300-1-7-1

---


# 1.7.1 Ensure GDM is removed (Automated)

## Profile

- Level 2 - Server

## Description

The GNOME Display Manager (GDM) is a program that manages graphical display servers and handles graphical user logins.

## Rationale

If a Graphical User Interface (GUI) is not required, it should be removed to reduce the attack surface of the system.

## Impact

Removing the GNOME Display manager will remove the Graphical User Interface (GUI) from the system.

## Audit Procedure

### Command Line

Run the following command and verify `gdm3` is not installed:

```bash
# dpkg-query -s gdm3 &>/dev/null && echo "gdm3 is installed"
```

Nothing should be returned.

## Expected Result

No output should be returned, confirming gdm3 is not installed.

## Remediation

### Command Line

Run the following commands to uninstall `gdm3` and remove unused dependencies:

```bash
# apt purge gdm3
# apt autoremove gdm3
```

## References

1. NIST SP 800-53 Rev. 5: CM-11

## CIS Controls

| Controls Version | Control                                                                         | IG 1 | IG 2 | IG 3 |
| ---------------- | ------------------------------------------------------------------------------- | ---- | ---- | ---- |
| v8               | 4.8 Uninstall or Disable Unnecessary Services on Enterprise Assets and Software |      | \*   | \*   |
| v7               | 9.2 Ensure Only Approved Ports, Protocols and Services Are Running              |      | \*   | \*   |

MITRE ATT&CK Mappings: T1543, T1543.002 | TA0002 | M1033