# Cis Ubuntu1804 V220 1 8 1

> Ensure GNOME Display Manager is removed

- Skill: `cyberstrikeus/cis-ubuntu1804-v220-1-8-1` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-ubuntu1804-v220-1-8-1`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-ubuntu1804-v220-1-8-1/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-ubuntu1804-v220-1-8-1

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# 1.8.1 Ensure GNOME Display Manager is removed (Automated)

## Profile Applicability

- 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"
```

## Expected Result

Nothing should be returned.

## Remediation

### Command Line

Run the following command to uninstall `gdm3`:

```bash
apt purge 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 |      | X    | X    |
| v7               | 9.2 Ensure Only Approved Ports, Protocols and Services Are Running              |      | X    | X    |

## MITRE ATT&CK Mappings

| Techniques / Sub-techniques | Tactics | Mitigations |
| --------------------------- | ------- | ----------- |
| T1543, T1543.002            | TA0002  | M1033       |