Cis Ubuntu2004 V300 1 7 1

---
name: cis-ubuntu2004-v300-1-7-1
description: "Ensure GDM is removed"
category: cis-networking
version: "3.0.0"
author: cyberstrike-official
tags: [cis, ubuntu, linux, ubuntu-20.04, gnome, gdm, attack-surface]
cis_id: "1.7.1"
cis_benchmark: "CIS Ubuntu Linux 20.04 LTS Benchmark v3.0.0"
tech_stack: [ubuntu, linux]
cwe_ids: []
chains_with: []
prerequisites: []
severity_boost: {}
---

# 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