# Cis GCP Cos 5.3.3

> Ensure default group for the root account is GID 0

- Skill: `cyberstrikeus/cis-gcp-cos-5-3-3` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-gcp-cos-5-3-3`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-gcp-cos-5-3-3/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector CAUTION)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: DevOps & Infra
- Author: cyberstrikeus (https://skillmd.com/u/cyberstrikeus)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/cyberstrikeus/cis-gcp-cos-5-3-3

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# 5.3.3 Ensure default group for the root account is GID 0 (Automated)

## Description

The usermod command can be used to specify which group the root user belongs to. This affects permissions of files that are created by the root user.

## Rationale

Using GID 0 for the `root` account helps prevent `root`-owned files from accidentally becoming accessible to non-privileged users.

## Audit Procedure

Run the following command and verify the result is `0`:

```bash
# grep "^root:" /etc/passwd | cut -f4 -d:
0
```

## Expected Result

The command should return `0`, confirming that root's default group is GID 0.

## Remediation

Run the following command to set the `root` user default group to GID `0`:

```bash
# usermod -g 0 root
```

## CIS Controls

| Controls Version | Control                                                                                                                                                                                                                                             | IG 1 | IG 2 | IG 3 |
| ---------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---- | ---- | ---- |
| v8               | **3.3 Configure Data Access Control Lists** - Configure data access control lists based on a user's need to know. Apply data access control lists, also known as access permissions, to local and remote file systems, databases, and applications. | x    | x    | x    |
| v7               | **5.1 Establish Secure Configurations** - Maintain documented, standard security configuration standards for all authorized operating systems and software.                                                                                         | x    | x    | x    |

## Profile

- Level 1 - Server