# Cis GCP Cos 6.2.20

> Ensure shadow group is empty

- Skill: `cyberstrikeus/cis-gcp-cos-6-2-20` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-gcp-cos-6-2-20`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-gcp-cos-6-2-20/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-6-2-20

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# 6.2.20 Ensure shadow group is empty (Automated)

## Description

The shadow group allows system programs which require access the ability to read the /etc/shadow file. No users should be assigned to the shadow group.

## Rationale

Any users assigned to the shadow group would be granted read access to the /etc/shadow file. If attackers can gain read access to the `/etc/shadow` file, they can easily run a password cracking program against the hashed passwords to break them. Other security information that is stored in the `/etc/shadow` file (such as expiration) could also be useful to subvert additional user accounts.

## Audit Procedure

Run the following commands and verify no results are returned:

```bash
# grep ^shadow:[^:]*:[^:]*:[^:]+ /etc/group
# awk -F: '($4 == "<shadow-gid>") { print }' /etc/passwd
```

## Expected Result

No results should be returned.

## Remediation

Remove all users from the shadow group, and change the primary group of any users with shadow as their primary group.

## CIS Controls

| Controls Version | Control                             | IG 1 | IG 2 | IG 3 |
| ---------------- | ----------------------------------- | ---- | ---- | ---- |
| v7               | 5.1 Establish Secure Configurations | x    | x    | x    |

## Profile

- Level 1 - Server