# Cis GCP Cos 6.1.2

> Ensure permissions on /etc/shadow are configured

- Skill: `cyberstrikeus/cis-gcp-cos-6-1-2` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-gcp-cos-6-1-2`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-gcp-cos-6-1-2/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-6-1-2

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# 6.1.2 Ensure permissions on /etc/shadow are configured (Automated)

## Description

The `/etc/shadow` file is used to store the information about user accounts that is critical to the security of those accounts, such as the hashed password and other security information.

## Rationale

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

## Audit Procedure

Run the following command and verify verify `Uid` is `0/root`, `Gid` is `0/root` or `<gid>/shadow`, and `Access` is `640` or more restrictive:

```bash
# stat /etc/shadow
Access: (0640/-rw-r-----)  Uid: (    0/    root)   Gid: (    0/    root)
```

## Expected Result

`Uid` should be `0/root`, `Gid` should be `0/root` or `<gid>/shadow`, and `Access` should be `640` or more restrictive.

## Remediation

Run the one of the following chown commands as appropriate and the chmod to set permissions on `/etc/shadow`:

```bash
# chown root:root /etc/shadow
# chown root:shadow /etc/shadow

# chmod o-rwx,g-wx /etc/shadow
```

## CIS Controls

| Controls Version | Control                                             | IG 1 | IG 2 | IG 3 |
| ---------------- | --------------------------------------------------- | ---- | ---- | ---- |
| v8               | 3.3 Configure Data Access Control Lists             | x    | x    | x    |
| v7               | 16.4 Encrypt or Hash all Authentication Credentials |      | x    | x    |

## Profile

- Level 1 - Server