# Cis Ubuntu1604 V200 6 1 3

> Ensure permissions on /etc/passwd- are configured

- Skill: `cyberstrikeus/cis-ubuntu1604-v200-6-1-3` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-ubuntu1604-v200-6-1-3`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-ubuntu1604-v200-6-1-3/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector CAUTION)
- 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-ubuntu1604-v200-6-1-3

---


# CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0 - 6.1.3

## Profile Applicability

- Level 1 - Server
- Level 1 - Workstation

## Description

The `/etc/passwd-` file contains backup user account information.

## Rationale

It is critical to ensure that the `/etc/passwd-` file is protected from unauthorized access. Although it is protected by default, the file permissions could be changed either inadvertently or through malicious actions.

## Audit Procedure

### Command Line

Run the following command and verify `Uid` and `Gid` are both `0/root` and `Access` is `644` or more restrictive:

```bash
stat /etc/passwd-
```

## Expected Result

```
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
```

## Remediation

### Command Line

Run the following command to set permissions on `/etc/passwd-`:

```bash
chown root:root /etc/passwd-
chmod u-x,go-wx /etc/passwd-
```

## Default Value

Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)

## References

1. CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0

## CIS Controls

| Controls Version | Control                                                                                                                        |
| ---------------- | ------------------------------------------------------------------------------------------------------------------------------ |
| v7               | 16.4 Encrypt or Hash all Authentication Credentials<br>Encrypt or hash with a salt all authentication credentials when stored. |

## Assessment Status

Automated