# Cis Ubuntu1604 V200 5 4 3

> Ensure password reuse is limited

- Skill: `cyberstrikeus/cis-ubuntu1604-v200-5-4-3` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-ubuntu1604-v200-5-4-3`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-ubuntu1604-v200-5-4-3/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- 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-v200-5-4-3

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# Ensure password reuse is limited

**Profile Applicability:**

- Level 1 - Server
- Level 1 - Workstation

**Assessment Status:** Automated

## Description

The `/etc/security/opasswd` file stores the users' old passwords and can be checked to ensure that users are not recycling recent passwords.

## Rationale

Forcing users not to reuse their past 5 passwords make it less likely that an attacker will be able to guess the password.

## Audit Procedure

### Command Line

Run the following commands and ensure the `remember` option is '5' or more and included in all results:

```bash
grep -E '^\s*password\s+required\s+pam_pwhistory\.so\s+([^#]+\s+)?remember=([5-9]|[1-9][0-9]+)\b' /etc/pam.d/common-password
```

**Expected output:**

```
password required pam_pwhistory.so remember=5
```

## Remediation

### Command Line

Edit the `/etc/pam.d/common-password` file to include the `remember` option and conform to site policy as shown:

```
password required pam_pwhistory.so remember=5
```

## Additional Information

Changes only apply to accounts configured on the local system.

## References

None

## CIS Controls

| Controls Version | Control                                                            |
| ---------------- | ------------------------------------------------------------------ |
| v7               | 16 Account Monitoring and Control - Account Monitoring and Control |

## Profile

- **Level 1 - Server**
- **Level 1 - Workstation**