# Cis GCP Cos 5.3.1.1

> Ensure password expiration is 365 days or less

- Skill: `cyberstrikeus/cis-gcp-cos-5-3-1-1` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-gcp-cos-5-3-1-1`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-gcp-cos-5-3-1-1/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-5-3-1-1

---


# 5.3.1.1 Ensure password expiration is 365 days or less (Automated)

## Description

The `PASS_MAX_DAYS` parameter in `/etc/login.defs` allows an administrator to force passwords to expire once they reach a defined age. It is recommended that the `PASS_MAX_DAYS` parameter be set to less than or equal to 365 days.

## Rationale

The window of opportunity for an attacker to leverage compromised credentials or successfully compromise credentials via an online brute force attack is limited by the age of the password. Therefore, reducing the maximum age of a password also reduces an attacker's window of opportunity.

## Audit Procedure

Run the following command and verify `PASS_MAX_DAYS` conforms to site policy (no more than 365 days):

```bash
# grep PASS_MAX_DAYS /etc/login.defs

PASS_MAX_DAYS 365
```

Run the following command and Review list of users and PASS_MAX_DAYS to verify that all users' PASS_MAX_DAYS conforms to site policy (no more than 365 days):

```bash
# grep -E '^[^:]+:[^!*]' /etc/shadow | cut -d: -f1,5

<user>:<PASS_MAX_DAYS>
```

## Expected Result

`PASS_MAX_DAYS` should be 365 or less in `/etc/login.defs` and for all users with a password in `/etc/shadow`.

## Remediation

Set the `PASS_MAX_DAYS` parameter to conform to site policy in `/etc/login.defs`:

```
PASS_MAX_DAYS 365
```

Modify user parameters for all users with a password set to match:

```bash
# chage --maxdays 365 <user>
```

Additional Information:

You can also check this setting in `/etc/shadow` directly. The 5th field should be 365 or less for all users with a password.

Note: A value of -1 will disable password expiration. Additionally the password expiration must be greater than the minimum days between password changes or users will be unable to change their password.

## CIS Controls

| Controls Version | Control                                                                                                                                                                                                                                    | IG 1 | IG 2 | IG 3 |
| ---------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ---- | ---- | ---- |
| v8               | **5.2 Use Unique Passwords** - Use unique passwords for all enterprise assets. Best practice implementation includes, at a minimum, an 8-character password for accounts using MFA and a 14-character password for accounts not using MFA. | x    | x    | x    |
| v7               | **4.4 Use Unique Passwords** - Where multi-factor authentication is not supported (such as local administrator, root, or service accounts), accounts will use passwords that are unique to that system.                                    |      | x    | x    |

## Profile

- Level 2 - Server