Cis Ubuntu2004 V300 5 3 3 1 2

---
name: cis-ubuntu2004-v300-5-3-3-1-2
description: "Ensure password unlock time is configured"
category: cis-iam
version: "3.0.0"
author: cyberstrike-official
tags: [cis, ubuntu, linux, ubuntu-20.04, pam, authentication]
cis_id: "5.3.3.1.2"
cis_benchmark: "CIS Ubuntu Linux 20.04 LTS Benchmark v3.0.0"
tech_stack: [ubuntu, linux]
cwe_ids: []
chains_with: []
prerequisites: []
severity_boost: {}
---

# 5.3.3.1.2 Ensure password unlock time is configured (Automated)

## Profile Applicability

- Level 1 - Server
- Level 1 - Workstation

## Description

`unlock_time=<n>` - The access will be re-enabled after seconds after the lock out. The value `0` has the same meaning as value never - the access will not be re-enabled without resetting the faillock entries by the faillock(8) command.

Note:

- The default directory that pam_faillock uses is usually cleared on system boot so the access will be also re-enabled after system reboot. If that is undesirable a different tally directory must be set with the dir option.
- It is usually undesirable to permanently lock out users as they can become easily a target of denial of service attack unless the usernames are random and kept secret to potential attackers.
- The maximum configurable value for `unlock_time` is `604800`.

## Rationale

Locking out user IDs after n unsuccessful consecutive login attempts mitigates brute force password attacks against your systems.

## Impact

Use of `unlock_time=0` may allow an attacker to cause denial of service to legitimate users. This will also require a systems administrator with elevated privileges to unlock the account.

## Audit Procedure

### Command Line

Run the following command to verify that the time in seconds before the account is unlocked is either `0` (never) or `900` (15 minutes) or more and meets local site policy:

```bash
# grep -Pi -- '^\h*unlock_time\h*=\h*(0|9[0-9][0-9]|[1-9][0-9]{3,})\b' /etc/security/faillock.conf
```

Expected output:

```
unlock_time = 900
```

Run the following command to verify that the `unlock_time` argument has not been set, or is either `0` (never) or `900` (15 minutes) or more and meets local site policy:

```bash
# grep -Pi -- '^\h*auth\h+(requisite|required|sufficient)\h+pam_faillock\.so\h+([^#\n\r]+\h+)?unlock_time\h*=\h*([1-9]|[1-9][0-9]|[1-8][0-9][0-9])\b' /etc/pam.d/common-auth
```

## Expected Result

Nothing should be returned from the second command.

## Remediation

### Command Line

Set password unlock time to conform to site policy. `unlock_time` should be `0` (never), or `900` seconds or greater.
Edit `/etc/security/faillock.conf` and update or add the following line:

```
unlock_time = 900
```

Run the following command: remove the `unlock_time` argument from the `pam_faillock.so` module in the PAM files:

```bash
# grep -Pl -- '\bpam_faillock\.so\h+([^#\n\r]+\h+)?unlock_time\b' /usr/share/pam-configs/*
```

Edit any returned files and remove the `unlock_time=<N>` argument from the `pam_faillock.so` line(s).

## Default Value

unlock_time = 600

## Additional Information

If a user has been locked out because they have reached the maximum consecutive failure count defined by `deny=` in the `pam_faillock.so` module, the user can be unlocked by issuing the command `faillock --user <USERNAME> --reset`. This command sets the failed count to 0, effectively unlocking the user.

## References

None listed.

## CIS Controls

| Controls Version | Control                                    | IG 1 | IG 2 | IG 3 |
| ---------------- | ------------------------------------------ | ---- | ---- | ---- |
| v8               | 6.2 Establish an Access Revoking Process   | \*   | \*   | \*   |
| v7               | 16.7 Establish Process for Revoking Access |      | \*   | \*   |

## MITRE ATT&CK Mappings

| Techniques / Sub-techniques | Tactics | Mitigations |
| --------------------------- | ------- | ----------- |
| T1110, T1110.001, T1110.003 | TA0006  | M1027       |