# Cis Ubuntu1804 V220 4 3 2

> Ensure sudo commands use pty

- Skill: `cyberstrikeus/cis-ubuntu1804-v220-4-3-2` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-ubuntu1804-v220-4-3-2`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-ubuntu1804-v220-4-3-2/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-ubuntu1804-v220-4-3-2

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# CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0 - Control 4.3.2

## Profile Applicability

- Level 1 - Server
- Level 1 - Workstation

## Description

`sudo` can be configured to run only from a pseudo terminal (pseudo-pty).

## Rationale

Attackers can run a malicious program using `sudo` which forks a background process that remains on the user's terminal device even after the main program has finished executing. This can be used to intercept user input including passwords. By configuring `sudo` to use a pseudo terminal, this attack is no longer possible.

## Audit Procedure

### Command Line

Run the following command to verify that `sudo` uses a pseudo terminal:

```bash
grep -rPi '^\h*Defaults\h+([^#\n\r]+,)?use_pty(,\h*\h+\h*)*\h*(#.*)?$' /etc/sudoers /etc/sudoers.d/
```

### Expected Result

```
Defaults use_pty
```

## Remediation

### Command Line

Edit the file `/etc/sudoers` or a file in `/etc/sudoers.d/` with `visudo` and add the following line:

```bash
Defaults use_pty
```

## References

1. NIST SP 800-53 Rev. 5: AC-6(1)

## CIS Controls

v8 - 5.4 Restrict Administrator Privileges to Dedicated Administrator Accounts.

v7 - 4.3 Ensure the Use of Dedicated Administrative Accounts.

## Profile Applicability

- Level 1 - Server
- Level 1 - Workstation

## Assessment Status

Automated