# Cis Ubuntu1804 V220 1 4 2

> Ensure permissions on bootloader config are configured

- Skill: `cyberstrikeus/cis-ubuntu1804-v220-1-4-2` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-ubuntu1804-v220-1-4-2`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-ubuntu1804-v220-1-4-2/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-v220-1-4-2

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# 1.4.2 Ensure permissions on bootloader config are configured (Automated)

## Profile Applicability

- Level 1 - Server
- Level 1 - Workstation

## Description

The grub configuration file contains information on boot settings and passwords for unlocking boot options.

## Rationale

Setting the permissions to read and write for root only prevents non-root users from seeing the boot parameters or changing them. Non-root users who read the boot parameters may be able to identify weaknesses in security upon boot and be able to exploit them.

## Audit Procedure

### Command Line

Run the following command and verify `Uid` and `Gid` are both `0/root` and `Access` is `0600` or more restrictive:

```bash
stat /boot/grub/grub.cfg
```

## Expected Result

```
Access: (0600/-r--------) Uid: ( 0/ root) Gid: ( 0/ root)
```

## Remediation

### Command Line

Run the following commands to set permissions on your grub configuration:

```bash
chown root:root /boot/grub/grub.cfg
chmod u-x,go-rwx /boot/grub/grub.cfg
```

## Additional Information

This recommendation is designed around the grub bootloader, if LILO or another bootloader is in use in your environment enact equivalent settings.

Replace `/boot/grub/grub.cfg` with the appropriate grub configuration file for your environment.

## References

1. NIST SP 800-53 Rev. 5: CM-6

## CIS Controls

| Controls Version | Control                                               | IG 1 | IG 2 | IG 3 |
| ---------------- | ----------------------------------------------------- | ---- | ---- | ---- |
| v8               | 3.3 Configure Data Access Control Lists               | X    | X    | X    |
| v7               | 14.6 Protect Information through Access Control Lists | X    | X    | X    |

## MITRE ATT&CK Mappings

| Techniques / Sub-techniques | Tactics        | Mitigations |
| --------------------------- | -------------- | ----------- |
| T1542, T1542.000            | TA0005, TA0007 | M1022       |