# Cis Ubuntu2004 V300 1 4 2

> Ensure access to bootloader config is configured

- Skill: `cyberstrikeus/cis-ubuntu2004-v300-1-4-2` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-ubuntu2004-v300-1-4-2`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-ubuntu2004-v300-1-4-2/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-ubuntu2004-v300-1-4-2

---


# 1.4.2 Ensure access to bootloader config is configured (Automated)

## Profile

- 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 -Lc 'Access: (%#a/%A) Uid: ( %u/ %U) Gid: ( %g/ %G)' /boot/grub/grub.cfg
```

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

## Expected Result

Access should be `0600` or more restrictive, Uid and Gid should both be `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
```

## Default Value

Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)

## References

1. NIST SP 800-53 Rev. 5: AC-3

## 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.

## CIS Controls

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

MITRE ATT&CK Mappings: T1542, T1542.000 | TA0005, TA0007 | M1022