# Cis Ubuntu1604 V200 1 1 1 1

> Ensure mounting of cramfs filesystems is disabled

- Skill: `cyberstrikeus/cis-ubuntu1604-v200-1-1-1-1` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-ubuntu1604-v200-1-1-1-1`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-ubuntu1604-v200-1-1-1-1/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-ubuntu1604-v200-1-1-1-1

---


# Ensure mounting of cramfs filesystems is disabled

## Description

The cramfs filesystem type is a compressed read-only Linux filesystem embedded in small footprint systems. A cramfs image can be used without having to first decompress the image.

## Rationale

Removing support for unneeded filesystem types reduces the local attack surface of the server. If this filesystem type is not needed, disable it.

## Impact

None noted.

## Audit Procedure

### Command Line

```bash
# modprobe -n -v cramfs | grep -E '(cramfs|install)'
# lsmod | grep cramfs
```

## Expected Result

```
install /bin/true
```

The `lsmod` command should return no output.

## Remediation

### Command Line

```bash
# Edit or create a file in the /etc/modprobe.d/ directory ending in .conf
# Example: vim /etc/modprobe.d/cramfs.conf
# and add the following line:
install cramfs /bin/true

# Run the following command to unload the cramfs module:
rmmod cramfs
```

## Default Value

Not disabled by default.

## References

- CIS Controls Version 7 - 5.1 Establish Secure Configurations: Maintain documented, standard security configuration standards for all authorized operating systems and software.

## Profile

Level 1 - Server / Level 1 - Workstation, Assessment: Automated