# Cis Ubuntu1604 V200 1 1 1 6

> Ensure mounting of udf filesystems is disabled

- Skill: `cyberstrikeus/cis-ubuntu1604-v200-1-1-1-6` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-ubuntu1604-v200-1-1-1-6`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-ubuntu1604-v200-1-1-1-6/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-v200-1-1-1-6

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# Ensure mounting of udf filesystems is disabled

## Description

The udf filesystem type is the universal disk format used to implement ISO/IEC 13346 and ECMA-167 specifications. This is an open vendor filesystem type for data storage on a broad range of media. This filesystem type is necessary to support writing DVDs and newer optical disc formats.

## Rationale

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

## Impact

None noted.

## Audit Procedure

### Command Line

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

## 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: vi /etc/modprobe.d/udf.conf
# and add the following line:
install udf /bin/true

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

## 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