cis-ubuntu2004-v300-1-1-1-8

name	cis-ubuntu2004-v300-1-1-1-8
description	Ensure udf kernel module is not available
category	cis-storage
version	3.0.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-20.04","kernel-module"]
cis_id	1.1.1.8
cis_benchmark	CIS Ubuntu Linux 20.04 LTS Benchmark v3.0.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

Ensure udf kernel module is not available

Profile

Level 2 - Server, Level 2 - Workstation, Assessment: Automated

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

Microsoft Azure requires the usage of udf.

udf should not be disabled on systems run on Microsoft Azure.

Audit Procedure

Command Line

Verify the udf kernel module is not available on the system - OR - has been disabled.

Run the following script to determine if the udf kernel module is available on the system:

#!/usr/bin/env bash

{
   l_mod_name="udf" l_mod_type="fs"
   while IFS= read -r l_mod_path; do
      if [ -d "$l_mod_path/${l_mod_name}/-/\/" ] &&  [ -n "$(ls -A "$l_mod_path/${l_mod_name}/-/\/")" ]; then
         printf '%s\n' "$l_mod_name exists in $l_mod_path"
      fi
   done < <(readlink -f /usr/lib/modules/**/kernel/$l_mod_type || readlink -f /lib/modules/**/kernel/$l_mod_type)
}

If nothing is returned, the udf kernel module is not available on the system and no further audit steps are required.