cis-ubuntu2004-v300-1-1-1-3

name	cis-ubuntu2004-v300-1-1-1-3
description	Ensure hfs 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	1.1.1.3
cis_benchmark	CIS Ubuntu Linux 20.04 LTS Benchmark v3.0.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

Ensure hfs kernel module is not available

Profile

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

Description

The hfs filesystem type is a hierarchical filesystem that allows you to mount Mac OS filesystems.

Rationale

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

Audit Procedure

Command Line

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

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

#!/usr/bin/env bash

{
   l_mod_name="hfs" 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 hfs kernel module is not available on the system and no further audit steps are required.

Note: Some systems may include the hfs filesystem as part of the kernel opposed to being available as a kernel module. In this case, the above audit will not return anything. This is also considered a passing state.

If anything is returned, verify the hfs kernel module is not loaded and not loadable by performing the following: