cis-ubuntu2004-v300-1-1-1-5

name	cis-ubuntu2004-v300-1-1-1-5
description	Ensure jffs2 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	1.1.1.5
cis_benchmark	CIS Ubuntu Linux 20.04 LTS Benchmark v3.0.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

Ensure jffs2 kernel module is not available

Profile

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

Description

The jffs2 (journaling flash filesystem 2) filesystem type is a log-structured filesystem used in flash memory devices.

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 jffs2 kernel module is not available on the system - OR - has been disabled.

Run the following script to determine if the jffs2 kernel module is available on the system:

#!/usr/bin/env bash

{
   l_mod_name="jffs2" 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 jffs2 kernel module is not available on the system and no further audit steps are required.

Note: Some systems may include the jffs2 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 jffs2 kernel module is not loaded and not loadable by performing the following: