cis-ubuntu2004-v300-4-3-2

name	cis-ubuntu2004-v300-4-3-2
description	Ensure ufw is uninstalled or disabled with nftables
category	cis-networking
version	3.0.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-20.04","firewall","nftables"]
cis_id	4.3.2
cis_benchmark	CIS Ubuntu Linux 20.04 LTS Benchmark v3.0.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

CIS Ubuntu Linux 20.04 LTS Benchmark v3.0.0 - Control 4.3.2

Profile

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

Description

Uncomplicated Firewall (UFW) is a program for managing a netfilter firewall designed to be easy to use.

Rationale

Running both the nftables service and ufw may lead to conflict and unexpected results.

Audit Procedure

Command Line

Run the following commands to verify that ufw is either not installed or inactive. Only one of the following needs to pass. Run the following command to verify that ufw is not installed:

dpkg-query -s ufw &>/dev/null && echo "ufw is installed"

Nothing should be returned -OR- Run the following commands to verify ufw is disabled and ufw.service is not enabled:

ufw status

Status: inactive

systemctl is-enabled ufw.service

masked

Expected Result

ufw is not installed, or ufw status is inactive and ufw.service is masked.

Remediation

Command Line

Run one of the following to either remove ufw or disable ufw and mask ufw.service: Run the following command to remove ufw:

apt purge ufw

-OR- Run the following commands to disable ufw and mask ufw.service:

ufw disable
systemctl stop ufw.service
systemctl mask ufw.service

Note: ufw disable needs to be run before systemctl mask ufw.service in order to correctly disable UFW

Default Value

Not applicable.

References

1. NIST SP 800-53 Rev. 5: SC-7

CIS Controls

v8 - 4.4 Implement and Manage a Firewall on Servers v8 - 4.5 Implement and Manage a Firewall on End-User Devices v7 - 9.4 Apply Host-based Firewalls or Port Filtering