cis-ubuntu1804-v220-3-4-3-1-3

name	cis-ubuntu1804-v220-3-4-3-1-3
description	Ensure ufw is uninstalled or disabled with iptables
category	cis-networking
version	2.2.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-18.04","networking","firewall","iptables"]
cis_id	3.4.3.1.3
cis_benchmark	CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0 - Control 3.4.3.1.3

Description

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

• Uses a command-line interface consisting of a small number of simple commands
• Uses iptables for configuration

Rationale

Running iptables.persistent with ufw enabled may lead to conflict and unexpected results.

Impact

None.

Audit Procedure

Command Line

Run the following commands to verify that ufw is either not installed or disabled. 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.

Run the following command to verify ufw is disabled:

ufw status

Expected output: Status: inactive

Run the following commands to verify that the ufw service is masked:

systemctl is-enabled ufw

Expected output: masked

Expected Result

ufw is not installed, or Status: inactive and masked.

Remediation

Command Line

Run one of the following commands to either remove ufw or stop and mask ufw:

Run the following command to remove ufw:

apt purge ufw

-OR-

Run the following commands to disable ufw:

ufw disable
systemctl stop ufw
systemctl mask ufw

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

Default Value

ufw is installed and enabled by default.

References

1. NIST SP 800-53 Rev. 5: SC-7
2. CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0

CIS Controls

Version 8

4.4 Implement and Manage a Firewall on Servers - Implement and manage a firewall on servers, where supported.