cis-ubuntu1604-v200-3-5-1-5

name	cis-ubuntu1604-v200-3-5-1-5
description	Ensure ufw outbound connections are configured
category	cis-networking
version	2.0.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-16.04","firewall"]
cis_id	3.5.1.5
cis_benchmark	CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0 - Control 3.5.1.5

Profile

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

Description

Configure the firewall rules for new outbound connections.

Notes:

• Changing firewall settings while connected over network can result in being locked out of the system.
• Unlike iptables, when a new outbound rule is added, ufw automatically takes care of associated established connections, so no rules for the latter kind are required.

Rationale

If rules are not in place for new outbound connections all packets will be dropped by the default policy preventing network usage.

Audit Procedure

Command Line

Run the following command and verify all rules for new outbound connections match site policy:

ufw status numbered

Remediation

Command Line

Configure ufw in accordance with site policy. The following commands will implement a policy to allow all outbound connections on all interfaces:

ufw allow out on all

References

None

CIS Controls

Version 7

9.4 Apply Host-based Firewalls or Port Filtering - Apply host-based firewalls or port filtering tools on end systems, with a default-deny rule that drops all traffic except those services and ports that are explicitly allowed.