cis-ubuntu1804-v220-3-4-1-5

name	cis-ubuntu1804-v220-3-4-1-5
description	Ensure ufw outbound connections are configured
category	cis-networking
version	2.2.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-18.04","networking","firewall","ufw"]
cis_id	3.4.1.5
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 3.4.1.5

Description

Configure the firewall rules for new outbound connections.

Rationale

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

Impact

Changing firewall settings while connected over network can result in being locked out of the system.

Audit Procedure

Command Line

Run the following command to verify outbound connections are configured:

ufw status verbose

Verify all rules for new outbound connections match site policy.

Expected Result

Output should include rules matching site policy for outbound connections. The default outbound policy should be allow.

Remediation

Command Line

Configure ufw in accordance with site policy. The following command will allow all outbound connections:

ufw allow out on all

Default Value

ufw default outbound policy is allow.

References

1. NIST SP 800-53 Rev. 5: CA-9, 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.

4.5 Implement and Manage a Firewall on End-User Devices - Implement and manage a host-based firewall or port-filtering tool on end-user devices.

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.

Profile Applicability

• Level 1 - Server
• Level 1 - Workstation

Assessment Status

Manual