cis-ubuntu1604-v200-5-3-19

name	cis-ubuntu1604-v200-5-3-19
description	Ensure SSH warning banner is configured
category	cis-networking
version	2.0.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-16.04","ssh","remote-access"]
cis_id	5.3.19
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 5.3.19

Description

The Banner parameter specifies a file whose contents must be sent to the remote user before authentication is permitted. By default, no banner is displayed.

Rationale

Banners are used to warn connecting users of the particular site's policy regarding connection. Presenting a warning message prior to the normal user login may assist the prosecution of trespassers on the computer system.

Audit Procedure

Command Line

Run the following command and verify that output matches:

sshd -T -C user=root -C host="$(hostname)" -C addr="$(grep $(hostname) /etc/hosts | awk '{print $1}')" | grep banner

Expected Result

banner /etc/issue.net

Remediation

Command Line

Edit the /etc/ssh/sshd_config file to set the parameter as follows:

Banner /etc/issue.net

References

1. SSHD_CONFIG(5)

CIS Controls

Version 7

5.1 Establish Secure Configurations - Maintain documented, standard security configuration standards for all authorized operating systems and software.

Profile Applicability

• Level 1 - Server
• Level 1 - Workstation

Assessment Status

Automated