cis-gcp-cos-5-1-9

name	cis-gcp-cos-5.1.9
description	Ensure SSH HostbasedAuthentication is disabled
category	cis-gcp-cos
version	1.2.0
author	cyberstrike-official
tags	["cis","gcp","container-optimized-os","ssh","sshd","sshd-config","authentication"]
cis_id	5.1.9
cis_benchmark	CIS Google Container-Optimized OS Benchmark v1.2.0
tech_stack	["gcp","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

5.1.9 Ensure SSH HostbasedAuthentication is disabled (Automated)

Description

The HostbasedAuthentication parameter specifies if authentication is allowed through trusted hosts via the user of .rhosts, or /etc/hosts.equiv, along with successful public key client host authentication. This option only applies to SSH Protocol Version 2.

Rationale

Even though the .rhosts files are ineffective if support is disabled in /etc/pam.conf, disabling the ability to use .rhosts files in SSH provides an additional layer of protection.

Audit Procedure

Run the following command and verify that output matches:

# sshd -T | grep hostbasedauthentication

HostbasedAuthentication no

Expected Result

Output should show HostbasedAuthentication no.

Remediation

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

HostbasedAuthentication no

Default Value

HostbasedAuthentication no

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	6.3 Require MFA for Externally-Exposed Applications		x	x
v7	16.3 Require Multi-factor Authentication		x	x

Profile

• Level 1 - Server