The SSH client must not permit Kerberos authentication unless needed.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-22476	GEN005527	SV-26770r1_rule	ECSC-1	Low

Description
Kerberos authentication for SSH is often implemented using GSSAPI. If Kerberos is enabled through SSH, the SSH client provides a means of access to the system's Kerberos implementation. Vulnerabilities in the system's Kerberos implementation may then be subject to exploitation. To reduce the attack surface of the system, the Kerberos authentication mechanism within SSH must be disabled for systems not using this capability.

Description

Kerberos authentication for SSH is often implemented using GSSAPI. If Kerberos is enabled through SSH, the SSH client provides a means of access to the system's Kerberos implementation. Vulnerabilities in the system's Kerberos implementation may then be subject to exploitation. To reduce the attack surface of the system, the Kerberos authentication mechanism within SSH must be disabled for systems not using this capability.

STIG	Date
Draft AIX Security Technical Implementation Guide	2011-08-17

Details

Check Text ( C-27779r1_chk )
Ask the SA if the system uses Kerberos authentication. If it does, this is not applicable. Check the SSH clients configuration for the Kerberos authentication setting. # grep -i KerberosAuthentication /etc/ssh/ssh_config \| grep -v '^#' If no lines are returned, or the setting is set to yes, this is a finding.

Fix Text (F-24021r1_fix)
Edit the SSH client configuration and set (add if necessary) a KerberosAuthentication directive set to no.