The SSH daemon must not permit Kerberos authentication unless needed.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
GEN005526-ESXI5-000105	GEN005526-ESXI5-000105	GEN005526-ESXI5-000105_rule		Low

Description
Kerberos authentication for SSH is often implemented using GSSAPI. If Kerberos is enabled through SSH, the SSH daemon 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 daemon 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
VMware ESXi v5 Security Technical Implementation Guide	2013-01-15

Details

Check Text ( C-GEN005526-ESXI5-000105_chk )
Disable lock down mode. Enable the ESXi Shell. Login as root and execute the following command(s): # grep KerberosAuthentication /etc/ssh/sshd_config If "KerberosAuthentication" is set to "yes" or the keyword/line is missing, this is a finding. Re-enable lock down mode.

Fix Text (F-GEN005526-ESXI5-000105_fix)
Disable lock down mode. Enable the ESXi Shell. Login as root and execute the following command(s): # vi /etc/ssh/sshd_config Add/modify the "KerberosAuthentication" keyword to "no", i.e.; KerberosAuthentication = no Re-enable lock down mode.