Title

The SSH daemon must not permit Kerberos authentication unless needed. (Cat III impact)

Discussion

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.

Check Content

Ask the SA if Kerberos authentication is used by the system. If it is, this is not applicable. Check the SSH daemon configuration for the KerberosAuthentication setting. # grep -i KerberosAuthentication /etc/ssh/sshd_config | grep -v '^#' If no lines are returned, or the setting is set to "yes", this is a finding.

Fix Text

Edit the SSH daemon configuration and set (add if necessary) the "KerberosAuthentication" directive set to "no". Restart the SSH daemon. # /sbin/service sshd restart

Additional Identifiers

Rule ID: SV-46087r2_rule

Vulnerability ID: V-22475

Group Title: GEN005526

Expert Comments

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