The OL 8 SSH daemon must not allow Kerberos authentication, except to fulfill documented and validated mission requirements.

STIG ID: OL08-00-010521  |  SRG: SRG-OS-000480-GPOS-00227 | Severity: medium |  CCI: CCI-000366

Vulnerability Discussion

Configuring this setting for the SSH daemon provides additional assurance that remote logon via SSH will require a password, even in the event of misconfiguration elsewhere.

Check

Verify the SSH daemon does not allow Kerberos authentication with the following command:

$ sudo grep -ir "KerberosAuthentication" /etc/ssh/sshd_config*

KerberosAuthentication no

If the value is returned as "yes", the returned line is commented out, or no output is returned, or has not been documented with the ISSO, this is a finding.
If conflicting results are returned, this is a finding.

Fix

Configure the SSH daemon to not allow Kerberos authentication.

Add the following line in "/etc/ssh/sshd_config", or uncomment the line and set the value to "no":

KerberosAuthentication no

The SSH daemon must be restarted for the changes to take effect. To restart the SSH daemon, run the following command:

$ sudo systemctl restart sshd.service