Information
The operating system must be configured so that the SSH daemon does not permit Generic Security Service Application Program Interface (GSSAPI) authentication unless needed.
Rationale:
GSSAPI authentication is used to provide additional authentication mechanisms to applications. Allowing GSSAPI authentication through SSH exposes the system's GSSAPI to remote hosts, increasing the attack surface of the system. GSSAPI authentication must be disabled unless needed.
Solution
Uncomment the GSSAPIAuthentication keyword in /etc/ssh/sshd_config (this file may be named differently or be in a different location if using a version of SSH that is provided by a third-party vendor) and set the value to no:
Example: vim /etc/ssh/sshd_config
Add, uncomment or update the following line:
GSSAPIAuthentication no
The SSH service must be restarted for changes to take effect.
# systemctl restart sshd.service
If GSSAPI authentication is required, it must be documented, to include the location of the configuration file.
Notes:
This Benchmark recommendation maps to:
Red Hat Enterprise Linux 7 Security Technical Implementation Guide:
Version 2, Release: 3 Benchmark Date: 26 Apr 2019
Vul ID: V-72259
Rule ID: SV-86883r3_rule
STIG ID: RHEL-07-040430
Severity: CAT II