5.2.27 Ensure SSH does not permit GSSAPI

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

See Also

https://workbench.cisecurity.org/files/2688

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6b.

Plugin: Unix

Control ID: 7116074798ffa3d0ea39ca93aa0dc9fac36e1f3e5c0e9231a8b74fabdc10931b