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RHEL-09-255140 RHEL 9 SSH daemon must not allow Kerberos authentication.

DISA STIG library V2R10
All changes in this version
first version loaded CAT II

Maps to CM-5(1) via CCI-001813

Title

RHEL 9 SSH daemon must not allow Kerberos authentication.

Control

Verify the SSH daemon does not allow Kerberos authentication with the following command: $ sudo /usr/sbin/sshd -dd 2>&1 | awk '/filename/ {print $4}' | tr -d '\r' | tr '\n' ' ' | xargs sudo grep -iH '^\s*kerberosauthentication' KerberosAuthentication no If the value is returned as "yes", the returned line is commented out, no output is returned, and the use of Kerberos authentication has not been documented with the information system security officer (ISSO), this is a finding.

Discussion

Kerberos authentication for SSH is often implemented using Generic Security Service Application Program Interface (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 implementations may be subject to exploitation. Satisfies: SRG-OS-000364-GPOS-00151, SRG-OS-000480-GPOS-00227

Related controls

CCI-001813

Fix

Configure the SSH daemon to not allow Kerberos authentication. Add the following line in "/etc/ssh/sshd_config" or to a file in "/etc/ssh/sshd_config.d", or uncomment the line and set the value to "no": KerberosAuthentication no The SSH service must be restarted for changes to take effect: $ sudo systemctl restart sshd.service