Title

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

Discussion

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.

Check Content

Check the SSH daemon configuration. Note that keywords are case-insensitive and arguments (args) are case-sensitive. keyword=GSSAPIAuthentication arg(s)=no Default values include: "no" Note: When the default "arg" value exactly matches the required "arg" value (see above), the <keyword=arg> entry is not required to exist (commented or uncommented) in the ssh (client) or sshd (server) configuration file. While not required, it is recommended that the configuration file(s) be populated with all keywords and assigned arg values as a means to explicitly document the ssh(d) binary's expected behavior. Examine the file. # cat /opt/ssh/etc/sshd_config | tr '\011' ' ' | tr -s ' ' | sed -e 's/^[ \t]*//' | grep -v '^#' | grep -i "GSSAPIAuthentication" If the return value is yes, this is a finding.

Fix Text

Edit the SSH daemon configuration and delete the keyword entry or modify the entry as follows: GSSAPIAuthentication no

Additional Identifiers

Rule ID: SV-35066r1_rule

Vulnerability ID: V-22473

Group Title: GEN005524

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