Title

The RHEL 8 SSH daemon must not allow authentication using known host’s authentication. (Cat II impact)

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 Content

Verify the SSH daemon does not allow authentication using known host’s 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*ignoreuserknownhosts' IgnoreUserKnownHosts yes If the value is returned as "no", the returned line is commented out, or no output is returned, this is a finding. If conflicting results are returned, this is a finding.

Fix Text

Configure the SSH daemon to not allow authentication using known host’s authentication. Add the following line in "/etc/ssh/sshd_config", or uncomment the line and set the value to "yes": IgnoreUserKnownHosts yes 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

Additional Identifiers

Rule ID: SV-230290r1017100_rule

Vulnerability ID: V-230290

Group Title: SRG-OS-000480-GPOS-00227

Expert Comments

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