The Photon operating system must configure Secure Shell (SSH) to ignore user-specific known_host files.

SSH trust relationships enable trivial lateral spread after a host compromise and therefore must be explicitly disabled. Individual users can have a local list of trusted remote machines, which must also be ignored while disabling host-based authentication generally.

At the command line, run the following command to verify the running configuration of sshd:

# sshd -T|&grep -i IgnoreUserKnownHosts

Expected result:

ignoreuserknownhosts yes

If "IgnoreUserKnownHosts" is not set to "yes", this is a finding.

Navigate to and open:

/etc/ssh/sshd_config

Ensure the "IgnoreUserKnownHosts" line is uncommented and set to the following:

IgnoreUserKnownHosts yes

At the command line, run the following command:

# systemctl restart sshd.service