The Photon operating system must configure sshd to ignore user-specific "known_host" files.

Secure Shell (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 that must also be ignored while disabling host-based authentication generally.

At the command line, run the following command:

# sshd -T|&grep -i IgnoreUserKnownHosts

Expected result:

IgnoreUserKnownHosts yes

If the output does not match the expected result, 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