Vulnerability Discussion

SSH trust relationships mean a compromise on one host can allow an attacker to move trivially to other hosts.

Check

Verify the operating system does not allow a noncertificate trusted host SSH logon to the system with the following command:

$ sudo grep -ir hostbasedauthentication /etc/ssh/sshd_config /etc/ssh/sshd_config.d/*

HostbasedAuthentication no

If the "HostbasedAuthentication" keyword is not set to "no", is missing, or is commented out, this is a finding.

If the required value is not set, this is a finding.

Fix

To configure RHEL 9 to not allow a noncertificate trusted host SSH logon to the system add or modify the following line in "/etc/ssh/sshd_config".

HostbasedAuthentication no

Restart the SSH daemon for the settings to take effect:

$ sudo systemctl restart sshd.service