Vulnerability Discussion

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

Check

Verify the SSH daemon does not allow rhosts authentication with the following command:

$ sshd -T | grep ignorerhosts

ignorerhosts yes

If the "IgnoreRhosts" keyword is set to "no", this is a finding.

Fix

Configure the SSH daemon to not allow rhosts authentication.

Add the following line to "/etc/ssh/sshd_config", or uncomment the line and set the value to "yes":

IgnoreRhosts yes

Alternatively, add the setting to an include file if the line "Include /etc/ssh/sshd_config.d/*.conf" is found at the top of the "/etc/ssh/sshd_config" file:

$ echo 'IgnoreRhosts yes' > /etc/ssh/sshd_config.d/40-rhosts.conf

Restart the SSH daemon for the settings to take effect:

$ systemctl restart sshd.service