Vulnerability 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

To determine how the SSH daemon's "PermitEmptyPasswords" option is set, run the following command:

# grep -i PermitEmptyPasswords /etc/ssh/sshd_config
PermitEmptyPasswords no

If no line, a commented line, or a line indicating the value "no" is returned, the required value is set.

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

Fix

To explicitly disallow remote logon from accounts with empty passwords, add or correct the following line in "/etc/ssh/sshd_config":

PermitEmptyPasswords no

The SSH service must be restarted for changes to take effect. Any accounts with empty passwords should be disabled immediately, and PAM configuration should prevent users from being able to assign themselves empty passwords.