Vulnerability Discussion

If an account has an empty password, anyone could log on and run commands with the privileges of that account. Accounts with empty passwords must never be used in operational environments.

Satisfies: SRG-OS-000106-GPOS-00053, SRG-OS-000480-GPOS-00229

Check

Verify Amazon Linux 2023 remote access using SSH prevents logging on with a blank password with the following command:

$ sudo grep -ir PermitEmptyPasswords /etc/ssh/sshd_config /etc/ssh/sshd_config.d/
/etc/ssh/sshd_config:PermitEmptyPasswords no

If the "PermitEmptyPassword" keyword is set to "yes", is missing, or is commented out, this is a finding.

Fix

Configure Amazon Linux 2023 to prevent SSH users from logging on with blank passwords.

Edit the following line in "etc/ssh/sshd_config" or in a file in "/etc/ssh/sshd_config.d":

PermitEmptyPasswords no

Restart the SSH daemon for the settings to take effect:

$ sudo systemctl restart sshd.service