RHEL 9 /etc/shadow- file must have mode 0000 or less permissive to prevent unauthorized access.

The "/etc/shadow-" file is a backup file of "/etc/shadow", and as such, contains the list of local system accounts and password hashes. Protection of this file is critical for system security.

Verify that the "/etc/shadow-" file has mode "0000" with the following command:

$ sudo stat -c "%a %n" /etc/shadow-

0 /etc/shadow-

If a value of "0" is not returned, this is a finding.

Change the mode of the file "/etc/shadow-" to "0000" by running the following command:

$ sudo chmod 0000 /etc/shadow-