Level 5 - Level 6

Username: natas6
Password: fOIvE0MDtPTgRhqmmvvAOt2EfXR6uQgR
URL:      http://natas6.natas.labs.overthewire.org

This time the page welcomed me with an input box requesting for a secret. Also there was a link "View sourcecode".

The link lead to index-source.html page, which had the logic that is behind the verification of the secret key that we enter as input. The variable $secret, which is used in the code is imported from the file/path includes/secret.inc.

The path includes/secret.inc [ http://natas6.natas.labs.overthewire.org/includes/secret.inc ] had the value for the variable $secret.

On entering the found secret value in the input, got the password for the next level.