Warning: This post contains a solution!
Only continue if:
1.) you want to see a possible alternative solution or
2.) you are stuck and need a hint!
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The message on the page is:
There is nothing on this page
A look into the source code of the page shows a comment.
<div id="content"> There is nothing on this page <!-- No more information leaks!! Not even Google will find it this time... --> </div>
Not even Google will find it this time... is a hint for the file
robots.txt, which can tell search engines or crawlers what behavior the page owner wants on his homepage.
The content of this file is:
User-agent: * Disallow: /s3cr3t/
This means, that every User-agent is disallowed to crawl/list the folder
s3cr3t. This directory contains the file
users.txt with the password for the next level.