This is a quick and easy method for receiving the backend IP (1) of a server who is hidden behind a proxy (2) or a firewall (3).
Requiring the following:
- Attacker can use a browser
- Or Attacker have a basic knowledge of PHP (4)
- A page who provides the "Upload through URL" option
In this case the attacker only need a working browser and have to visit the following page:
Then press in the window "Invisible logger" the button "Generate logger"
Now we will be redirected to a new page. URL would be for example:
all we need is copying the "No BB Code" link out of it
and paste it into the "Upload via URL" form
After our upload finished, we can visit our generated link again and voila backend IP dropped:
After a quick check:
- Original IP: 18.104.22.168| USA | Lightcrest LLC
- Backend IP: 22.214.171.124 | USA | Lightcrest LLC
we are finished!
Of course in this case we dont know if its the true backend IP of wonderhowto it was just an example.
Many skidforums blacklistening the domain of the script shown above. But with basic skills of PHP and simple knowledge of rewrite rules we can build and spoof our own IP logger. for example:
RewriteRule ^image.png$ iplogger.php
The server is fetching our "image" from the URL we provided and saving it to a temporary cache. Thats how we reiving the true IP address of the server who is working with the image.