This challenge asked us to transfer $2000 to an account when all new accounts are created with only $1000.
The trick here was to spot the vulnerability. The scripts loads html from a controlled webpage with @file_get_contents(). It then parses the html for forms with regex to solves a basic math problem, with unescaped eval(). Finally the page submits a post request to the controlled webpage with file_get_contents(). With that information determined from the… Read more »