The fact that $_REQUEST was used is a huge red flag as well.
edit: I should expand a bit: $_REQUEST is a nono, it should be $_GET or $_POST depending on the request. The actual badness of request is that it also contains everything in $_COOKIE as well.
edit: I should expand a bit: $_REQUEST is a nono, it should be $_GET or $_POST depending on the request. The actual badness of request is that it also contains everything in $_COOKIE as well.