Paul Nicholson wrote:
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Friday 25 October 2002 11:23 am, Johnson, Kirk wrote:And what should these precautions be? If a malicious user can submit his own form and you are looking for a POST variable, how can you ensure that $admin came from your form and not that user's?The problem is when a cracker uses form variables in an attempt to set the values of "flag" variables kept only in the session, for example, $isAdmin. As far as the form variables *you* put in your form, it doesn't matter whether the user submits your form or a form they made themselves. Those form variables are just data you are trying to collect. With register_globals on, PHP takes *all* variables (GET, POST, COOKIE) received from the client and assigns them to global variables. So if the user posts a value for $isAdmin, she can give herself admin privileges. The key is to retrieve *only* the form variables *you* put in the form from the the $_POST array. So don't write a loop and grab *everything* from that array. Kirk
Exactly! Not only should you retrieve *only* the vars you need from POST,
you should also filter them to make sure they contain what you're looking for.....is_alpha($_POST['name']). And no, php doesn't have an 'is_alpha' function....I created that as part of a filtering class.
- -- ~Paul Nicholson
Design Specialist @ WebPower Design
"The web....the way you want it!"
"It said uses Windows 98 or better, so I loaded Linux!"
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