Faking Session/Cookies?

Question

I\'m not exactly sure how the $_SESSION work in PHP. I assume it is a cookie on the browser matched up with an unique key on the server. Is it possible to fake

Answer 1

Sessions in PHP by default store the data in a file on the server (/tmp/) and store an identifier cookie usually PHPSESSID (it will be a hexadecimal number, e.g. f00f8c6e83cf2b9fe5a30878de8c3741).

If you have someone else's identifier, then you could in theory use their session.

However, most sites check to ensure the user agent is consistent and also regenerate the session identiifer every handful of requests, to mitigate this.

As for guessing a session, it's possible, but extremely unlikely. It'd be easier to guess credit card numbers (smaller pool of characters (0-9 over 0-9a-f) and a checksum to validate it). Though of course you'd also need the expiry and security code.