Every web developer knows how to make a GET redirect, in fact they've probably done it numerous times. However very few people know the same can be done for POST requests, in some instances completely transparently to the user. This by itself make not seem like an issue, but when you combine it with XSS it can be a very powerful to used to scam users. Consider the following scenario. A user goes to a trusted site where XSS had modified the action field of the login POST form, pointing it to http://p0wn3d.com/post.php. When user submits a request it goes to a 3rd party site, which captures the login credentials and then redirects the POST data to the original site. In the end to the user has no clue something sinister had happened because they never see p0wn3d.com. In fact the everything appears to have worked as intended. So how does this work. Ability to redirect POST comes as a courtesy of the little known 307 redirect code. Which in PHP can be forced in the following manner: [php] header("Location:...