Cupfighter.net

By David Lindsay & Eduardo Vela Nava

The talk is about abusing the anti-XSS filters built into IE8 to always be able to perform XSS.

Microsoft decided to implement anti-XSS measures in IE because XSS is so common. On the other hand the wanted to be careful not to break the web and to keep things performant and the solution itself had to be secure.

So how do these filters work?
•    Examine all outbound requests for XSS patterns using heuristics filters.
•    If something matches the filter a dynamic signature is generated
•    If the signature matches then the response is neutered.
Read more…

In this post from 19-6 Mozilla make a clear case for supporting content security policies.

A content security policy, which is specified here, can impose common sense security restrictions on the (active) content of site.

A content security policy can completely kill Cross Site Scripting if it is set to:

1. Require that all javascript is loaded from an external file
2. This file resides at a specified location