Thursday, June 18, 2009


I've just noticed that a Google search for "clusterfuzzing" (including the quotes) has no hits. Therefore, I'm reserving the term :) All I need now is a new fuzzing angle and then I've got all the makings of a great presentation!

Actually, I do have a new twist on fuzzing. All I need is the bugs. Watch this space!

Wednesday, June 10, 2009

Bonus Safari XXE (only affecting Safari 4 Beta)

Here's another XXE bug for you (resulting in file theft), just to make the point that this class of bugs is well worth watching out for in client-side applications (such as a browser :)

The good news here is that this WebKit regression was quickly fixed by Apple -- and in time for the Safari 4 final release -- so no production browser should ever have been affected. Just the Safari 4 Beta.

Full credit here to Carlos Pizano who noticed the WebKit regression due to a collision with the Chrome sandbox. I just put together the Safari test case / demo:

Tuesday, June 9, 2009

Apple's Safari 4 also fixes cross-domain XML theft

Safari 4 also fixes an interesting cross-domain XML theft. Full technical details live here:

XML theft can include highly sensitive data thanks to things like XHTML, AJAX-y RPCs using XML and authenticated RSS feeds. The example I have steals XML representing a logged-in Gmail user's inbox:

Safari 3 demo for users logged in to Gmail

I think there's a lot more room for browser-based cross-domain leaks (sometimes called UXSS or universal XSS). This is because the pace of new browser features is very high, and lots more functionality is being added that involves reference by URI. Every such addition is a possible vector for a missing or incorrect (e.g. 302 redirect tricks) cross-domain check; or even an ill-advised specification-based cross-domain leak.

This is one of the serious Safari bugs demoed but not disclosed at my PacSec and HiTB Dubai presentations. I forgot to note that my previous post on file theft was another.

Monday, June 8, 2009

Apple's Safari 4 fixes local file theft attack

Safari 4 was just released and among the various improvements is a range of security fixes. One of these fixes is for an XXE attack against the parsing of the XSL XML. Full technical details may be found here:

Or for the lazy, you can skip straight to the:

Demo for Safari 3 / MacOS
Demo for Safari 3 / Windows

I found it interesting that Safari 3 seemed robust against XXE attacks in general -- there are a lot of places that browsers find themselves parsing XML (XmlHttpRequest, prettifying XML mime type documents, SVG, E4X, etc.) However, the relatively obscure area of the XSL XML succumbed to an XXE attack.

(Note: awareness of XXE attacks remains low despite the issue being documented since at least 2002).