A browser is only as strong as its weakest byte – Part 2

As promised, the follow up from our previous post.

Before Thanksgiving, we left off with IE9 coughing up bytes. We’ll poke it some more today and make it do a little dance for us.
Last week we managed to trick IE9 into doing an INC[ADDRESS] for us where we could specify the address. Now it is time to see how much damage we can do with just that. Since we’ll operate under the assumption that everything in the process is ASLR’d the first thing to do to is come up with a way to predict a fixed address we can safely increment. The easiest way to do that will be using an aligned heapspray. In case you’re not familiar with heapspraying, especially heap spraying in Internet Explorer, below is a quick breakdown of the basics of a heapspray. Continue reading