John McDonald & Chris Valasek: Practical Windows Heap Exploitation
Augustus Ballroom 5-6
About: As we all know, the era of the straightforward 4-byte overwrite is over. Heap exploitation has steadily increased in difficulty since its genesis in Solar Designer's ground-breaking Bugtraq post in July of 2000. This trend towards increasingly complicated exploitation is primarily a result of the widespread implementation of technical heap counter-measures in modern systems software. The effort required to write reliable heap exploits has steadily increased due to other factors as well: applications have become more and more multi-threaded to take advantage of trends in hardware, and -- in certain code -- memory corruption vulnerabilities have become more nuanced and unique as a result of common, straightforward vulnerability patterns slowly but surely being audited out of existence. The end result of all these defensive machinations is that now, more than ever, you need a fluid, application-aware approach to heap exploitation. The building blocks of such an approach are an extensive working knowledge of heap internals, an understanding of the contributing factors in heap determinism, various tactics for creating predictable patterns in heap memory, and, naturally, a collection of techniques for exploiting myriad different specific types of memory corruption in heap memory.
Our talk is chiefly concerned with developing this foundational knowledge, focusing on the practical challenges of heap exploitation on Windows XP SP3 and Server 2003. While Windows Vista is gaining market share and Windows 7 is on its way, the XP code base is still the most prevalent attack surface on the Internet. XP heap exploitation may not technically qualify as "