Previous work on kernel heap exploitation for iOS or Mac OS X has only covered attacking the freelist of the kernel heap zone allocator. It was however never discussed before what other kernel heap memory allocators exist or what kernel heap allocation functions wrap these allocators. Attacks against further heap meta data or attacking kernel application data has not been discussed before.
This talk will introduce the audience to the big picture of memory allocators in the iOS kernel heap. It will be shown how attacks can be carried out against other meta data stored by other allocators or wrappers. It will be shown how memory allocated into different zones or allocated by different allocators is positioned to each other and if cross attacks are possible. It will be shown how overwriting C++ objects inside the kernel can result in arbitrary code execution. Finally this talk will leverage this to present a generic technique that allows to control the iOS kernel heap in a similar fashion as JavaScript is used in today's browser exploits to control the user space heap.
Stefan Esser is best known in the security community as the PHP security guy. Since he became a PHP core developer in 2002 he devoted a lot of time to PHP and PHP application vulnerability research. However in his early days he released lots of advisories about vulnerabilities in software like CVS, Samba, OpenBSD or Internet Explorer. In 2003 he was the first to boot Linux directly from the hard disk of an unmodified XBOX through a buffer overflow in the XBOX font loader. In 2004 he founded the Hardened-PHP Project to develop a more secure version of PHP, known as Hardened-PHP, which evolved into the Suhosin PHP Security System in 2006. Since 2007 he works as head of research and development for the German web application company SektionEins GmbH that he cofounded.