Black Hat Briefings, Usa 2007 [audio] Presentations From The Security Conference.

Traditional exploitation techniques of overwriting heap metadata has been discussed ad-nauseum, however due to this common perspective the flexibility in abuse of the heap is commonly overlooked. This presentation examines a flaw that was found in several popular open-source applications including mod_auth_kerb (Apache Kerberos Authentication), Samba, Heimdal, OpenBSDs kerberos implementation (not exploitable), and so on, as a method for exploring heap structure exploitation and hopefully providing a gateway to understanding the true beauty of data structure exploitation. This focuses on the dynamic memory management implementation provided by the GNU C library, particularly ptmalloc2 and presents methods for evading certain sanity checks in the library along with previously unpublished methods for obtaining control.