Breaking the Sound Barrier Part I: Fuzzing CoreAudio with Mach Messages
Guest post by Dillon Franke, Senior Security Engineer, 20% time on Project Zero Every second, highly-privileged MacOS system daemons accept and process hundreds of IPC messages. In some cases, these message handlers accept data from sandboxed or unprivileged processes. In this blog post, I’ll explore using Mach IPC messages as an attack vector to find and exploit sandbox escapes. I’ll detail how I used a custom fuzzing harness, dynamic instrumentation, and plenty of debugging/static analysis to identify a high-risk type confusion vulnerability in the coreaudiod system daemon. Along the way, I’ll discuss some of the difficulties and tradeoffs I encountered. [...]