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Fuzzing at Mach Speed: Uncovering IPC Vulnerabilities on MacOS

Reviews fuzzing at Mach Speed: Uncovering IPC Vulnerabilities on MacOS and evaluates key implications for security practitioners.

Summary

Speaker and audience

Mandiant/Google consultant Dylan Frankie presents year-long research on fuzzing macOS Mach IPC, aimed at offensive researchers and defensive engineers alike.

Fuzzing basics

Fuzzing sends unexpected inputs through attack vectors to trigger crashes in memory-unsafe C/C++ code, potentially exposing buffer overflows, use-after-free, and similar bugs.

Approach

He contrasts mutation-based fuzzing (mutating valid inputs) with grammar-based fuzzing, focusing on mutation for this work. The fuzzing cycle is his framework for finding and refining memory-corruption issues.

macOS IPC focus

The XNU Mach layer handles low-level IPC. Mach ports act as kernel-managed mailboxes; services register with the bootstrap server (e.g., com.apple.Troopers) so clients can allocate ports, register services, and exchange messages. He argues base Mach IPC is a high-value target because many higher-level mechanisms build on it.

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