Advanced Cycript and Substrate

This report is a technical guide demonstrating advanced use of cycript and Cydia Substrate to dynamically hook Objective‑C methods in iOS applications, enabling analysts to observe and modify data flows in custom, encrypted protocols that evade standard interception tools. It explains how to attach to processes, log via syslog, differentiate and hook class vs. instance methods, extract function pointers and signatures, and includes a case study hooking a sendJson method to capture and alter JSON payloads, illustrating practical techniques for testing protocol security without decrypting traffic on the wire.