DEF CON 30 - stacksmashing - The Hitchhacker’s Guide to iPhone Lightning and JTAG Hacking

stacksmashing explains the inner workings of Apple's Lightning connector and introduces the cheap, open-source Tamarin Cable for JTAG debugging.

Apple’s Lightning connector was introduced almost 10 years ago - and under the hood it can be used for much more than just charging an iPhone: Using a proprietary protocol it can also be configured to give access to a serial-console and even expose the JTAG pins of the application processor! So far these hidden debugging features have not been very accessible, and could only be accessed using expensive and difficult to acquire "Kanzi" and "Bonobo" cables. In this talk we introduce the cheap and open-source "Tamarin Cable", bringing Lightning exploration to the masses! In this talk we are diving deep into the weeds of Apple Lightning: What’s “Tristar”, “Hydra” and “HiFive”? What’s SDQ and IDBUS? And how does it all fit together? We show how you can analyze Lightning communications, what different types of cables (such as DCSD, Kanzi & co) communicate with the iPhone, and how everything works on the hardware level. We then show how we developed the “Tamarin Cable”: An open-source, super cheap (~$5 and a sacrificed cable) Lightning explorer that supports sending custom IDBUS & SDQ commands, can access the iPhone’s serial-console, and even provides a full JTAG/SWD probe able to debug iPhones. We also show how we fuzzed Lightning to uncover new commands, and reverse engineer some Lightning details hidden in iOS itself.