Introduced with the iPhone 5 nearly two and a half years ago, Apple’s Lightning connector has stymied the incredible homebrew electronics scene that was previously accustomed to the larger, older, better documented, and more open 30-pin connector. Now, finally, the protocols inside the Apple Lightning connector have been broken. We’re still a ways off from a Lightning breakout board, but this is the first proof that a serial console can be obtained through a Lightning connector. That’s the first step to totally owning an iDevice, and this is how all those exploits will start.
[Ramtin Amin] began the teardown of the Lightning connector began as most reverse engineering tasks should – looking at the patents, finding a source for the connectors, and any other products that use similar hardware. [Ramtin] found a Lightning to Serial converter powered by an STM32 microcontroller. Disassembling the firmware and looking at the output on a logic analyzer, [Ramtin] figured out part of the protocol, most of the wiring, and after some research, schematics for how an until-now unidentified chip in Lightning-enabled iProducts was wired.
The chip in question is colloquially known as the Tristar, and more accurately as a CBTL1608A1. During the teardown craze of the iPhone 5 launch, this chip was frequently identified as a DisplayPort Multiplexer. It is a mux, but not for DisplayPort – it’s only to connect the accessory (Lightning) UART, debug UART, baseband, SoC, and JTAG. This is the key to the castle, and being able to get through this chip means we can now own our iDevices.
The chip is an incredibly small BGA affair that [Ramtin] desoldered, reflowed onto a breakout board, and connected to an STM32 Discovery board. Using the techniques he used with other Lightning-enabled hardware, [Ramtin] was able to connect his iPhone and ever so slightly peek his head into the inner workings of his device.
It’s not complete control of an iDevice yet, but this is how all those future exploits will start. [Ramtin] uploaded a short video as a proof of concept, you can check that out below.