During the presentation "iOS Kernel Exploitation" at Blackhat/Syscan 2011, Stefan Esser provided some details about how to build an iDevice (iPad/iPod/iPhone) cable that could be used to enable serial console functionality and kernel debugging capabilities within an iOS device. The following instructions will show the complete steps needed to build this cable as some of the information within the publicly available slides was found to be incomplete. You will need the following materials to build this cable:
* Soldering Iron, Solder, Wire, Wire Cutters & Wire Strippers.
* 2x mini-USB-B to USB-A cables
* FT232RL USB to Serial break-out board
* PodGizmo PodBreakout (v1.5 used here)
* 470k (or near enough to 500k) resistor
* An old iPhone or similar for testing purposes.
Please be aware that this is not an Apple approved accessory and connecting it to your IDevice is unsupported and you may damage the iDevice. I cannot be held responsible for anything you choose to do with your equipment or indeed this cable!
Step 1: Apple iOS Serial/USB Cable for Kernel Debugging
Solder pieces of wire to pin 12, pin 13 and pin 18 of the PodBreakout v1.5 board. You may wish to construct the PodBreakout plastic housing AFTER construction (despite what is shown here) to ease soldering to the PCB. With the three short pieces of wire attach (3cm or so) solder the 470k resistor to pin 21. You will also need to solder a piece of wire of similar length to pin 1 and the last leg of the resistor to the same location.
Step 2: Apple iOS Serial/USB Cable for Kernel Debugging
You should now have four pieces of wire and a resistor soldered to the PodBreakout PCB. You will now solder these four pieces of wire to the FT232RL break-out board which will be used to provide serial capabilities to the UART. The resistor between pin 1 and pin 21 of the PodBreakout is an "accessory" indicator, this indicates to the connected iPhone/iPad that serial connectivity is to be enabled by placing resistance between the two pins.