This is a friendly and fast introduction to reverse engineering ARM microcontroller firmware, starting from a physical device and ending with firmware that can be read, understood and patched.
We’ll focus on Cortex M devices, such as the STM32 and nRF51 series. They have different architectures, registers, instruction sets, and calling conventions from x86, but they follow their own consistent rules. We’ll teach you how to rip firmware out of these devices, how to identify it and its memory map without a datasheet, and how to load it into GHIDRA or IDA Pro when no ELF headers are included.
Beginners will find a handy new type of reverse engineering, and seasoned pros will still learn some nifty tricks that they might not already know.
