Dumping Lego NXT firmware off of an existing brick
20 hours ago
- #Firmware Exploitation
- #Lego NXT
- #ARM Exploit Development
- The author contributed to the Pybricks project, a MicroPython port for Lego Mindstorms hardware.
- Obtained a Lego NXT with original firmware version 1.01 from 2006 and aimed to archive it.
- Discovered arbitrary code execution as part of the firmware dumping process.
- The NXT is a simple exploitation target for ARM and embedded exploit development.
- Initial research found no archived copies of firmware version 1.01.
- Considered using the firmware updater but found it overwrites part of the firmware.
- Explored JTAG as a hardware interface but preferred a software-only solution.
- NXT programs run in a bytecode VM, restricting memory access to a fixed data segment.
- Studied the NXT firmware source code and communications protocol for vulnerabilities.
- Discovered IO-Maps, which provide access to internal module states, including a function pointer.
- Exploited the function pointer in the VM's IO-Map to achieve arbitrary code execution.
- Used Python and PyUSB to communicate with the NXT and execute custom ARM assembly code.
- Successfully dumped the firmware by reading arbitrary memory addresses.
- The exploit likely works on all NXT firmwares derived from the stock firmware.
- Potential for creating an NXT worm over Bluetooth, though discouraged for malicious use.