What is NexMon?

NexMon is a firmware patching framework initially built for the BCM4339 WiFi firmware of Nexus 5 smartphones. However, this repository contains firmware patches for the BCM43438 WiFi chip used in the Raspberry Pi 3. It's main intention was to enable monitor mode and frame injection, which now works quite well. Nevertheless, we have also published many example patches that allow you to dive into firmware reverse engineering and firmware patching. The ability to write firmware patches in C makes it easy to use, especially for beginners.

News

• We moved to GitHub!

WARNING

Our software may damage your hardware and may void your hardware’s warranty! You use our tools at your own risk and responsibility! If you don't like these terms, don't use nexmon!

What this Repo contains

• A bootable image (Raspbian 8) for the micro SD card (8GB) of your Raspberry Pi 3, including a patched version of airgrack-ng:
  • download
• Everything needed to build the patches by yourself

Steps needed to run the prepared SD card image on your Raspberry Pi 3

• Login as root with the password nexmon

Monitor Mode

• insmod /root/brcmfmac.ko
• thats it, try using tcpdump: tcpdump -i wlan0 -s0
• or airodump-ng: airodump-ng wlan0

Original firmware and driver

• Optional: remove the monitor mode driver rmmod brcmfmac
• cp /root/brcmfmac43430-sdio.orig.bin /lib/firmware/brcm/brcmfmac43430-sdio.bin
• use modprobe brcmfmac to load the unmodified driver and firmware

Steps to create your own firmware patches

This code is supposed to be cross-compiled on a x86 hardware. Compiling this code on the Raspberry Pi 3 itself is not supported.

• source setup_env.sh
• for the monitor mode patch: cd firmware_patching/monitor_mode/
• make
• copy the brcmfmac/brcmfmac.ko to the /root/ directory of your Raspberry Pi
• copy the brcmfmac43430-sdio.bin to /lib/firmware/brcm/ directory of your Raspberry Pi

Caveats

• Switching channels does not work it works now, but it needs a patch in the kernel, see 8f4b7501dedf72306c471e4962478b8ffe91d7a8
• Injection does not work (due to problems with the brcmfmac driver)

Read our papers

Feel free to read and reference our papers on the development of this project

• M. Schulz, D. Wegemer and M. Hollick. [NexMon: A Cookbook for Firmware Modifications on Smartphones to Enable Monitor Mode] (http://arxiv.org/abs/1601.07077), CoRR, vol. abs/1601.07077, December 2015. bibtex
• M. Schulz, D. Wegemer, M. Hollick. DEMO: Using NexMon, the C-based WiFi firmware modification framework, Proceedings of the 9th ACM Conference on Security and Privacy in Wireless and Mobile Networks, WiSec 2016, July 2016.

Contact

• Matthias Schulz [email protected]
• Daniel Wegemer [email protected]