How to sniff Zigbee traffic

Sniffing Zigbee traffic can be handy sometimes. E.g. when you want to analyze the commands used by a device.

Prerequisites

• Computer
  • Ubuntu machine (tested with 18.10)
  • Windows machine (tested with Windows 10)
• CC2531 stick

1. Flashing the CC2531 stick

The CC2531 needs to be flashed with a sniffer firmware. Flash the firmware using the instructions from Flashing the CC2531.

Linux

The firmware is included with PACKET-SNIFFER (not PACKET-SNIFFER-2!). Download PACKET-SNIFFER. As the sniffer firmware is only available in the windows installer we need to extact the hex file. This would require 7zip (p7zip-full or p7zip-plugins package depending on distro)

unzip swrc045z.zip -d PACKET-SNIFFER
7z e PACKET-SNIFFER/Setup_SmartRF_Packet_Sniffer_2.18.0.exe bin/general/firmware/sniffer_fw_cc2531.hex
sudo <path-to>/cc-tool -e -w <path-to>/sniffer_fw_cc2531.hex

Windows (and possibly Ubuntu)

For Windows this firmware is included with ZBOSS. Register an account and download ZBOSS Sniffer for Windows 64-bit. Included in the ZIP file is the firmware in subfolder hw\CC2531 USB dongle\zboss_sniffer.hex. Please note that ZBOSS is also available for Ubuntu.

2. Installing required tools

Ubuntu

cd /opt
sudo apt-get install -y libusb-1.0-0-dev wireshark
curl -L https://github.com/homewsn/whsniff/archive/v1.1.tar.gz | tar zx
cd whsniff-1.1
make
sudo make install

Windows

Download and install the latest version of Wireshark. ZBOSS itself is portable and won’t need to be installed.

3. Sniffing traffic

On Ubuntu start wireshark with sudo whsniff -c ZIGBEE_CHANNEL_NUMBER | wireshark -k -i -. For Windows run the ZBOSS executable in gui\zboss_sniffer.exe, enter the path to your Wireshark executable and click on the Start button.

Wireshark will start and log the Zigbee messages. As these messages are encrypted we need to add 2 encryption keys. The first one is the Trust Center link key, which is the same for (almost) every Zigbee network. The second one is the network encryption key (Transport Key).

Add the Trust Center link key by going to to Edit -> Preferences -> Protocols -> ZigBee. Set Security Level to AES-128 Encryption, 32-bit Integrity Protection and click on Edit. Click on + and add 5A:69:67:42:65:65:41:6C:6C:69:61:6E:63:65:30:39 with Byte Order Normal.

NOTE: The Hue bridge uses a different Trust Center link key

Next we need to figure out the network encryption key (Transport Key). There are two ways to do this:

1) By default, if you haven’t changed network_key in your configuration.yaml this will be 01:03:05:07:09:0B:0D:0F:00:02:04:06:08:0A:0C:0D. If you changed your network_key, then convert each number into its 2-digit hexadecimal value, and combine them all with : between. E.g. [1, 3, 5, 7, 9, 11, 13, 15, 0, 2, 4, 6, 8, 10, 12, 13] -> 01:03:05:07:09:0B:0D:0F:00:02:04:06:08:0A:0C:0D

2) If you don’t want to manually translate the numbers, the network encryption key is also exposed when a device joins the network. Pair a new device to the network (or re-pair an existing one) and grab the message where the Info is Device Announcement….. Open the message and expand ZigBee Network Layer Data -> ZigBee Security Header.

Copy the key value, as shown above and go to Edit -> Preferences -> Protocols -> ZigBee -> Edit and add the key with Byte Order Normal.

Now Wireshark is able to decrypt the messages. When e.g. turning on a light you will see a message similar to:

Troubleshooting

If you get “couldn’t run /usr/bin/dumpcap in child process: permission denied” when runnign whsniff. Check if /usr/bin/dumpcap is executable for everyone. Or chmod 755 /usr/bin/dumpcap.