Obtaining Keys in Zigbee Standard Security Network

[David_Purser]

Issue

Capturing packets from Zigbee Standard Security Network shows packets marked Bad FCS or Encrypted Payload

Product Line

EcoStruxure Building Operation

Environment

• Building Operation Automation Server
• Building Operation Room Controller

Cause

Zigbee Standard Security Networks implement multiple keys to encrypt data for the Zigbee Network and each device

Resolution

This resolution assumes you have a Zigbee adapter that can capture packets in Wireshark.

Ensure zigbee_pc_keys are available in each profile you are going to use to analyze the Zigbee packets. The file location is generally: %AppData%\Roaming\Wireshark\profiles\<Profile Name>\zigbee_pc_keys

1. Open Wireshark and configure the Zigbee adapter
   1. NOTE: Please substitute your adapter name if not using the TI CC2531 adapter.
   2. Open Wireshark
   3. Click the gear next to the 'TI CC2531 802.15.4 packet sniffer'
   4. Select the known channel (11-26) and click Save
   5. Click on 'TI CC2531 802.15.4 packet sniffer' to start capturing
2. Update formatting to resolve Bad FCS packets
   1. Go to Edit -> Preferences -> Protocols
   2. Select IEEE 802.15.4
      1. Depending on your Wireshark version,
      2. check or "TI CC24XX FCS Format"
      3. or set FCS format = "TI CC24xx metadata"
3. Add default link key for Zigbee Alliance
   1. Go to Edit -> Preferences -> Protocols
   2. Select ZigBee
      1. Set Security Level = AES-128 Encryption, 32-bit Integrity Protection
      2. Click Edit next to Pre-configured Keys
         1. Click + and Enter Wireshark Key from below, Byte Order = Normal, and Label
   3. Enter the Zigbee Alliance Default Link Key
      1. Key = 5A:69:67:42:65:65:41:6C:6C:69:61:6E:63:65:30:39
      2. Key Value = 5A6967426565416C6C69616E63653039
         1. Remove colons (:) for entry into Wireshark
      3. ByteOrder = Normal
      4. Label = ZigbeeAlliance09
4. Find and add Standard Network Key
   1. Ensure you have configured the default transport key (above).
   2. Use this display filter to find the request Key exchange: zbee.sec.decryption_key
   3. Find Standard Network Key
      1. Look in the Info column for the Transport Key and select it
      2. Expand Zigbee Application Support Layer Command
      3. Expand Command Frame: Transport Key to see Key Type: Standard Network Key and Key: shows the value
      4. Right-click on the key -> Copy -> Value
      5. Right-click on the Zigbee Network Layer Data -> Protocol Preferences -> Open Zigbee Network Layer Preferences
      6. Click Edit next to Pre-configured Keys
      7. Click + and paste under Key, leave Byte Order = Normal, and add Label.
         1. RECOMMENDED: Use Descriptive label because you will have Network Key per Zigbee Network, so includes Device, PAN ID, and NetworkKey, ie ASP087_12345_NetworkKey
5. Find and add Trust Center Link Key PER device
   1. Ensure the following are configured: formatting, transport key, and Standard Network Key (above).
   2. Use this display filter to find the request Key exchange: zbee.sec.decryption_key
   3. Since this is per device, one can include the Network Address for the device. Example: If the network address of the device is 0x2074, the display filter would be: zbee.sec.decryption_key and zbee_nwk.addr == 0x2074
   4. Find Trust Center Link Key per device
      
      1. Using the Info field, find the pair of Request Key and Transport Key. The Request Key will have Source = Device Network Address, and the Transport Key will have the Destination = Device Network Address.
      2. Click on the Transport Key packet
      3. Expand Zigbee Application Support Layer Command
      4. Expand Command Frame: Transport Key to see Key Type: Trust Center Link Key and Key: shows the value
      5. Right-click on the key -> Copy -> Value
      6. Right-click on the Zigbee Network Layer Data -> Protocol Preferences -> Open Zigbee Network Layer Preferences
      7. Click Edit next to Pre-configured Keys
      8. Click + and paste under Key, leave Byte Order = Normal, and add Label.
         1. RECOMMENDED: Use a Descriptive label because you will have a Key per device, so includes Device, Network Address, and Trust Center Link Key, ie TH907-01_0x2074_TCLK