BrakTooth Proof of Concept

1) Requirements

BrakTooth requires a specific BT hardware development kit (ESP-WROVER-KIT) to be able to launch the attack since LMP packets cannot be sent from the host in normal Bluetooth Hardware.

• Ubuntu 18.04

  You can use a virtual machine with VMWare and USB 3.0 or more enabled. This is important to reduce USB latency! We recommend that a machine with native Ubuntu 18.04 is used since we rely in USB low-latency for correct Baseband interception with ESP32 proprietary LMP stack. However, most exploits will work fine if using VMWare with USB 3.0 or more enabled.

• Hardware Board: ESP-WROVER-KIT

2) Installation Instructions

A) Install (flash) PoC firmware on ESP-WROVER-KIT

First, connect ESP32-WROVER-KIT to your PC. You can check if two serial ports were added by running ls /dev/ttyUSB*. Normally, ESP32-WROVER-KIT adds two serial ports such as /dev/ttyUSB0 and /dev/ttyUSB1. We want the second serial port, which is used for serial communication with ESP32.

sudo apt install unzip python3-dev
unzip esp32driver.zip # Extract esp32driver.zip (firmware package)
cd release
python3 firmware.py flash /dev/ttyUSB1 # Please change your serial port to match your ESP32 device.
# You may need to press and hold the "Boot" button during the flashing process.
cd ../

B) Extract wdissector package and install system requirements

# Install zstandard
sudo apt install zstd
# Extract the wdissector compressed file
tar -I zstd -xf wdissector.tar.zst
cd wdissector
# Install package requirements for Ubuntu 18.04
# It installs python3, nodejs, and system packages using apt-get
./requirements.sh

3) Running BT fuzzer

You can start the fuzzer as follows:

sudo bin/bt_fuzzer --scan # Scan for targets (BDAddress) for 15 seconds
sudo bin/bt_fuzzer # Start fuzzer with graphical user interface (GUI)
sudo bin/bt_fuzzer --no-gui --autostart --target=E8:D0:3C:94:2C:66  # Start fuzzer without GUI  

BT Command line options

sudo bin/bt_fuzzer --help
Bluetooth Classic Fuzzer (Baseband, LMP, L2CAP, etc)
Usage:
  BT Fuzzer [OPTION...]

      --help               Print help
      --default-config     Start with default config
      --autostart          Automatically start (default: true)
      --no-gui             Start without GUI
      --test-webview       Test GUI webview performance (requires internet)
      --live-capture       Open wireshark in live capture mode
      --exploit [=arg(=)]  Exploit Name
      --list-exploits      List all exploits
      --host arg           Host BDAddress
      --host-port arg      Host serial port name of BT Interface 
                           (ESP-WROVER-KIT)
      --random_bdaddress   Enable/Disable host BDAddress randomization
      --target arg         Target BDAddress (default: /dev/ttyUSB1)
      --target-port arg    Target serial port name to detect crashes 
                           (default: /dev/ttyUSB2)
      --target-baud arg    Target baud rate (default: 115200)
      --bounding           Enable/Disable Bounding (default: true)
      --iocap arg          IO Capabilities (default: 3)
      --authreq arg        Authentication Request flag (default: 3)
      --scan               Scan BT Targets

3.1) Running Experimental Fuzzers:

Wi-Fi AP Fuzzer (WIP)

Wi-Fi AP Fuzzer requires use of Alpha AWUS036AC Wi-Fi Dongle and installation of our custom driver for it: cd src/drivers/wifi/rtl8812au && make -j4. Then, the Wi-FI AP fuzzer will load the custom driver on program startup:

sudo bin/wifi_ap_fuzzer # Start fuzzer without graphical interface

• Wi-Fi options such as SSID, password, authentication and channel can be changed on configs/wifi_ap_config.json.
• Note that the parameter WifiInterface must match your dongle interface name, which is usually wlan1.
• By default, the fuzzer run its main thread on the core defined by the parameter MainThreadCore=2. Make sure to change this parameter value if you prefer to run the fuzzer in a different core.
• Logs are saved on folder logs/wifi_ap

Wi-Fi AP Command line options

Wi-Fi AP 802.11 Fuzzer (MAC, LLC, SNAP, EAPoL, etc)
Usage:
  Wi-Fi AP Fuzzer [OPTION...]

      --help               Print help
      --default-config     Start with default config
      --autostart          Automatically start (default: true)
      --exploit [=arg(=)]  Exploit Name
      --fuzz               Enable/Disable fuzzing (default: true)

BLE Host Fuzzer (WIP)

BLE Host fuzzer uses the same ESP32 development kit and can be run via the command

sudo bin/bthost_fuzzer # Start fuzzer without graphical interface

• Logs are saved on folder logs/BTHost

4) BT Exploits Usage Instructions

Note: For now, Non-compliance tests may not work for any BT device. We will improve the non-compliance scripts to validate generic BT devices as well as include more details on such tests during the upcoming weeks.

List Exploits

BT Exploiter has several exploits which can be listed by running the following command:

sudo bin/bt_exploiter --list-exploits # Run as root

Available Exploits:
--> 'invalid_timing_accuracy'
--> 'repeated_host_connection'
--> 'sdp_unkown_element_type'
--> 'knob'
--> 'au_rand_flooding'
--> 'lmp_max_slot_overflow'
--> 'duplicated_encapsulated_payload'
--> 'feature_response_flooding'
--> 'lmp_overflow_dm1'
--> 'invalid_feature_page_execution'
--> 'feature_req_ping_pong'
--> 'truncated_sco_link_request'
--> 'paging_scan_disable'
--> 'invalid_max_slot'
--> 'truncated_lmp_accepted'
--> 'invalid_setup_complete'
--> 'duplicated_iocap'
--> 'lmp_auto_rate_overflow'
--> 'lmp_overflow_2dh1'
--> 'noncompliance_invalid_stop_encryption'
--> 'wrong_encapsulated_payload'
--> 'noncomplicance_duplicated_encryption_request'
--> 'sdp_oversized_element_size'

Scan target

Before launching the attack, you need to know the BDAddress of the target BT device. To facilitate this, BT Exploiter can scan the BDAddress of targets nearby by running the following command:

sudo bin/bt_exploiter --scan

If ESP32 is detected by bt_exploiter and scanning works, then you should get a similar output to the Figure below.

Launch the Attack!

Now it is your turn! Choose an exploit by its name and remember the target BDAddress where the exploit needs to be launched. You need to specify both the name of the exploit and the target BDAddress as follows to launch the respective attack:

sudo bin/bt_exploiter --host-port=/dev/ttyUSB1 --target=<target bdaddress> --exploit=<exploit name>

The argument --target is your target BDAddress and --host-port must match with the correct ESP32-WROVER-KIT serial port.

For example, launching the exploit for LMP AU Rand Flooding (au_rand_flooding) can be accomplished as follows:

sudo bin/bt_exploiter --host-port=/dev/ttyUSB1 --target=a4:50:46:59:0c:90 --exploit=au_rand_flooding

If the target is vulnerable, then you should get some anomalous behavior from the target (shutdown, reboot, etc) or simply not be able to discover it anymore when scanning for BT targets again.

An example of a successful attack output for a vulnerable target that shuts down after the attack is presented below.

Modify Exploits (Tutorial)

The source code of all exploits (C/C++) is included in folder modules/exploits. Any change to an existing exploit or new file that you add in this folder will be automatically identified and compiled the next time you run bt_fuzzer or bt_exploiter.

For more details on how to create BT exploits, please read exploit_modules_tutorial.pdf included in this repository.

Opening the capture files in Wireshark

The exploit tool includes a standalone version of Wireshark which already includes a plugin to read the customized captures saved by our tool.

Capture files are automatically saved in folder logs/Bluetooth/capture_bluetooth.pcapng. To open it via the custom Wireshark, run the following on the root folder of the exploiter (bin folder must be present on your working directory):

./bin/wireshark logs/Bluetooth/capture_bluetooth.pcapng

You should see the following if the capture file was generated correctly:

Advanced BT Options

The exploiter BT options are loaded from configs/bt_config.json on the following attributes:

{
    "config": {
        "Bluetooth": {
            // BT Options
            "EnableBounding": true,
            "AuthReq": 4,        
            "DisableRoleSwitch": true,
            "IOCap": 3,
            "Pin": "0000",
            "TargetBDAddress": "E0:D4:E8:19:C7:69",
            // TODO: Store a list of targets
            "TargetBDAddressList": [  
                "24:0A:C4:61:1C:1A",
                "E0:D4:E8:19:C7:69"
            ]
            // ...
     }
  // ...
}

• Save Captures - When option is enabled, capture file is saved on logs/Bluetooth/capture_bluetooth.pcapng

• Scan - Scan for BT targets

• BT Program - Programs or "Profiles" which connect with a target device or wait for a connection. The available BT programs are available on the table below:

  BT Program	Connection Type	PROFILE
  bin/sdp_rfcomm_query	Initiator / Master	SDP / RFCOMM

• Target BDADDR - Target of the device to connect. Only applied for BT programs which initiates the connection. This is not applied for programs that wait for connections such as bin/spp_counter or bin/a2dp_sink_demo.

Security Options

• Enable Bounding - Enabled BT Pairing. If disabled, then all the next options have no effect.
• Disable Role Switch (Checkbox) - Forces connection to reject any attempts to perform role switching. This ensures that once the master connects to a slave, their roles stay the same during the session. Exploits such as KNOB require this for the master (being the fuzzer) to mutate the LMP_max_encryption_key_size_req packet. Disable this options if the slave does not accept the connection without role switching.
• IO Capabilities - Selects IO capabilities of the fuzzer during the pairing process according to the following:
  • Display Only = 0
  • Display Yes No = 1
  • Keyboard Only = 2
  • No Input No Output = 3 (Default)
  • Unknown = 256
• Auth. Requirements - Flag which indicates the authentication parameters during the pairing process.
  • No MitM, No Bouding = 0
  • MitM, No Bouding = 1
  • No MitM, Dedicated Bouding = 2
  • MitM, Dedicated Bouding = 3
  • No MitM, General Bouding = 4
  • MitM, General Bouding = 5
• PIN - 4 digit PIN number to be used during pairing (legacy pairing method).

Acknowledgement

This research was partially supported by NRF National Satellite of Excellence in Trustworthy Software Systems (Project no. RGNSOE2001 and RGNSOE2101).