[NEWS] Car Whisperer

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  Car Whisperer
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SUMMARY

The carwhisperer project intends to educates manufacturers of carkits and 
other Bluetooth appliances to the possibility of a security threat caused 
by the use of standard passkeys.

DETAILS

A Bluetooth passkey is used within the pairing process that takes place, 
when two Bluetooth enabled devices connect for the first time. Besides 
other public data, the passkey is a secret parameter used in the process 
that generates and exchanges the so-called link key. In Bluetooth 
communication scenarios the link key is used for authentication and 
encryption of the information that is exchanged between the counterparts 
of the communication.

The cw_scanner script repeatedly performs a device inquiry for visible 
Bluetooth devices of which the class matches the one of Bluetooth Headsets 
and Hands-Free Units. Once a visible Bluetooth device is found and it has 
the appropriate device class is found, the cw_scanner script executes the 
carwhisperer binary that connects to the found device (on RFCOMM channel 
1) and opens a control connection and connects the SCO links.

The carwhiperer binary connects to the device found by the cw_scanner. The 
passkey that is required for the initial connection to the device is 
provided by the cw_pin.pl script that replaces the official Bluez PIN 
helper (graphical application that usually prompts for the passkey). The 
cw_pin.pl script provides the passkey depending on the Bluetooth address 
that requests it. Depending on the first three bytes of the address, which 
references the manufacturer, different passkeys are returned by the 
cw_pin.sh script. In quite a few cases the preset standard passkey on 
headsets and handsfree units is '0000' or '1234'.

Once the connection has been successfully established, the carwhisperer 
binary starts sending audio to, and recording audio from the headset. This 
allows attackers to inject audio data into the car. This could be fake 
traffic announcements or nice words. Attackers are also able to eavesdrop 
conversations among people sitting in the car.

Ideally, the carwhisperer is used with a toooned dongle and a directional 
antenna that enhances the range of a Bluetooth radio quite a bit. (see 
Long-Distance-Snarf experiment)

Recommendations:
In order to avoid getting attacked by carwhisperer, manufacturers should 
not use standard passkeys in their Bluetooth appliances. Moreover, there 
should be some kind of direct interaction with the device that allows a 
device to connect. Another recommendation would be to switch the handsfree 
unit to invisible mode, when no authorized device connects to it within a 
certain time.

Not all Bluetooth carkits are subject to this threat. There is quite a few 
Bluetooth carkits that use random passkeys that are generated for every 
individual device during the production process. Carkits that are 
integrated with a full infotainment system could use (and sometimes 
already do use) the infotainment system's UI for acquiring a passkey from 
the user.

Proof of Concept:
A proof of concept can be found at:  
<http://trifinite.org/Downloads/carwhisperer-0.1.tar.gz> 
http://trifinite.org/Downloads/carwhisperer-0.1.tar.gz


ADDITIONAL INFORMATION

The information has been provided by  <mailto:[email protected]> 
Juha-Matti Laurio .
The review was written by  <mailto:[email protected]> Martin Herfurt.
The original article can be found at:  
<http://trifinite.org/trifinite_stuff_carwhisperer.html> 
http://trifinite.org/trifinite_stuff_carwhisperer.html



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