peku33 peku33 - 1 month ago 30
Android Question

Sniffing/logging your own Android Bluetooth traffic

I recently bought chinesse device that connects via bluetooth with android phone / tablet. Since there is no application availible for windows / linux I want to create one for personal usage.

Usually phone connects to the device and exchanges some data. I connected PC to the device and looked into serial debugger and menaged to discover the protocol (one way only). Phone sends only one command to the device. But this time I'm not able to find out what it containts.

Is there any software that will allow me to look into data sent via bluetooth? I tried decompiling the app, but it looks really unfriendly.

Thanks.

Answer

Android 4.4 (Kit Kat) does have a new sniffing capability for Bluetooth. You should give it a try.

If you don’t own a sniffing device however, you aren’t necessarily out of luck. In many cases we can obtain positive results with a new feature introduced in Android 4.4: the ability to capture all Bluetooth HCI packets and save them to a file.

When the Analyst has finished populating the capture file by running the application being tested, he can pull the file generated by Android into the external storage of the device and analyze it (with Wireshark, for example).

Once this setting is activated, Android will save the packet capture to /sdcard/btsnoop_hci.log to be pulled by the analyst and inspected.

Type the following in case /sdcard/ is not the right path on your particular device:

adb shell echo \$EXTERNAL_STORAGE

We can then open a shell and pull the file: $adb pull /sdcard/btsnoop_hci.log and inspect it with Wireshark, just like a PCAP collected by sniffing WiFi traffic for example, so it is very simple and well supported:

screenshot of wireshark capture using Android HCI Snoop

[source]

You can enable this by going to Settings->Developer Options, then checking the box next to "Bluetooth HCI Snoop Log."