During my participation in the DragonJAR conference as speaker, I had the opportunity to play with the PortaPack device during my trip. This beautiful device is a perfect add-on to my HackRF. Imaging that you have all the powerful features of the HackRF hardware and now add portability!

I updated the PortaPack and HackRF firmware. For the PortaPack, I used the impressive and beautiful Havoc version.

As security researcher, I was wondering if it was posible to use the PortaPack for a replay attack using tokenized NFC card or mag-stripe information to make a transaction. Basically, the idea was to implement somehow this device to achieved that purpose.

To understand properly how to generate Audio Spoof and how it works, we should take a look at previous posts:


To read some data directly from the PortaPack, I had to create a magnetic stripe radio station to transmit the signal using a FM transmitter. At this point, I had two choices: The Elechouse FM transmitter or the Zus universal car adapter:

The connection was straightforward. I decided to use the Zus FM transmitter, so I implemented a Bluetooth connection from my laptop to the device:

After this, I was able to play a WAV file to be transmitted by Bluetooth and see if I can receive something in the PortaPack listening mode. The best way to do it is using a waterfall view:

To generate a magnetic field using this WAV encoding, I had to add a coil in the jack output of the PortaPack:

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For the mag-stripe audio generation part, I had two options. One was the AudioSpoof repository or the ViolentMag code. I decided to use the ViolentMag with a few changes in the original mag-stripe recommendation.

Normally, we can create mag-stripe audio files with 25 leading zeros:

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Screen Shot 2018-10-02 at 12.52.05 AM

But to have better results and avoid noise in the initial part of the receiving, I decided to use 100 leading zeros in the WAV generation:

Screen Shot 2018-10-02 at 12.59.32 AM

Now, I just added a special coil in the jack output of the PortaPack; so it generates a magnetic field following the WAV file encoding which is detect by the card reader. Testing everything together:

With a few changes, this project could be implemented in Arduino, for example.