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Reverse Engineering Black Box Systems with GreatFET, Troopers 2018

In this presentation at Troopers 2018, Kate Temkin and Dominic Spill used GreatFET One and the Facedancer software framework to demonstrate techniques for reverse engineering embedded USB hosts.

It is often fairly simple to set up an environment for reversing a USB device; you just plug it into a host that you control. Then you can manipulate software on the host to test or monitor USB communications between the host and device. Even if the host operating system doesn’t provide a way for you to monitor USB (hint: it probably does), you can run it inside a virtual machine that runs on top of Linux and use Linux’s usbmon capability.

But how do you sniff USB if the USB host is an embedded platform that you don’t control? What if it is a game console or a photocopier with software that you can’t run in a virtual machine? Kate and Dominic show how you can use GreatFET One and a laptop to proxy USB between a device and a host without controlling software on either the device or the host. With the USBProxy solution they implemented in Facedancer, it is possible not only to monitor USB communication but also to modify USB data in transit.

Additionally they demonstrate how the Facedancer software for GreatFET can be used to emulate a USB device, allowing them to reverse engineer “black box” USB hosts and test them for vulnerabilities.

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GreatFET on Hak5

I recently sat down with Darren Kitchen to record a couple Hak5 episodes. First we introduced GreatFET One to his viewers and demonstrated using its Facedancer capability to emulate a USB device. Then we did some infrared hacking with Gladiolus, a prototype GreatFET neighbor we plan to release later this year. Thanks for having me on the show, Darren!

Introducing the GreatFET One Hacking Infrared with Mike Ossmann and the GreatFET One


GreatFET One Has Arrived

It’s happenning! We started shipping GreatFET One to resellers last week, which means that very soon (probably even today) it will be available for you to order online from your favorite reseller of Great Scott Gadgets products. Hint: if your shop of choice doesn’t carry it yet, let them know you’re interested!

It was January of 2016 when Mike Ossmann gave his firetalk at Shmoocon titled GreatFET: A Preview, in which he explained how he bought the GoodFET project from Travis Goodspeed in a Las Vegas bar for $5. That was the beginning of the project that came to be known (humorously, at first) as GreatFET. At that time, GreatFET One was known as Azalea, and was still in the development stage. Three years and countless hours of engineering, development, and manufacturing effort later, we have completed the first production run.

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GreatFET One is a general purpose (and like all of our tools, open source) USB peripheral. When we say it’s general purpose, we mean that there are a whole lot of interesting things a hardware hacker, or maker, or tinkerer can customize it to do, especially through the addition of add-on boards called neighbors. But you don’t need to add anything on to start using this versatile this tool; there is plenty of USB hackery to be accomplished with GreatFET One on its own. Check out what Kate Temkin has been up to over the last year or so!

Very soon, we will also start offering a clear acrylic case and Daffodil, a solderless breadboard neighbour. To learn more about the GreatFET project and to see which resellers are already stocking GreatFET One, visit the GreatFET One product page.


Crème Brûlée Camp

We decided to go big at Toorcamp this year and make a jar of crème brûlée for every single person that attended. Delicious? Yes. Too ambitious? Maybe. Open source? You got it.

Image via Patch Eudor

Harnessing the power of GreatFET, we were able to connect a temperature sensor, LCD screen, and some bucket heaters, and cook up a very large amount of crème brûlée inside an average sized cooler while at camp, and it worked… but there were some rough spots. The problem wasn’t necessarily in the cooking process, but in the preparation stage: the cooler was able to fit 120 4oz jars in it for a batch, so someone needs to be cracking 120 eggs and separating the yolks, someone needs to be washing/drying 120 jars and lids from the factory, someone needs to mix the egg yolks, cream, vanilla, and sugar into a huge jug, someone needs to pour the right amount of mix into 120 jars, and someone needs to tighten 120 jar lids to the correct tightness, all while 10 gallons of water heats up in a cooler. Once all this is done, the batch can be placed into the cooking cooler for about seventy-five minutes. Finally, jars can be pulled from the cooking cooler to be sugared and brûlée’d by a person with a blow torch one at a time. Repeat.

As you can imagine, this takes a considerable amount of time and effort for just one batch of 120 jars. Not only that, but there unsurprisingly was not a 100% success rate, as some lids were not tight enough before being cooked and jars were cracked during the blowtorch brûlée phase. Doing this back to back for a few days was a ton of work. We were able to make 695 crème brûlées in one weekend, and everyone that wanted one got at least one! But for anyone thinking about trying this, be prepared to get your hands dirty.

If you want to learn about the R&D process you can check out the talk we gave at Toorcamp or if you’re interested in the source code and set-up, check it out on GitHub.