Injecting Bugs With An Electric Flyswatter

Hardware fault injection uses electrical manipulation of a digital circuit to intentionally introduce errors, which can be used to cause processors to behave in unpredictable ways. This unintentional behavior can be used to test for reliability, or it can be used for more nefarious purposes such as accessing code and data that was intended to be inaccessible. There are a few ways to accomplish this, and electromagnetic fault injection uses a localized electromagnetic pulse to flip bits inside a processor. The pulse induces a voltage in the processor’s circuits, causing bits to flip and often leading to unintentional behavior. The hardware to do this is very specialized, but [Pedro Javier] managed to hack a $4 electric flyswatter into an electromagnetic fault injection tool. (Page may be dead, try the Internet Archive version.)

[Pedro] accomplishes this by turning an electric flyswatter into a spark-gap triggered EMP generator. He removes the business end of the flyswatter and replaces it with a hand-wound inductor in series with a small spark gap. Pressing the power button on the modified flyswatter charges up the output capacitor until the developed voltage is enough to ionize the air in the spark gap, at which point the capacitor discharges through the inductor. The size of the spark gap determines the charge that is built up—a larger gap results in a larger charge, which produces a larger pulse, which induces a larger voltage in the chip.

[Pedro] demonstrates how this can be used to produce arithmetic glitches and even induce an Arduino to dump its memory. Others have used electromagnetic fault injection to corrupt SRAM, and intentionally glitching the power supply pins can also be used to access otherwise protected data.

The ChipWhisperer At Defcon

We’ve seen [Colin]’s entry to The Hackaday Prize before. After seeing his lightning talk at Defcon, we had to get an interview with him going over the intricacies of this very impressive piece of hardware.

The ChipWhisperer is a security and research platform for embedded devices that exploits the fact that all security measures must run on real hardware. If you glitch a clock when a microcontroller is processing an instruction, there’s a good probability something will go wrong. If you’re very good at what you do, you can simply route around the code that makes up the important bits of a security system. Power analysis is another trick up the ChipWhisperer’s sleeve, analyzing the power consumption of a microcontroller when it’s running a bit of code to glean a little information on the keys required to access the system. It’s black magic and dark arts, but it does work, and it’s a real threat to embedded security that hasn’t had an open source toolset before now.

Before our interview, [Colin] did a few short and sweet demos of the ChipWhisperer. They were extraordinarily simple demos; glitching the clock when a microcontroller was iterating through nested loops resulted in what can only be described as ‘counter weirdness’. More advanced applications of the ChipWhisperer can supposedly break perfectly implemented security, something we’re sure [Colin] is saving for a followup video.

You can check out [Colin]’s 2-minute video for his Hackaday Prize entry below.

Continue reading “The ChipWhisperer At Defcon”

THP Entry: Embedded Hardware Security With The ChipWhisperer


There are thousands upon thousands of papers discussing various aspects of embedded hardware security, and dozens of books covering the same subject. The attacks discussed in the literature are very cool – things like side-channel power analysis and clock glitching used to extract keys from a system. The experimental setups in these papers are extraordinarily expensive – you can buy a new car for less. [coflynn] was disheartened with the price of these tools, and thought building his own would make for a great entry to The Hackaday Prize.

The hardware part of the ChipWhisperer includes a breakout board with an FPGA, ADC, and connectors for a lot of different probes, adapters, breakout boards, and a target board, With all these tools, it’s not unreasonable to say that [coflynn] could carry out a power analysis attack on a lot of embedded hardware.

Open source hardware is just one part of this entry. The biggest focus of this project is the open source software for analyzing whatever the probes and target boards record. With this software, anyone can monitor the power used when a chip runs a cryptographic function, or glitch a clock for some unintended functionality in a device. In keeping with the academic pedigree of all the literature on these attacks, there are a ton of tutorials for the ChipWhisperer for all those budding security researchers out there. Very cool stuff, and arguably one of the most technical entries to The Hackaday Prize.

Video below.

SpaceWrencherThe project featured in this post is an entry in The Hackaday Prize. Build something awesome and win a trip to space or hundreds of other prizes.

Continue reading “THP Entry: Embedded Hardware Security With The ChipWhisperer”