AVR-Glitch-101

The most basic introduction to performing a power glitch attack.

Author: Dean Jerkovich (https://github.com/deanjerkovich)

Author 2: Dhiru Kholia (https://github.com/kholia)

Intro

The basic idea here is to set up some inexpensive hardware and watch what happens when the power supply into the AVR (on the Arduino) is intentionally interrupted. Some simple code that performs arithmetic is loaded on to the AVR and it communicates back to the host computer over serial. The ground wire to the AVR is running via a transistor which is switchable by an FPGA. The FPGA has a simple piece of verilog which drops an output to 0 for a small number of clock ticks every 20 million or so clock ticks (a bit over a second of time, given the 12MHz clock). The net effect is that the AVR loses power for very small factions of time, causing noticable disruptions in arithmetic and logic without triggering the brown-out detection or causing a full reset.

Requirements

• An iCEstick / iCEBreaker / TinyFPGA BX FPGA board.

• An Arduino Uno target board (see sparkfun) and Arduino IDE

• Some connecting wires, 2N7000 MOSFET (TO-92 package for ease of use), 1k resistor (0.25W is fine)

  • FPGA's ground pin is connected to 2N7000's source (Pin 1)

  • FPGA's glitch output pin is connected to 2N7000's gate (Pin 2)

  • 2N7000's drain (Pin 3) is connected to the target's ground pin

  Note: 2N7000 and BS170 are non-RF MOSFETS but they are used widely in amateur RF applications (HF operations up to 30 MHz). They should be good enough for our low-current-usage purposes, especially the BS170.

  For higher-current applications, IRLZ44 should suffice.

• https://github.com/open-tool-forge/summon-fpga-tools - script to install open-source FPGA toolchains

Wiring it up

See the blog post.

Results

Solving the avr-glitch-101 challenge:

Solving the Rhme2 challenge (2016) - Fiesta challenge:

The Differential Fault Injection Against AES challenge:

w00t!

Note: We use our same GND glitching hardware setup for this DFI attack against AES. This is different, and simpler from the upstream's approach.

References

• https://flawed.net.nz/2017/01/29/avr-glitch-modifying-code-execution-paths-using-only-voltage/

• https://blog.securitybits.io/2019/06/voltage-glitching-on-the-cheap/

• https://rot256.dev/post/glitch/

• https://github.com/kholia/aes-atmega328-glitching (fork)

• https://github.com/rot256/aes-atmega328-glitching (upstream)

• https://itooktheredpill.irgendwo.org/2020/stm8-readout-protection/

• https://blog.securitybits.io/2019/06/voltage-glitching-on-the-cheap/

• https://github.com/kholia/PicoGlitcher (fork)

• https://deralchemist.wordpress.com/2021/05/28/raspberry-pico-voltage-glitcher/