Fault Injection
What Is Fault Injection?
Most computer systems are designed to operate within strict environmental parameters. Fault injection tries to push a device outside those limits using techniques such as precise spikes in voltage, extreme temperature changes, or high-powered lasers while a security check is occurring.
The goal is to induce a glitch that causes the system to skip a step, misread data, or produce an error that reveals secret information.
Think of a high-security door that requires a keycard. A logical attack would be trying to clone the card. A fault injection attack would try to disrupt the door’s control electronics at the exact moment it checks the card.
How Does Fault Injection Work?
Common methods include:
- Voltage Glitching: Briefly dropping or spiking the power supply to a chip. This can cause the processor to skip specific instructions in its code.
- Clock Glitching: Interfering with the internal timer that tells a chip when to execute the next step. By speeding up the clock for a fraction of a second, an attacker can force the chip to skip critical security checks.
- Laser Fault Injection (LFI): Using a high-precision laser to hit a specific transistor on a microscopic level. This can flip a single bit or corrupt data.
- Electromagnetic Fault Injection (EMFI): Using a small coil to create a localized magnetic field near the chip, inducing electrical currents that disrupt its normal operation.
The Donjon: Hardening the Ecosystem Against Physical Attacks
Fault injection is one important research method used by the Ledger Donjon. As Ledger’s internal team of white-hat hackers, the Donjon uses state-of-the-art laboratory equipment to stress-test hardware and software across the entire crypto ecosystem. By proactively finding these physical weaknesses in third-party components and industry-standard infrastructure, the Donjon helps identify weaknesses and improve resilience against attackers.
