Can Hardware Wallets Really Be Hacked? The Coldcard Vulnerability Raises New Security Questions

The disclosure made by Kraken Security Labs in February 2023 exposed a physical vulnerability in the Coldcard Mk4 that enables seed extraction without knowing the PIN. The finding reignited a technical discussion that the crypto sector tends to avoid: no hardware wallet is immune to a physical attack with sufficient resources. The documented exploit does not represent a product failure, but rather an empirical confirmation of the limits that physical reality imposes on any embedded security system.

The attack focused on the dual-chip architecture that distinguishes the Mk4. The main microcontroller, an STM32, stores the seed encrypted with a secret key safeguarded in the ATECC608A secure element. This secure element was designed to release the key only after verifying the PIN. Kraken’s team applied voltage fault injection —a technique known as voltage glitching— on the communication bus between the two chips at the exact moment the key traveled from the ATECC608A to the STM32. By disturbing the secure element’s operation at that critical instant, they forced it to deliver the key without having validated any PIN. With the key in their possession, they decrypted the seed stored in the microcontroller’s flash memory.

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