A new debate about security is brewing in the world of hardware crypto wallets. The Ledger Donjon research lab has disclosed details of a physical attack on popular Tangem NFC cards. The method, based on laser fault injection, allows an attacker to reset the card's password and gain full control over digital assets. This is a serious wake-up call for the industry, demonstrating that even certified chips do not guarantee absolute protection at the firmware level.
Technical Essence of the Vulnerability
Tangem hardware wallets are plastic cards with a secure Samsung S3D232A chip (EAL6+ certification). This chip is responsible for generating private keys and signing transactions. The standard security model involves two factors: physical possession of the card and knowledge of the password. However, as Ledger Donjon discovered, the logic of the SetPin instruction (password change) contains a critical vulnerability.
The firmware includes a check that only allows a password reset when two linked cards are present (recovery function). The researchers demonstrated that a single nanosecond laser pulse directed at a specific area of the chip can disrupt this check. As a result, the card accepts a new password without entering the old one and without a backup. After this, the attacker can sign any transactions and withdraw funds.
Practical Implementation and Attack Cost
It is important to emphasize: this attack is not a remote hack. It requires physical access to the card, opening it, and connecting it to specialized equipment. Preparation involves exposing the chip, conducting side-channel analysis to precisely determine the moment the vulnerable check is executed, and then directing the laser pulse. The cost of a laboratory setup is estimated at approximately $250,000, not including the necessary expertise in hardware security. After configuring parameters for a specific model, each exploitation attempt takes about two hours.
Tangem's Response and My Assessment
Tangem, naturally, hastened to state that the risk for ordinary users is "practically non-existent," citing the high cost of equipment and the need for physical access. They also noted that Ledger Donjon is a division of their direct competitor. This is a logical but incomplete argument. Yes, there will be no mass "script-kiddie" style hacks. However, for holders of large sums or institutional investors, this threat vector is real.
The main takeaway from this story is not that Tangem is bad. It is that EAL6+ certification confirms the chip's protection against hardware attacks but does not guarantee the correctness of the firmware logic running on top of it. This is a classic "strong door, weak lock" problem. Ledger Donjon brilliantly demonstrated that software logic on secure elements requires the same thorough auditing as smart contracts.
My professional opinion: For 99.9% of Tangem users, this vulnerability does not pose an immediate threat — your card is safe as long as it is in your hands. But for those storing significant assets who have experienced card loss or theft, this is a reason to consider diversification: using multiple wallets from different manufacturers or adding multisig. The hardware wallet market must evolve towards deeper firmware testing, not just hardware.