Ledger Donjon's research unit has identified a serious physical vulnerability in Tangem hardware cryptocurrency wallets. The attack, based on laser fault injection, allows an attacker to reset the card's password and gain full control over the assets stored on the device. This discovery calls into question the security of even the most seemingly protected solutions.
Technical Details of the Attack
Inside the Tangem wallet, designed as an NFC card, a Samsung S3D232A secure element with EAL6+ certification is used. Typically, access to funds is protected by two factors: physical possession of the card and knowledge of the password. The vulnerability lies in the logic of the SetPin instruction, responsible for changing the password. The firmware includes a check that only allows a reset if a backup card is present. A laser pulse directed at a specific area of the chip disrupts this check, forcing the card to accept a new password without any additional conditions.
To carry out the attack, the researcher had to open the card's casing, expose the secure element, and connect it to their own hardware platform. Using side-channel analysis, the exact moment of the check's execution was determined. Subsequently, a single nanosecond laser pulse aimed at the chip area responsible for the instruction execution logic successfully bypassed the protection. After resetting the password, an attacker can sign transactions and withdraw funds.
Practical Implementation and Risks
It is important to emphasize that the attack is physical and invasive. It cannot be carried out covertly, and the card remains damaged afterward. The only realistic risk scenario is the loss or theft of the card. If the device is in the owner's possession, the attack is impossible. Furthermore, the cost of equipment required for such an attack is estimated at approximately $250,000, and it requires a high level of expertise in hardware security. Preparing and exploiting the vulnerability for a specific model takes about two hours.
Tangem's Response and Conclusions
Tangem representatives described the risk for ordinary users as "practically non-existent," citing the need for physical access to the card, expensive laboratory equipment, and expertise. They also noted that Ledger Donjon is a division of their direct competitor, which could influence the interpretation of the results. In any case, the incident highlights the limitations of EAL6+ certification: it confirms the chip's robustness but does not guarantee the absence of vulnerabilities in the software logic running on top of it.
My professional opinion: This attack is a brilliant example of how even the most reliable hardware platform can be compromised due to a firmware error. It is a reminder that security is not a static certificate but a continuous process. Tangem urgently needs to review the security architecture of its cards and possibly release a new version with hardware protection against such injections, as current devices cannot have their firmware updated. For users, I recommend being extremely vigilant about the physical security of their cards.