My analytical team conducted a detailed investigation of a recently discovered hardware vulnerability in Tangem wallet cards. This concerns a critical attack vector that allows an attacker with physical access to the card to completely reset the password and gain control over all associated digital assets.
What is the essence of the problem
Tangem wallets are designed in the form factor of a bank card and are equipped with a secure Samsung chip certified to EAL6+. This chip is responsible for generating and storing keys, as well as signing transactions. The master key never leaves the card, and access is protected by two-factor authentication: physical possession of the card and knowledge of the PIN code.
The weak link turned out to be the password recovery logic. Cards are sold in sets of two or three with a shared master key. The standard mechanism allows resetting the password if two linked cards are available. However, it turned out that this very function contains a vulnerability. The attack aims to bypass the check of whether the card is in recovery mode. If so, a new password is accepted without the old one. The attacker's task is to "break" this single check, forcing the card to accept a new password without actually being in recovery mode.
Compounding the issue, the password change command has no protection against brute force. Unlike authentication commands, it does not introduce delays or lockouts after failed attempts. This allows the attacker to try repeatedly until the correct password is found.
Technical implementation of the attack
The attack method is laser fault injection. It involves directing a powerful pulse of infrared light at a specific point on the chip's die at a precise moment of operation. This temporarily alters the state of the transistors and disrupts the program flow, bypassing the required check.
To carry out the attack, the plastic casing of the card must be opened with a scalpel, the protective shield removed to expose the silicon die, and the antenna resoldered for stable power. According to my data, on a prepared model, the attack achieved 100% reproducibility, with each attempt taking about two hours.
Notably, disabling the password recovery function in the settings does not help. This setting only blocks one of the legitimate recovery commands, whereas the attack itself does not use it but directly targets the state check.
Conclusions and recommendations
There is no patch for this vulnerability. However, the key takeaway for users is that the attack requires physical access to the card, specialized laboratory equipment costing around $250,000, and deep expertise in hardware security. It is impossible to carry it out discreetly and return the card untouched.
Real risk only arises if the card is lost or stolen. If it remains with the owner, the described scenario is not feasible. Nevertheless, this finding underscores the importance of physical security for hardware wallets and the need for continuous auditing of their protective mechanisms.
My expert opinion: This vulnerability is a serious wake-up call for the industry. Even certified chips with high levels of protection can have vulnerabilities at the application logic level. Tangem users should be especially careful about the physical security of their cards and consider using additional protective measures, such as multi-signature or separate key storage.