Critical Tangem vulnerability: laser attack resets password and empties wallet
Ledger Donjon's research unit has identified a critical vulnerability in Tangem hardware wallets. An attack using a powerful laser allows an attacker with physical access to the storage card to reset the set password and gain full control over all digital assets associated with it.
What is the essence of the vulnerability
Tangem wallets externally resemble ordinary bank cards. Inside, they contain a secure Samsung chip with EAL6+ certification, responsible for generating and storing keys, as well as signing transactions. The master key never leaves the card, and access to funds is protected by two factors: physical possession of the card and knowledge of the password. However, as experts discovered, a critical flaw is hidden in the password recovery logic.
The cards are sold in sets of two or three with a shared master key. The standard recovery mechanism allows resetting the password if two linked cards are available. The problem is that the only check in this process is whether the card is in recovery mode. If so, a new password is accepted without entering the old one. The goal of the attack is to "break" this check, forcing the card to accept a new password outside of the actual recovery mode.
Compounding the issue is that the password change command lacks protection against brute force. Unlike authentication commands, it does not introduce delays or lockouts after failed attempts. This allows an attacker to try repeatedly without fear of being locked out. After resetting the password, the attacker gains full control: they can sign any transactions and withdraw all funds associated with the card.
How the attack is carried out and what it means
The attack itself is technically complex and invasive. Researchers opened the plastic card casing with a scalpel, removed the protective shield, exposed the chip's silicon die, and resoldered the antenna for stable power. The main method was laser fault injection. A powerful pulse of infrared light is directed at a specific point on the die at a precise moment of operation, temporarily altering the state of transistors and disrupting the program's flow—in this case, bypassing the necessary check.
A separate issue was the chip's own protection. When tampering was detected, the chip wrote data to flash memory, and after approximately 256 such events, the cards would fail irrecoverably. To bypass this, the team learned to monitor the writing in real-time and cut power before it completed.
Key takeaway: there is no patch, and the danger is real. The attack cannot be carried out unnoticed, and the card cannot be returned untouched. Real risk only arises if the card is lost or stolen. If it remains with the owner, the described scenario is impossible.
My expertise: this finding is yet another reminder that even the most secure hardware wallets are not absolutely invulnerable. Given the high cost of equipment (~$250,000) and the need for deep expertise, a mass attack is unlikely. However, for owners of large sums, this is a reason to reconsider storage strategy: diversifying assets across multiple devices from different manufacturers remains the gold standard of security. I would recommend Tangem users, especially those with significant portfolios, to consider moving funds to wallets with a more transparent security architecture or using multi-signature.