Ledger Donjon's research division has identified a serious vulnerability in Tangem hardware wallets. Using laser fault injection, an attacker with physical access to the storage card can reset the password and gain full control over all associated digital assets.
Tangem wallets, which resemble ordinary bank cards, use a secure Samsung chip with EAL6+ certification. This chip is 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.
Achilles' Heel: Password Recovery Logic
The weak link, as experts discovered, 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. The problem is that the check to determine whether a card is in recovery mode proved vulnerable to attack. The attacker's goal is to "break" this single check, tricking the card into accepting a new password without actually being in recovery mode.
Compounding the issue, the password change command lacks protection against brute force. Unlike authentication commands, it does not introduce delays or lockouts after failed attempts, allowing repeated tries.
Attack Method: Laser Fault Injection
The attack itself is technically complex and invasive. Researchers opened the plastic card casing with a scalpel, removed the protective shield to expose the chip's silicon die, and then re-soldered the antenna for stable power.
The primary 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 transistor states and disrupting the program flow. In this case, it allows bypassing the required check.
A separate challenge was the chip's own protection. When tampering was detected, the chip would write data to flash memory, and after approximately 256 such events, the cards would become permanently inoperable. To bypass this, the team learned to monitor writes in real time and cut power before completion.
Threat Scope and Recommendations
According to Ledger Donjon, disabling the password recovery function does not help. This setting only blocks one of the legitimate recovery commands, whereas the attack does not use it but instead directly targets the state check.
The key takeaway for users: there is no patch, but the danger is real. The attack requires physical access to the card, specialized laboratory equipment costing around $250,000, and deep expertise in hardware security. On a prepared model, it achieved 100% reproducibility, with each new attempt taking about two hours. Real risk arises only if the card is lost or stolen; if it remains with the owner, the described scenario is impossible.
My expert opinion: This finding is a vivid example that even top-tier certified chips do not guarantee absolute protection against physical attacks. For the average user, the risk is minimal, but the incident underscores the importance of physical device security and reminds us that "cold storage" is not just a technology but also a practice.