The Ledger Donjon research group, specializing in hardware security, has identified a critical vulnerability in Tangem hardware wallets. The method, based on laser fault injection, allows an attacker to reset the card's PIN code and gain full control over the crypto assets stored on it.
Tangem produces wallets in the form of NFC cards resembling bank cards. Inside each card, a secure Samsung S3D232A chip with EAL6+ certification is installed, responsible for generating private keys and signing transactions. Communication with the mobile app occurs via NFC. According to my analysis, the vulnerability affects all Tangem cards currently in circulation and cannot be fixed with a firmware update, as the devices do not support such a feature.
Technical Details of the Attack
Typically, access to funds is protected by two factors: physical possession of the card and knowledge of the password. Tangem also implements a recovery mechanism via two linked cards. Ledger Donjon researchers focused on the logic of the SetPin instruction used when changing the password. The firmware includes a check that only allows changes in a specific recovery state. Laser fault injection can bypass this check, forcing the card to accept a new password without entering the old one and without using the backup card.
To carry out the attack, the card's casing must be opened to expose the secure element. Then, using side-channel analysis, the exact moment of the vulnerable check's execution is determined. After that, a nanosecond laser pulse is directed at a specific area of the chip associated with the instruction execution logic. After successfully resetting the password, the attacker can sign transactions and withdraw funds.
However, this attack is not for the average hacker. Ledger Donjon estimates the cost of the necessary laboratory equipment at approximately $250,000. Additionally, tools for side-channel analysis, deep knowledge of hardware security, and preparation time are required. Each new exploitation attempt, after configuring parameters for a specific card model, takes about two hours.
Tangem's Response and Expert Analysis
Tangem stated that the risk for ordinary users is "practically negligible," emphasizing the need for physical access to the card and expensive equipment. The company also noted that Ledger Donjon, while positioning itself as an independent research unit, operates within Ledger—one of Tangem's main competitors.
Nevertheless, I believe this discovery is an important signal for the entire industry. It demonstrates that even EAL6+ certification, confirming the hardware's resilience, does not guarantee the security of the software logic running on top of the chip. As the researcher rightly pointed out, software on such chips must be developed with special protection patterns, including multiple independent checks for critical operations and more robust state encoding.