The world of hardware wallets is once again in the security spotlight. Researchers from the Ledger Donjon division have demonstrated a physical attack method on popular Tangem NFC cards using laser fault injection. This vector allows resetting the device's password and gaining full control over the digital assets stored on the chip.
Nature of the Vulnerability and Its Scope
Tangem produces hardware wallets in the form of plastic cards, inside which a secure element Samsung S3D232A with EAL6+ certification is installed. This chip is responsible for generating private keys and signing transactions. The standard security model assumes two factors: physical possession of the card and knowledge of the PIN code. However, it turns out that the software logic running on top of this chip has a critical flaw.
The vulnerability affects all issued Tangem cards and, critically, cannot be fixed through a firmware update — the devices simply do not support them. The attack focuses on the SetPin instruction, which is responsible for changing the password. Researchers found that the check allowing password reset only when a backup card is present can be bypassed.
Technical Details of the Attack
The method demonstrated by Ledger Donjon expert Baptiste Boileau involves several stages. First, the card is opened to gain access to the chip. Then, using side-channel analysis, the researcher determines the exact moment the vulnerable check is executed in the firmware. After that, a single nanosecond laser pulse is directed at a strictly defined area of the EAL6+ crystal, causing a fault in the execution logic and allowing a new password to be accepted without the old one or a backup card.
It is important to emphasize the invasive nature of the attack: it leaves physical damage, and the card cannot be restored to its original state. According to Ledger Donjon, after calibrating parameters for a specific model, each subsequent hacking attempt takes about two hours. However, the cost of the necessary equipment (laser setup, analysis tools) is estimated at around $250,000, making this vector accessible only to well-funded attackers.
Tangem's Response and Real Risks
Tangem called the threat to ordinary users "practically non-existent," emphasizing the need for physical access to the card and expensive laboratory equipment. The company also noted that Ledger is their direct competitor, hinting at possible bias in the research. Nevertheless, the very fact of demonstrating an attack on a certified EAL6+ chip raises an important question: certification of a secure element does not guarantee the absence of vulnerabilities in the software code running on it.
Ledger Donjon expert rightly pointed out that software development for such chips should be carried out using special protective templates. Recommendations include implementing multiple independent checks for critical operations and more robust state encoding.
My conclusion: This attack is a vivid example that even hardware wallets with the highest level of certification are not invulnerable. For 99.9% of Tangem users, the risk remains minimal, but investors with large sums should consider that the physical security of the device is only one layer of protection. The main lesson for the industry: trust in "hardware" should not be blind, and security must be multi-layered.