Trezor Safe devices still vulnerable to physical supply chain attacks, Ledger says

Trezor’s latest hardware wallets feature secure elements but are still vulnerable to attacks targeting their microcontrollers, Ledger claims.

In the constantly shifting world of crypto security, even the most advanced hardware wallets aren’t immune to emerging threats.

Now, cybersecurity experts at Ledger Donjon, the research arm of physical crypto wallet Ledger, are raising concerns about its rival Trezor. Despite its reputation for secure design, Trezor’s Safe models appear vulnerable to physical attacks. While the devices feature dual-chip setups and certified secure elements, researchers at Ledger argue that these models aren’t fully protected against determined hackers.

In a March 12 blog post, Ledger notes that the new Trezor Safe devices were designed with better security features, including a two-chip setup with a certified Secure Element (Optiga Trust M) for storing PINs and cryptographic secrets. Yet, Ledger says critical cryptographic operations “are still performed on a microcontroller however,” which makes attacks in more “advanced threat models possible.”

“The microcontroller used is labeled TRZ32F429 – this is actually a STM32F429 chip packaged into a BGA with custom markings. In spite of the Trezor-specific package however, it is really electrically the same as a STM32F429, and this chip’s family is known to be vulnerable to voltage glitching, enabling read and write access to its flash contents.”

Ledger

While the devices include mechanisms to prevent tampering, Ledger believes these defenses are not foolproof, stating that it is only “a matter of time and engineering effort to pull off the attack in practice.” Most importantly, the researchers argue that the attack can be executed “purely in software,” making it “very hard, if not impossible,” to detect either cryptographically or through visual inspection.

Despite these risks, Trezor Safe devices are considered a step forward in crypto hardware security, Ledger admits, though emphasizes that continued vigilance is needed to address potential weaknesses in the supply chain.

Following the publication of the research, Trezor’s X account reassured users that their funds “remain safe,” noting that Ledger Donjon had reused a “previously known attack to bypass some of our countermeasures against supply chain attacks in Trezor Safe 3.”