Cryptocurrency users face a fundamental challenge when securing their digital assets through hardware wallets: they cannot realistically detect sophisticated physical tampering, according to security researcher Joe Grand, who specializes in hardware security and has developed techniques to extract data from wallet memory chips.
The concern gained prominence after malicious implants were discovered in Ledger devices sold through CryptoBilis, an authorized reseller in Indonesia, Malaysia, and the Philippines. Ledger confirmed that at least one affected device contained an unauthorized implant that captured users' recovery phrases and transmitted them over cellular networks.
The Trust Problem
Hardware wallets are designed to keep private keys offline, reducing exposure to online attacks that target software-based alternatives. However, their distributed supply chains have created opportunities for tampering.
Crypto analyst Mati Greenspan noted that introducing a hardware wallet into a security strategy means accepting "a whole new chain of trust, from the manufacturer to the supplier to whoever handled the device before it reached you." Nick Neuman, CEO of Bitcoin security company Casa, acknowledged that avoiding third-party intermediaries entirely is impossible, recommending instead that users spread risk across multiple providers.
Current Protections Fall Short
Trezor, among Ledger's main competitors, stated that its devices undergo authenticity checks and accept only signed firmware. However, the company acknowledged these protections cannot rule out physical tampering. Visual inspections of packaging and device markings "cannot guarantee that it has not been modified," a Trezor spokesperson said.
Trezor noted that implants discovered in Ledger devices present a distinct challenge because they capture information from the screen without modifying firmware. The company has not observed this type of attack on its own devices.
In response to the incident, Trezor announced it would reduce its number of resellers as a preventive measure.
Potential Design Improvements
Grand suggested several physical design changes that could make supply-chain attacks more difficult, including transparent casings that expose internal components and tamper-resistant enclosures that would force attackers to recreate housing to conceal modifications. He referenced anti-tamper design recommendations from electronics engineer Dave Jones, while cautioning that such measures alone cannot eliminate tampering risks.
