Trezor One and Model T wallets found with microcontroller implants generating attacker-known seed phrases, sold via unauthorized sellers
Hardware hacker Joe Grand found tampered Trezor Model T and Trezor One wallets sold through unauthorized third-party channels (Facebook Marketplace in Canada in 2025, and a TikTok shop in August 2026, shipped from China). The attackers replaced the microcontroller with one running malicious firmware that hands users one of about a dozen pre-determined recovery seed phrases, so the attackers can later drain the accounts. One Trezor One owner lost about $50 before becoming suspicious. Grand notified Trezor about the Model T on August 10, yet Trezor publicly claimed there was no evidence of compromised devices while cutting its list of authorized resellers. The case matters because the earlier Ledger implants, tied to roughly $100 million in stolen crypto, also began in unauthorized channels before appearing in devices from authorized resellers.
Technical Details
- The legitimate microcontrollers have code-protection features, but because Trezor firmware is open source, the attackers modified it and flashed it onto unprotected replacement chips.
- The malicious firmware "generates" one of several seed phrases known to the attackers and shows it to the user as if it were random.
- To pass firmware integrity checks, the Model T carries legitimate firmware on an external microSD card soldered to the internal connector. The Trezor One uses a chip marked STM32F205RET6 (512KB Flash) that actually holds 1MB, half malicious and half official firmware used for the integrity check.
- This differs from the Ledger implants, which passively record the seed phrase at first initialization and exfiltrate it over a cell tower connection.
- Trezor says the Trezor Suite entropy check should detect such devices and that the case is a variant of the 2022-2023 modified devices Kaspersky found on Russian marketplaces. Grand disputes this: the Trezor One unit is flagged by the latest Trezor Suite, but the software lets the user keep using it, and Trezor's own team called the Model T a "particularly interesting variation".
- Trezor stopped selling these models on 8 January 2026 and says there is no known way to use this attack on current Safe devices.
Remediation
- Buy hardware wallets only from the vendor's website or authorized resellers, never from marketplaces or social media shops.
- Treat any Trezor Suite entropy or integrity warning as a stop signal, and do not fund the wallet.
- Trezor is reducing its authorized resellers and tightening sourcing, storage and handling checks for the remaining ones.
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Trezor One and Model T wallets found with microcontroller implants generating attacker-known seed phrases, sold via unauthorized sellers
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Hardware hacker Joe Grand found tampered Trezor Model T and Trezor One wallets sold through unauthorized third-party channels (Facebook Marketplace in Canada in 2025, and a TikTok shop in August 2026, shipped from China). The attackers replaced the microcontroller with one running malicious firmware that hands users one of about a dozen pre-determined recovery seed phrases, so the attackers can later drain the accounts. One Trezor One owner lost about $50 before becoming suspicious. Grand notified Trezor about the Model T on August 10, yet Trezor publicly claimed there was no evidence of compromised devices while cutting its list of authorized resellers. The case matters because the earlier Ledger implants, tied to roughly $100 million in stolen crypto, also began in unauthorized channels before appearing in devices from authorized resellers.
Technical Details
- The legitimate microcontrollers have code-protection features, but because Trezor firmware is open source, the attackers modified it and flashed it onto unprotected replacement chips.
- The malicious firmware "generates" one of several seed phrases known to the attackers and shows it to the user as if it were random.
- To pass firmware integrity checks, the Model T carries legitimate firmware on an external microSD card soldered to the internal connector. The Trezor One uses a chip marked STM32F205RET6 (512KB Flash) that actually holds 1MB, half malicious and half official firmware used for the integrity check.
- This differs from the Ledger implants, which passively record the seed phrase at first initialization and exfiltrate it over a cell tower connection.
- Trezor says the Trezor Suite entropy check should detect such devices and that the case is a variant of the 2022-2023 modified devices Kaspersky found on Russian marketplaces. Grand disputes this: the Trezor One unit is flagged by the latest Trezor Suite, but the software lets the user keep using it, and Trezor's own team called the Model T a "particularly interesting variation".
- Trezor stopped selling these models on 8 January 2026 and says there is no known way to use this attack on current Safe devices.
Remediation
- Buy hardware wallets only from the vendor's website or authorized resellers, never from marketplaces or social media shops.
- Treat any Trezor Suite entropy or integrity warning as a stop signal, and do not fund the wallet.
- Trezor is reducing its authorized resellers and tightening sourcing, storage and handling checks for the remaining ones.