Joe Grand found swapped chips in two Trezor wallets that generated preset seed phrases
Joe Grand told Trezor in August that two of its wallets carried hardware implants, zetter-zeroday.com reports. Trezor's commercial chief has since written that there is no evidence of compromise as the company trims its authorized sellers.
The Watch · Security desk
Trezor One buyer: about $50 left his account. Third-party sellers sold both implanted wallets. Owners buy the discontinued models from third parties. Attackers put modified open-source code on their own chip. Trezor cuts authorized sellers; its CCO says no evidence of compromise.
- exposure Trezor One buyer Became suspicious when about $50 got transferred out of his crypto account, claim 3
- exposure Third-party sellers Nonauthorized sellers, not authorized ones, sold the implanted Trezor One and Model T, claim 8
- exposure Trezor One, Model T owners Discontinued models bought from third-party sellers; security updates run until 2036, claim 4
- capability Attackers Obtained the open-source code, modified it and put it on their own unsecured chip in place of the real one, claim 7
- decision Trezor Reducing the merchants authorized to sell its devices, out of an "abundance of caution", claim 14
- contradiction Danny Sanders, Trezor CCO Wrote there was "not a single piece of evidence" that Trezor devices have been compromised, claim 15
| Who | How | Kind | Claim |
|---|---|---|---|
| Trezor One buyer | Became suspicious when about $50 got transferred out of his crypto account | exposure | 3 |
| Third-party sellers | Nonauthorized sellers, not authorized ones, sold the implanted Trezor One and Model T | exposure | 8 |
| Trezor One, Model T owners | Discontinued models bought from third-party sellers; security updates run until 2036 | exposure | 4 |
| Attackers | Obtained the open-source code, modified it and put it on their own unsecured chip in place of the real one | capability | 7 |
| Trezor | Reducing the merchants authorized to sell its devices, out of an "abundance of caution" | decision | 14 |
| Danny Sanders, Trezor CCO | Wrote there was "not a single piece of evidence" that Trezor devices have been compromised | contradiction | 15 |
What happened
- Grand's Model T came from Facebook Marketplace in Canada some time in 2025, and his Trezor One came from a TikTok shop in August.
- The Trezor One buyer became suspicious when about $50 was transferred out of his crypto account.
- In both wallets the attackers replaced the microcontroller so it produced one of a dozen or so preset seed phrases instead of a random one.
- Because Trezor's firmware is open source, the attackers could obtain and modify it, then program it onto their own unsecured chip.
- About three years ago Kaspersky Lab found an implant in a Trezor wallet sold on a popular Russian marketplace.
Why it matters
- exposure Buyers of used Trezor One and Model T units carry the risk. Both models are discontinued but supported to 2036, so the secondary market for them has years to run.
- constraint Chip code protection, which Grand says exists to stop code changes, does not protect against a replaced chip.
- contradiction Sanders's blanket no-evidence line sits against Grand's August report. Both can hold only if the statement covers Trezor's own channel and nothing sold outside it.
- decision Trezor's authorized-seller list is now shorter, so a buyer has fewer vetted places to buy. Marketplace sellers sit outside any vetting.
In our view the limit on this attack is distribution. Each swapped unit hands the attacker a short list of candidate seeds, so the work per victim is small [5]. The hard part is getting the unit to a buyer, and in both of Grand's cases a third-party seller outside Trezor's authorized list did that [8].
Sanders's wording is categorical. He wrote that there was "not a single piece of evidence that Trezor devices have been compromised" [15]. The zetter-zeroday.com author answered that "this isn't exactly true," citing Grand's August notification [17][1]. The statement holds if "Trezor devices" means units sold through Trezor's own channel, since both of Grand's came from outside it [8]. As quoted, though, the sentence covers Trezor devices without qualification. The available material does not include Trezor's response to Grand's notification.
The Ledger cases set the sequence. According to zetter-zeroday.com, Grand initially found implants in four Ledger devices sold by unauthorized merchants that looked like fly-by-night sellers [12]. Implants later appeared in devices from authorized Ledger resellers and were used to steal $100 million in crypto [11]. The Trezor cases match the first stage.
Trezor announced its seller cut on X out of an "abundance of caution," and Sanders called it a "preventive step" to have better control over its supply chain [14][16]. The zetter-zeroday.com author offers another explanation. The Trezor findings might be a precursor to implants in units from authorized resellers, the author wrote, and the cut suggests Trezor shares that worry [18].
Add Grand's two cases to the earlier Kaspersky find and Trezor tampering now spans three sales venues over roughly three years: a Russian marketplace, Facebook Marketplace and a TikTok shop [13][10].
What to watch
- A swapped-chip Trezor from an authorized seller. That would move Trezor from the first stage of Ledger's sequence to the second.
- Whether Trezor names the sellers it dropped and says what it did after Grand's August notification.
- Any link between Grand's two units, the earlier Kaspersky case and a single group.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence50
- Adoption
- Insufficient
- Hype gap−10
- Incentives55
- Confidence50
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
Joe Grand found implants in two Trezor wallets and notified Trezor about them in August.
- [2]
Grand found an implant in a Trezor Model T that someone bought via Facebook Marketplace in Canada some time in 2025, and in a Trezor One that someone obtained from a TikTok shop in August.
- [3]
The buyer of the Trezor One became suspicious when about $50 got transferred out of his crypto account.
- [4]
The Trezor One and Model T are discontinued, but Trezor will keep distributing software updates until 2031 and security updates until 2036, and customers still buy them from third-party sellers.
- [5]
In both wallets the attackers replaced the microcontroller so that, instead of generating random recovery seed phrases, it generated one of a dozen or so pre-determined seed phrases coded into it, allowing the attackers to guess the recovery seeds for the accounts.
- [6]
Grand says the legitimate microcontrollers in Trezor devices have code-protection features meant to prevent someone from accessing and changing the code.
- [7]
Because Trezor's code is open source, it was easy for the attackers to obtain it, modify it and program it into a new, unsecured device by replacing the legitimate chip with their own.
- [8]
The Trezor One and Model T implants Grand found were sold by third-party nonauthorized sellers, not by authorized sellers.
- [9]
Ledger and Trezor have both warned customers for years to buy directly from their own web sites or from authorized merchants.
- [10]
Three years ago, Kaspersky Lab found an implant in a Trezor wallet sold on a popular Russian marketplace; Kaspersky called it a fake wallet, but it was a real Trezor wallet that had been compromised.
- [11]
The Ledger implants became news because they were sold in devices distributed by authorized Ledger resellers and were subsequently used to steal $100 million in crypto from owners of compromised devices.
- [12]
Grand initially found implants in four Ledger devices sold online by unauthorized Ledger merchants that appeared to be fly-by-night sellers who popped up in online marketplaces and disappeared after days or weeks.
- [13]
Trezor implant cases now span three sales venues over roughly three years: a Russian marketplace, Facebook Marketplace and a TikTok shop.
- [14]
Trezor announced on X that it would reduce the number of merchants authorized to sell its devices, out of an "abundance of caution."
- [15]
Trezor Chief Commercial Officer Danny Sanders wrote that there was "not a single piece of evidence that Trezor devices have been compromised."
- [16]
Sanders described the reduction in authorized sellers as a "preventive step" to have better control over Trezor's supply chain.
- [17]
The zetter-zeroday.com author wrote of Sanders's statement: "But this isn't exactly true."
- [18]
The zetter-zeroday.com author wrote that the Trezor discoveries might be a precursor to implants showing up in Trezor devices sold by authorized resellers, and that Trezor's de-authorizing of some resellers shows it may be worried the problem could spread to authorized sellers.
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Sources
1 independent publisher whose own reporting we read for this story.
- Trezor Wallets Also Compromised with Implants
zetter-zeroday.com
1 article · October 13, 2026
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Topics
- Cryptocurrency theftFollow
- Hardware Wallet SecurityFollow
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