Hackers Stole $38 Million in Bitcoin in 25 Minutes, And It’s Getting Worse...
Mark Moss examines a reported Coldcard hardware-wallet exploit, the theft of roughly $130 million in Bitcoin, and the movement of about 189,000 previously inactive Bitcoin. He concludes that the Bitcoin network itself did not fail; instead, the incident exposed weaknesses in key generation and showed that changing devices without creating new seeds may leave users vulnerable, while diversified custody can make a single failure survivable.
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Mark Moss says Coinkite warned that certain Coldcard firmware versions could generate weak seed phrases, creating a vulnerability in the key-generation process.
Moss says the exploit reportedly resulted in about $130 million worth of Bitcoin being stolen, although the exact amount remains uncertain.
He emphasizes that the incident did not compromise Bitcoin's blockchain or signature rules; it affected how some Coldcard keys were generated.
Moss reports that roughly 189,000 inactive Bitcoin moved during a single week around the custody crisis, with much of it appearing to head toward exchanges, though the ownership and intent cannot be confirmed.
He cautions that moving funds from a potentially compromised Coldcard to another device while reusing the original seed does not remove the vulnerability, because the old keys are recreated.
Moss says genuine migration requires an independently generated seed, new keys, a verified address, and an on-chain transfer from the old wallet.
Coldcard Exploit Explained
Mark Moss explains that the reported Coldcard incident involved weak seed generation, not a failure of Bitcoin's network or signature verification.
Moss's Custody Losses
Moss recounts losing 17.8 Bitcoin from a hot wallet and more than 27 Bitcoin from an exchange, illustrating the different risks of self-custody and intermediaries.
Single-Device Dependency
Revisiting a 2021 warning, Moss argues that the solution is not finding a perfect hardware wallet but designing custody so one compromised device cannot cause total loss.
Multisignature Risk Diversification
Moss describes using independently generated keys from different manufacturers and locations in a two-of-three multisignature arrangement.
Custody Tradeoffs
Moss compares hot wallets, exchanges, single-signature hardware wallets, multisignature custody, and brokerage exposure as choices involving different risks and complexities.
The Single-Failure Test
Moss gives a five-question review covering control, total-loss scenarios, independent key creation, recovery by successors, and whether security matches the consequences.
Survivable Bitcoin Security
Moss concludes that moving Bitcoin does not necessarily remove risk and that custody should be diversified so no single dependency can destroy everything.
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