Coldcard issues Mk3 warning as experts examine $38M Bitcoin wallet drain

Canadian Bitcoin hardware maker Coinkite has warned users of its Coldcard Mk3 signing device to move funds from wallets whose seed phrases were generated on affected firmware. On Thursday, Coinkite said seeds created on an Mk3 running firmware version 4.0.1, released in March 2021, or any later Mk3 version may put funds at risk. The issue extends through version 5.0.3, the final firmware supporting the Mk3, while the Mk4, Q and Mk5 are not affected, according to the company’s early analysis.The warning comes as Bitcoin security specialists examine an unexplained, coordinated sweep involving 594.48 BTC from single-signature addresses. However, no definitive public evidence has established that the Mk3 issue caused those transfers.“Out of an abundance of caution,” Coinkite urged affected users to generate a new seed on an unaffected device, verify its backup and receive address, send a small test transaction and only then move the remaining funds. The company said its investigation is ongoing and promised a formal technical review.Coinkite said its early analysis indicates that affected seeds used with a BIP-39 passphrase face minimal risk, stressing that this refers to a passphrase ...