Seed Generation

A new wave of bitcoin sweeps tied to Coldcard-generated addresses may have lifted observed losses to about 1,816 BTC, or nearly $114 million, since July 30. Researchers say the latest pending transactions appear to use replace-by-fee, giving alert users a narrow window to outbid the attacker before confirmation.

A Coldcard firmware vulnerability tied to weak software-based randomness has been linked to three waves of bitcoin sweeps across thousands of addresses. The latest activity is targeting smaller balances and using more complex onchain collection patterns.

A flaw in Coldcard firmware key generation enabled an attacker to drain roughly 594 bitcoin, worth about $38 million, from around 500 single-signature wallets. Coinkite has warned users who created seeds on certain Mk3 devices, while early analysis suggests Mk4, Q and Mk5 devices are not affected so far.