Coldcard Attack Wave Sweeps 389 Bitcoin Amid Growing Theft Estimate

Coldcard users are being warned of another wave of coordinated thefts targeting their Bitcoin hardware wallets. This latest attack comes just days after the first wave of attacks on Thursday, with Galaxy research head Alex Thorn flagging 218 transactions impacting 462 potential victim addresses in the last few hours. The activity has moved around 388.9 BTC, averaging 13.8 sweeps per block, about 45 times the rate observed before the incident.

Thorn noted that the transactions have a 'fresh destination created for each victim rather than converging on a central collection wallet.' Some funds have already been swept into second hop addresses, he added. Thorn said there are similar transactions in the mempool waiting to be confirmed.

Affected users who control the relevant keys may be able to broadcast a conflicting transaction with a higher fee to move their funds to a secure wallet before the attacker's transaction is confirmed.