Firmware flaw in Coldcard hardware wallets lets attacker drain 1,000+ bitcoin worth $70M from 1,196 cold wallets in 41 minutes on July 30; weak seed generation reduced key possibilities to 4 billion, enabling offline private key reconstruction without touching devices.

How bitcoin cold wallets lost $70 million in an attack that never touched the devices

Galaxy Research said weak seed generation let an attacker recreate likely private keys offline, sweep more than 1,000 BTC from nearly 1,200 wallets and continue searching without ever accessing the devices.Bitcoin cold wallet Coldcard. (Coldcard/Coinkite)More than 1,000 bitcoin, worth about $70 million, were drained from 1,196 Coldcard wallets in a 41-minute span on July 30, nearly double the loss first reported.Researchers say a firmware flaw in certain Coldcard hardware wallets made supposedly...