“Every step of that runs on the attacker’s machine. The victim’s device is not involved at any point.”
A build setting told Coldcard’s firmware to skip the hardware random number generator and fall back to the chip serial number and a clock register. That cut the key space from astronomical to about four billion, which is a weekend of compute. 1,196 wallets and 1,082 BTC gone in 41 minutes, and Galaxy now puts the total at $75 million across two waves. The part that should end the company: there is no test an owner can run to find out if their seed is one of the bad ones.