Coldcard Hackers Drain Over $86M from 4,500 Bitcoin Wallets

Hackers have exploited a software flaw in Coldcard, a popular hardware Bitcoin wallet designed for offline 'cold storage', to steal over $86 million from more than 4,500 wallets.

The attack began after Coinkite Inc., the Canada-based company behind Coldcard wallets, warned users about a security flaw last week. By Monday, hackers had stolen about 1,367 Bitcoin worth nearly $86 million, according to Galaxy Research.

Coldcard devices are hardware wallets that store Bitcoin in cold storage, which is considered one of the safest ways to protect cryptocurrency because they remain disconnected from the internet.

However, a flaw in the software used to generate the wallet's 'seed phrase' made it possible for attackers to recreate users' private keys and gain access to their Bitcoin. The issue was linked to how Coinkite implemented its random-number generator while creating seed phrases.