Why are North Korean hackers such good crypto-thieves?

FEBRUARY 21st began as a typical day, recalled Ben Zhou, the boss of ByBit, a Dubai-based cryptocurrency exchange. Before going to bed, he approved a fund transfer between the firm’s accounts, a “typical manoeuvre” performed while servicing more than 60m users around the world. Half an hour later he got a phone call. “Ben, there’s an issue,” his chief financial officer said, voice shaking. “We might be hacked…all of the Ethereum is gone.”