The FBI has accused North Korean-linked hackers of conducting one of the largest known thefts of cryptocurrency — worth some $1.5 billion — from a Dubai-based firm.

North Korean hackers were behind the theft of $1.5 billion of virtual assets last week from Dubai-based cryptocurrency exchange Bybit, the U.S. Federal Bureau of Investigation said, marking the biggest heist in history.

It's only February but hackers have already stolen $1.6 billion in exploits, blockchain security firm Immunefi has said.