It seems pleading worked. Poly Network, which urged hackers to return more than $610 million in cryptocurrency stolen from its decentralized finance platform this week in one of the largest ever cryptocurrency thefts, says almost all of the assets have been returned. In a Thursday tweet, the platform said the culprit was a "white hat" hacker, meaning an ethical security researcher who helps expose cyber vulnerabilities, per the Guardian. It added the stolen funds were transferred to a digital wallet controlled by it and the hacker. Poly Network said the only coins not recovered, worth $33 million, were frozen by cryptocurrency firm Tether. In digital messages on Wednesday, a person claiming responsibility for the hack said the platform offered $500,000, along with a promise of immunity from prosecution, if the stolen coins were returned.
The apparent hacker, dubbed Mr. White Hat, said the offer—which angered some legal and security experts—was refused, per the BBC. In other messages, the individual wrote of carrying out the attack "for fun" and wanting to "expose the vulnerability"—Poly Network had pointed to a "vulnerability between contract calls"—before others could exploit it. They added the plan was "always" to return the tokens. But that claim has been met with skepticism. "I wonder whether this hacker stole the funds, realized how much publicity and attention they were getting, realized wherever they moved the funds they would be watched, and decided to give it back," Tom Robinson, co-founder of crypto tracking firm Elliptic, tells the BBC. Blockchain security firm SlowMist had said it was close to identifying the attacker, who claimed to be "untraceable," per CNBC. (Read more hackers stories.)