Cyber hackers have returned nearly half of the $600 million they stole from DeFi platform Poly Network

A man poses with a laptop showing a binary code in front of Server racks in a server center on January 12, 2018, in Berlin, Germany.

Cyber hackers returned nearly half of the $600 million they stole from DeFi platform Poly Network, in what is considered one of the biggest cryptocurrency heists in history.

Around $260 million has been returned as of Wednesday noon, Poly Network said in a tweet.

Of the funds given back, $3.3 million were in ethereum, $256 million in Binance smart chain, and $1 million in polygon, according to the post.

The return of funds follows pleas from Poly Network on Tuesday, asking the hackers for the money back and urging cryptocurrency exchanges and miners to halt tokens from the hacker’s wallets.

“The amount of money you hacked is the biggest in defi history,” Poly Network said in a tweet Tuesday, adding that tens of thousands of people were negatively impacted.

The hackers responded on Wednesday, saying they were “ready to return” the funds they stole. It is unclear when they plan to return the whole sum.

Around $269 million on ethereum and $84 million on polygon remain with the hackers, according to the Poly Network tweet.

The hackers said they stole the funds “for fun :)” because “cross-chain hacking is hot,” according to a Q&A session that was embedded in ethereum transactions sent from the account holding the stolen assets.

The screenshots of the exchange were obtained by Tom Robinson, cofounder of Elliptic, a blockchain analytics and compliance company.

“The Poly network is a decent system,” the hackers said. “It’s one of the most challenging attacks that a hacker can enjoy.”

The hackers said they took the funds after spotting a bug “to keep it safe.”

The cyberattack on Poly Network joins a growing number of attacks on the rapidly growing DeFi space.

Thus far, DeFi hacks made up over three-quarters of cryptocurrency money seizures this year, according to a report by intelligence firm Ciphertrace.

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