Over $600 million has been stolen from DeFi platform Poly Network in one of the biggest crypto heists of all time - but the hacker has returned some of the cash already

• Cryptocurrency worth over $600 million was stolen from DeFi platform Poly Network on Tuesday.
• The hacker appears to be returning some of their loot to Poly Network.
• This is the latest in a series of DeFi crypto hacks, which have skyrocketed this year.

Cryptocurrency worth over $600 million were stolen from decentralized finance platform Poly Network, in one of the biggest crypto heists ever on Tuesday, with developers putting out a plea on Twitter to the hacker asking for the money back - which the thieves have appeared to respond to.

Poly Network announced the hack on Twitter, noting the attack took place on across the binance, polygon and ethereum blockchains and involved various tokens, including shiba inu, wrapped ether, wrapped bitcoin, uniswap and a series of stablecoins. The platform also published the hacker's wallet addresses and urged crypto exchanges and miners to halt tokens from these addresses.

In response, around $33 million of stablecoin Tether that were part of the hack were frozen by its issuer, Paolo Ardoino, its chief technology officer said on Twitter.

They also said they had found the vulnerability on the platform that the hacker used to seize the coins.

Poly Network last said it had started receiving money back from the hacker, sharing on Twitter that polygon tokens worth over $1 million had been returned.

Coindesk had reported on Wednesday that the hacker said they would return the funds in a message embedded on an ethereum blockchain-based transaction.

"Failed to contact the poly. I need a secured multisig wallet from you," the hacker added in a separate transaction.

Poly Network then created the requested multi-signature wallets and reached out to the hacker via Twitter.

"Law enforcement in any country will regard this as a major economic crime and you will be pursued. It is very unwise for you to do any further transactions. The money you stole are from tens of thousands of crypto community members, hence the people. You should talk to us to work out a solution," the network's developers wrote on Twitter.

This is the latest in a growing number of crypto hacks - and likely one of the biggest so far, with Poly Network saying it was the largest amount of money seized in the history of DeFi. Cryptocurrency intelligence firm Ciphertrace noted in a recent report that DeFi hacks made up over three quarters of crypto money seizures so far this year - at the end of July, around $361 million had been stolen in DeFi hacks compared to $111 million in other crypto crimes.

Across the whole of 2020, DeFi hacks accounted for just $129 million, or 25%, of the total $516 million seized in crypto crimes according to Ciphertrace's report.