Decentralised financed (DeFi) platform Poly Network was hacked and had US$600 million of cryptocurrencies stolen this week - and has written an open letter to the hacker asking for it back.
The company, a Chinese software business, allows swapping and processing of cryptocurrency transactions across different blockchain platforms.
In the cyber attack Polygon, Ethereum and Binance were the platforms targeted, the company said.
"After preliminary investigation, we located the cause of the vulnerability. The hacker exploited a vulnerability between contract calls, the exploit was not caused by the single keeper as rumoured," Poly Network wrote in another tweet.
The company has said it will take legal action and has called on exchanges to blacklist the tokens coming from the addresses of the stolen cryptocurrency. But it also tried a more direct appeal with the open letter.
"Dear Hacker, we are the Poly Network team. We want to establish communication with you and urge you to return the hacked assets," it wrote.
"The amount of money you hacked is the biggest one in the defi history. 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.
"You should talk to us to work out a solution," it concluded.
Paolo Ardoino, the chief technology officer of blockchain platform Tether, said he had frozen US$33 million worth of digital assets since the hack.
And O3Labs, a customer of Poly Network, has suspended trading between blockchain platforms due to the hack.
"We are in contact with the team. Please be patient to back (sic) to full functionality. The non-cross-chain function is available and can be used normally," it wrote.
But not everyone is trying to hold the hacker to account, website Decrypt reported.
An online user tipped off the hacker, telling them to avoid using the blacklisted Tether-based tokens, earning themselves a tip of 13.37 Ethereum cryptocurrency.
At current rates that's worth around NZ$60,000.
Cryptocurrencies are virtual currencies with high profile supporters like Tesla-founder Elon Musk, who has been criticised for his tweets that have caused price spikes.
Earlier this week Twitter-founder Jack Dorsey tweeted that bitcoin - the most popular cryptocurrency - would unite the United States and, eventually, the world.
The New Zealand Government has launched an inquiry into virtual money which will look at the nature, impact and risk of cryptocurrencies.
The latest virtual heist will give that inquiry more to ponder.