The final chunk of $610m (£444.7m) stolen from a cryptocurrency network earlier this month has now been returned, in what has been described as the biggest ever cryptocurrency heist.
The hacker had begun returning the money to the Poly Network following the attack, when $200m of the amount was trapped in a password protected account.
As the hacker returned the first chunk of the money, they appealed for donations for their efforts which exposed the security flaw.
The hacker, dubbed 'Mr. White Hat' by the Poly Network, released the rest of the funds after the platform said it would give the unidentified person a $500,000 bounty for helping eke out the security flaw.
Poly Network also said it offered Mr. White Hat the role of "chief security advisor."
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The hacker later returned the half a million bounty and the donations.
“While it is a rather bizarre turn of events, the returning of the stolen funds could point to the fact that laundering many cryptocurrencies and the process of cashing out can prove difficult," said Jake Moore, cybersecurity specialist at ESET.
About $267m of ethereum (ETH-USD), $252m of Binance coin (BNB-USD) and roughly $85m in USDC tokens were taken, according to wallet addresses posted on Twitter. The looter apparently exploited a vulnerability in Poly Network's systems to make off with the funds.
A note embedded in the return transaction said: "SORRY FOR THE INCONVENIENCE! IT MUST BE ONE OF THE MOST WILD ADVENTURES IN OUR LIVES."
The Poly Network said it is in the process of returning full asset control to users.
"Tether is confirming the final unfreezing process with us," the company said on twitter on 23 August.
"This attack is likely to have been watched closely by cybercriminals and law enforcement alike, potentially opening up the possibility of copycat attacks like this occurring again. However, next time, the attackers may plan a stealthier exit strategy involving cryptocurrencies that aren’t so well monitored," said Moore.
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