$611 million in bitcoin was stolen from PolyNetwork, a system that allows users to conduct business across blockchains, in what is being labelled the worst theft in the history of digital currencies.
Unlike online transactions that now employ national currencies, blockchains are decentralised ledgers that allow users to conduct transactions without requiring approval from a central authority.
PolyNetwork stated that the hack affected “tens of thousands” of users in a message posted on Twitter. Tether, a stablecoin, was also involved in the crime and has frozen $33 million, rendering it inaccessible to the hackers.
In a strange turn of events Wednesday, the hackers began returning some of the funds they stole.
They sent a message to Poly Network embedded in a cryptocurrency transaction saying they were “ready to return” the funds. The DeFi platform responded requesting the money be sent to three crypto addresses.
DeFi has become a key target for attacks.
Since the start of the year until July, DeFi-related hacks totaled $361 million — an increase of nearly three times from all of 2020, according to cryptocurrency compliance company CipherTrace.
DeFi-related fraud is also on the rise. In the first seven months of the year, it accounted for 54% of total crypto fraud volume versus 3% for all of last year.