Hackers breached the Ronin network used for the Axie Infinity blockchain-based game, stealing more than $620 million in ether and $25.5 million in stablecoins.
Sky Mavis, Axie Infinity’s owner, said the breach led to the theft of 173,600 ether and 25.5 million USDC from the bridge used for the NFT-based game in a blog post.
The attack, which happened March 23, was discovered Tuesday morning, the company said. Sky Mavis said it was working with “various government agencies to ensure the criminals get brought to justice.”
Axie Infinity is one of the more notable play-to-earn games based on blockchain technology. Its NFTs have recorded more than $4 billion in sales to date. But it's suffered from a big drop in token prices. Sky Mavis has been trying to fix the game by changing its economics, which has led to more player complaints.
Sky Mavis said the companies' in-game tokens, SLP and AXS, were not affected by the hack. It attributed the hack to a vulnerability that resulted from the Axie DAO, the decentralized organization that ostensibly oversees the cryptocurrencies used in Axie Infinity, granting Sky Mavis the ability to sign transactions on its behalf last year in order to deal with a heavy transaction load. Those permissions weren't revoked, and the hackers gained access to Sky Mavis systems and thus the ability to validate blockchain transactions.
"Sky Mavis is committed to ensuring that all of the drained funds are recovered or reimbursed," the company wrote in its blog post. It is not clear if the company has the resources to reimburse victims on its own. It raised $152 million at a nearly $3 billion valuation from Andreessen Horowitz and other investors last year.