Binance temporarily suspended fund transfers and other transactions on Thursday night after it discovered an exploit on its Smart Chain (BSC) blockchain network. Early reports said hackers stole cryptocurrency equivalent to more than $500 million, but Binance chief executive Changpeng Zhao said that the company estimates the breach's impact to be between $100 million and $110 million. A total of $7M had already been frozen.
The cryptocurrency exchange also assured users on Reddit that their funds are safe. As Zhao explained, an exploit on the BSC Token Hub cross-chain bridge, which enables the transfer of cryptocurrency and digital assets like NFTs from one blockchain to another, "resulted in extra BNB" or Binance Coin. That could mean the bad actors minted new BNBs and then moved an equivalent of around $100 million off the blockchain instead of stealing people's actual funds. According to Bleeping Computer, the hacker quickly spread the stolen cryptocurrency in attempts of converting it to other assets, but it's unclear if they had succeeded.
Zhao said the issue has been contained. The Smart Chain network has also started running again - with fixes to stop hackers from getting in - so users might be able to resume their transactions soon. Cross-chain bridge hacks have become a top security risk recently, and this incident is but one of many. Blockchain analyst firm Chainalysis reported back in August that an estimated total of $2 billion in cryptocurrency was stolen across 13 cross-chain bridge hacks. Approximately 69 percent of that amount had been stolen this year alone.