Heco Bridge exploiters launder over $145 million in ether via Tornado Cash

Hackers who exploited the Heco Bridge last year have laundered more than 40,000 ether — worth $145.7 million — via Tornado Cash over the past eight days, according to on-chain data.

The Heco Bridge is used for moving funds between Ethereum ETH -3.03% and the Heco Chain — a blockchain set up by the HTX exchange (formerly Huobi). Tornado Cash is a cryptocurrency mixer that provides privacy by obfuscating the origins and destinations of Ethereum transactions.

“As of today (22 Mar. 2024, UTC), HECO bridge exploiters have transferred ~$40,391.8 ETH (equivalent to ~$145.7 million) to Tornado Cash within the last 8 days,” the blockchain security and data analytics firm PeckShield posted on X.

HTX also impacted

The November 2023 Heco Bridge hack resulted in a loss of around $111 million on the day of the exploit, according to PeckShield. The funds — including ether, USDT, USDC and HBTC — were immediately sent to decentralized exchanges and sold for other tokens, The Block previously reported .

Wintermute Head of Research Igor Igamberdiev suggested that there was an additional exploit of HTX at the time, citing suspicious transfers of $23.4 million. He said these transactions shared the same patterns as those in the Heco Bridge exploit and occurred shortly afterward. HTX also started moving funds from a different hot wallet to what's labeled a recovery wallet and temporarily disabled deposits and withdrawals.

“HTX and Heco cross-chain bridge undergo hacker attack. HTX will fully compensate for HTX's hot wallet losses. Deposits and withdrawals temporarily suspended. All funds in HTX are secure, and the community can rest assured. We are investigating the specific reasons for the hacker attack,” HTX advisor Justin Sun said at the time, confirming the analysis. It followed a 5,000 ETH hack on HTX in September 2023. 

Earlier this week, Tornado Cash developer Alexey Pertsev was accused of laundering $1.2 billion of illegal funds through the platform, according to an indictment in the Netherlands. Pertsev is currently awaiting trial in the country on March 26 for charges related to money laundering and other financial crimes.

The Block reached out to HTX, Heco Chain and Justin Sun for comment.

Disclaimer: Evgeny Gaevoy, the founder and CEO of Wintermute, previously sat on The Block's board of directors from April 2023 to early November 2023 and remains a minority shareholder.