Money from Harmony’s Horizon Bridge has started to move to the Tornado Cash Ethereum mixer, indicating that the attacker has no intention of accepting the $1 million reward offered.
The decision to blackout the illicit gains answers questions about whether Team Harmony’s offer of just 1% of the $100 million in stolen cryptocurrency on Friday would be enough to convince a scalper to return it.
A total of 18,036.3 Ether (ETH), worth about $21 million, was moved from the main wallet of the Horizon Bridge scalper at 03:10AM ET on Tuesday. This money was then divided in three ways equally and sent to three different addresses in individual transactions, respectively, over the next ten hours.
Tornado Cash supports mixing up to 100 ETH at a time, which means that mixing large amounts can easily take several hours. Mixing ETH is a privacy measure designed to obfuscate the currency transaction path so that it cannot be traced back to previous transactions.
The first and second wallets that received Ethereum from the scalper’s core wallet have completed shuffling coins and are now leaving around 16.3 Ether collectively, an amount that is likely too small to bother you.
The third wallet has been busy sending batches of 100 ETH to Tornado at eight-minute intervals and still has 2,800 coins left at the time of writing.
Cointelegraph has not received a response from the Harmony team about what it plans to do to replace the stolen funds at the bridge.
The project’s Twitter account confirmed on Monday that the team was working with “two well-known partners in blockchain tracking and analysis,” along with the US Federal Bureau of Investigation, to investigate the hack.
About $80 million of ETH is still in the explorer’s core wallet. They’ll likely return a portion of the stolen funds to Horizon, or perhaps take a breather because the scalper took more than 13 hours to mix in just $21 million.
Although the value of the initial withdrawal was estimated to be around $100 million at the time, positive fluctuations in the price of Ethereum increased the dollar’s value to $101.5 million.
Stephen Tse, founder of Harmony, confirmed Saturday that the exploiter has taken control of the two signers wanted by Horizon Bridge for the multi-signature address used to secure the funds. He noted that the Ethereum side of the bridge affected by the exploit has been moved to a more secure multisig wallet that requires four signers.
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The horizon is the latest in a growing list of iconic bridges that have come under attack. The biggest token bridge that was hacked was the Poly Network in 2021, losing $610 million that was almost entirely returned.
In total, more than $1 billion has been mined from the Mete, Wormhole, Ronin and now Horizon bridges by nefarious means in 2022 so far.