Mercado Bitcoin Hacker Moves $8 Million in Ethereum; Tether Freezes More Than $9 Million
Key Facts
The hacker who targeted Mercado Bitcoin transferred $8 million worth of Ethereum to new wallets on November 3, according to an Arkham post cited by Crypto.news, following a breach at the Brazilian exchange the previous day. Arkham said the attacker held about $46 million in cryptocurrencies when the estimate was published. The company raised the possibility that the attacker might later deposit the Ethereum into Tornado Cash, but did not confirm that this had happened. In a parallel response, Chainalysis said it helped coordinate Tether’s freezing of more than $9 million in stolen funds. These developments put the attacker’s ongoing transfers alongside efforts to disrupt some of the funds that could be frozen.
The attack began in the early hours of November 2, according to Chainalysis, which estimated that about $49 million in assets had been stolen across 17 blockchains. Bitquery separately estimated that $48.5 million left the exchange’s hot wallets across 10 chains that day. Arkham said its initial estimate of the stolen assets was at least $46 million, then said in its November 3 post that the attacker’s wallet held about $46 million. These figures differ among the firms tracking the movements, while they agree that the attack involved assets across multiple networks. In an earlier account on the day of the attack, Bitquery said $19.5 million had moved to 10 new Ethereum wallets by 15:46 UTC, and that only one wallet later sent $18.
Mercado Bitcoin said it discovered and quickly contained a security incident in one of its systems on the morning of November 2. The exchange temporarily halted deposits and withdrawals while it investigated the incident, tracked the assets and coordinated with authorities. The company said customers were not affected and their data had not been compromised. In an announcement cited by CoinDesk on November 3, the exchange said it would cover customer losses, estimating the missing funds at about $38 million. It added that $11 million had been frozen with help from Tether, Circle and Chainalysis, a total estimate the exchange gave for the companies’ response.
Chainalysis said its team contacted law enforcement within 30 minutes of the response beginning and provided addresses whose assets could be frozen. By the morning of November 2, the company had helped freeze $4 million in stolen stablecoins. It then said coordination enabled Tether to take action and freeze more than $9 million in stolen funds. Chainalysis explained that centrally issued stablecoins may be frozen before they are converted into assets such as BTC and ETH, which are harder to disrupt. It said it was continuing to track the remaining funds, while the possibility of Tornado Cash use raised by Arkham remained unconfirmed.
In market moves recorded during the session, ETH/USD closed at $2,253.29 on November 2, then at $2,259.41 on November 3, according to EL7 data. The Mercado Bitcoin incident came amid a series of hacks in the cryptocurrency sector in late October, according to The Block, which cited the estimated $6 billion Binance theft. The cited sources did not give a specific date for the resumption of deposits and withdrawals at Mercado Bitcoin. The exchange said it had temporarily suspended them to investigate, track assets and coordinate with authorities, while Chainalysis said it was continuing to track funds that had not been frozen.