CoinDesk
Mercado Bitcoin customer deposit addresses kept getting drained for roughly four hours after the exchange said it had contained the attack, according to blockchain data platform Bitquery. The attacker emptied 36,042 Ethereum addresses between 12:27 and 16:56 UTC on Nov. 2, even though Mercado Bitcoin said at 12:56 UTC that the breach was contained.
Why it matters
Bitquery traced $48.6 million in stolen assets across 10 blockchains, above the $40 million first reported. The continued withdrawals after the containment announcement raise questions about how quickly the exchange stopped the attacker and suggest access to systems managing customer deposits.
The investigation also identified roughly $391,000 in losses from wallets Bitquery ties mostly to BitMart. The same attacker-controlled address received funds from wallets on Base, Arbitrum and Optimism before the Mercado Bitcoin breach. BitMart founder Sheldon Xia confirmed a Nov. 2 hack and said the exchange’s preliminary investigation points to the group behind the Mercado Bitcoin attack. BitMart has not confirmed Bitquery’s loss estimate, and the cause of either breach remains unknown.
Market impact
Mercado Bitcoin pledged to cover all user losses. Tether, Circle and Chainalysis helped freeze more than $15 million in assets. The exchange suspended deposits and withdrawals after the attack and planned to reopen its website in view-only mode on Nov. 9, with no date set for restoring transactions.
The potential overlap between attacks on two exchanges makes the scope of the incident a key security concern. The available findings point to a possible shared attacker, but do not establish that the exchanges’ infrastructure was connected.
Frequently asked questions
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How long did the Mercado Bitcoin theft continue after the containment statement?
Bitquery found that customer deposit addresses continued to be drained for roughly four hours after Mercado Bitcoin said the breach was contained.
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How much did Bitquery trace across blockchains?
Bitquery traced $48.6 million in stolen assets across 10 blockchains, above the $40 million first reported.
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What is the reported connection between the Mercado Bitcoin and BitMart hacks?
Bitquery linked about $391,000 in losses, mostly from wallets it ties to BitMart, to the same attacker-controlled address. BitMart founder Sheldon Xia said the exchange’s preliminary investigation points to the group behind the Mercado Bitcoin attack.
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How much did partners help freeze after the Mercado Bitcoin attack?
Tether, Circle and Chainalysis helped freeze more than $15 million in assets.
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What happened to Mercado Bitcoin deposits and withdrawals after the breach?
Mercado Bitcoin suspended deposits and withdrawals and planned to reopen its website in view-only mode on Nov. 9. It had not set a date for restoring transactions.
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