Mercado Bitcoin pauses transfers after security incident drains tens of millions

Mercado Bitcoin, described by the Block and Decrypt as the largest cryptocurrency exchange in Brazil, suspended deposits and withdrawals on Nov. 2 after confirming a security incident. Security analysts and news outlets estimated the breach drained between $40 million and $46 million from the platform. Decrypt and AMBCrypto reported the losses at $40 million, while Cointelegraph, Protos, and the Block put the estimated loss at $46 million. [1][2][4][7][8][9]

Despite the exchange announcing a pause on operations, addresses linked to the breach remained active. Cointelegraph reported that wallets associated with the incident continued to receive transferred funds for hours after transactions were officially paused. Dickson Wu, a senior security engineer at Certik, stated in an initial post-mortem that the attackers targeted eight small chains over a four-hour period. [1][4]

Mercado Bitcoin stated that its customers suffered no losses of funds or personal data, according to CryptoSlate and Cointelegraph. CryptoSlate further reported that stablecoin issuer Tether froze more than 4.5 million USDT linked to the security breach on Nov. 2. Tether Chief Executive Paolo Ardoino confirmed the asset freeze, which follows a $20 million strategic investment that Tether made in Mercado Bitcoin in July to support its expansion into tokenization and payments. [1][4]

Tether is a dollar-pegged stablecoin that operates under the currency code USDT, issued by Tether Limited since 2014. Mercado Bitcoin has released tracking addresses associated with the stolen assets and stated that restoration work is continuing, though the exchange has not provided a timeline for reopening. [1][12]