TL;DR
Brazil-based Mercado Bitcoin suspended deposits and withdrawals after suspicious transfers affected wallets across at least 10 blockchain networks.
Security researchers estimate that more than $40 million in crypto assets moved to new addresses.
The exchange says it contained the incident, with no customer harm or data breach reported.
Tether froze $4.5 million in USDT linked to the incident, while the attacker’s identity and access method remain unknown.
Mercado Bitcoin Halts Transactions Following Security Incident
Brazilian cryptocurrency exchange Mercado Bitcoin has suspended deposits and withdrawals after unusual activity drained wallets associated with the platform across multiple blockchain networks.
Security researchers estimate that more than $40 million in digital assets moved during the incident. The activity was reported across networks including Ethereum, Solana, Tron, Polygon, Arbitrum, Avalanche, BNB Chain and Stellar.
According to information shared by crypto security researchers, the largest wave of transfers occurred within approximately 34 minutes, between 06:19 and 06:53 UTC on Monday.
The reported holdings transferred to new addresses include roughly 2,852 ETH, 106 BTC, 10,700 SOL, 6.7 million XLM and 77,000 AVAX, alongside more than 200 other tokens.
However, Mercado Bitcoin has not independently confirmed the estimated $40 million loss.
Exchange Says Incident Is Contained
In a statement on X, Mercado Bitcoin said it had identified and swiftly contained a security incident. The company added that customers had not been harmed and that no data breach had occurred.
Deposits and withdrawals remain suspended as a precaution while the exchange investigates the activity, traces the assets and coordinates with authorities.
The platform has also published destination wallet addresses across several networks to help security teams and other industry participants monitor the transferred funds.
Investigators have yet to establish how the attacker obtained the ability to authorize the transactions. The reported transfers were ordinary blockchain transactions rather than the result of a confirmed smart contract exploit.
Tether Freezes $4.5 Million in USDT
Tether founder Paolo Ardoino confirmed that approximately $4.5 million in USDT linked to the incident had been frozen. The action provides a potential recovery avenue for part of the reported funds, although the broader status of the transferred assets remains unclear.
The incident comes days after Binance suffered a separate $6.3 billion security breach attributed by the FBI to North Korea’s TraderTraitor hacking group.
Despite the timing, there is currently no public evidence connecting the Mercado Bitcoin incident to the Binance attack.
For now, the investigation’s main questions concern the total amount affected, how access was obtained and when normal exchange services can resume. The answers could have broader implications for how cryptocurrency platforms secure wallets and manage assets across multiple blockchain networks.
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