Brazil’s premier cryptocurrency exchange kept both deposits and withdrawals halted on Monday following a security breach affecting one of its infrastructure systems. This temporary shutdown prevented users from transferring capital into or out of the trading platform while technicians worked to bring normal services back online.
Mercado Bitcoin announced via an official statement on X that it successfully isolated and contained the security event. The platform assured clients that user funds experienced no deficits and that no information leakage occurred, framing the suspension purely as a precautionary measure. Their personnel are currently conducting investigations, tracking digital assets, and cooperating closely with law enforcement, according to the firm. Citing Bloomberg, the enterprise stated that it intends to cover the entire deficit itself.
Management has not yet disclosed which exact system suffered the compromise, the precise volume of funds removed, or a specific timeline for resuming full functionality. Initial announcements contained no definitive aggregate loss amount or schedule for restoration.
Mercado Bitcoin subsequently shared recipient addresses associated with transfers from the breach, spanning Bitcoin, Ethereum-compatible chains, Solana, Stellar, and Tron. The platform explained that publishing these destinations is meant to aid in identification and tracking efforts. Meanwhile, blockchain security agency Hypernative calculated preliminary estimates placing suspicious outflows above $40 million across multiple decentralized networks. The exchange has not formally verified that specific total.
Additional analysts are pointing toward higher numbers while noting that asset draining remains active.
Stablecoin provider Tether has actively joined the mitigation efforts. Tether Chief Executive Officer Paolo Ardoino noted on X at 10:06 a.m. Eastern Time that his firm successfully locked over 4.5 million USDT connected to the attack. Tether previously injected $20 million into Mercado Bitcoin this past July, noting at the time that the exchange served a user base of 4.5 million individuals.
A Challenging Week for Mercado and Alternative Exchanges
This security breach arrives just days after one of the largest cryptocurrency thefts in recent history. On October 29, malicious actors accessed $6.3 billion worth of assets at Binance after compromising an engineer’s laptop, thereby gaining entry to internal systems utilized for managing customer withdrawals.
Binance reported finding zero indications that private cryptographic keys were compromised. By November 1, the exchange had replenished 95 percent of the pilfered reserves and initiated a phased reactivation of withdrawal services.
Regarding official investigations, the Federal Bureau of Investigation pointed to North Korea as the perpetrator behind the assault, while the United States Secret Service collaborates with Circle to trace and freeze assets. Tether disclosed that roughly $1.57 billion of USDT had been blocked, and Circle announced it locked more than $800 million of USDC alongside regulatory partners.
Binance revealed that it uncovered supplementary vector entry points past the initial intrusion, which the exchange initially attributed solely to a worker’s compromised portable computer. The trading platform has yet to release a comprehensive post-mortem detailing how the hackers orchestrated and carried out the operation, which external calculations indicate required at least 36 hours of preliminary preparation.
Furthermore, the ultimate destination of approximately $3.3 billion in unsecured and un-frozen stolen capital remains unexplained, and management has not clarified how much they anticipate recovering from that remaining balance. Investigators continue monitoring digital wallet transactions spread across ten distinct blockchain ledgers.
Originally published at https://bitcoinmagazine.com/news/brazils-mercado-bitcoin-freezes-40-million.
