Mercado Bitcoin, Brazil's largest cryptocurrency exchange, confirmed Monday that it suffered a security incident involving approximately $46.3 million in assets, according to Arkham data cited by The Block. 'We identified and swiftly contained a security incident in one of our systems early this morning,' the exchange said in a post on X.

Source: The Block

The exchange temporarily suspended deposits and withdrawals as a precaution while its teams investigate the incident, track the assets and coordinate with authorities, The Block reported. It said the incident did not affect customers and did not result in a data breach, and it published the destination wallet addresses associated with the transactions to help blockchain security firms and other parties monitor and track the assets.

Source: The Block

$46.3 millionEstimated assets taken — yaani 4.63 crore dollars — according to Arkham data
4.5 million USDTFrozen by Tether, its CEO Paolo Ardoino confirmed — yaani 45 lakh USDT
$6.2 millionFrozen by Tether and Circle by 16:42 UTC, Cointelegraph said — yaani 62 lakh dollars
4.5 millionMercado Bitcoin users as of July, Cointelegraph reported

Tether CEO Paolo Ardoino confirmed that the stablecoin issuer had frozen more than 4.5 million USDT linked to the incident, The Block said. Arkham analyst Emmett Gallic said the attacker was sweeping funds from older deposit addresses and selling memecoins and other altcoins.

Source: The Block

Cointelegraph, in an update published on Monday, said that despite the suspension, addresses associated with the incident continued to receive funds for hours afterward. Senior security engineer at CertiK, Dickson Wu, published an initial post-mortem saying the attackers 'picked at eight small chains for four hours,' including Base, Optimism and Arbitrum, before the attack moved to the company's main hot wallets and transferred tiny amounts of Ether from 27,160 different addresses. 'So whoever did this can also move money out of MB's customer deposit addresses,' Wu wrote. Security firms said the hack was carried out through standard transfers rather than a smart contract exploit, Cointelegraph reported.

Source: Cointelegraph

By 16:42 UTC, approximately $6.2 million of the stolen funds had been frozen by stablecoin issuers Tether and Circle, about $20 million had been transferred into newly created wallets, and over $20 million remained in associated addresses identified by Mercado Bitcoin, including all 106 BTC, Cointelegraph reported. A spokesperson told Cointelegraph customers had suffered no losses and no data had been leaked, but the company did not respond to requests for comment on the continued transfers. The hack has not yet been attributed to an organised group and remains under investigation.

Source: Cointelegraph

This is a separate incident from last week's Binance theft: Awaaz Punjab reported on October 29-31 that about $6.3 billion was taken from Binance, the world's largest crypto exchange, in an attack the FBI later attributed to North Korea's TraderTraitor group. Read the earlier report: $6.3 billion Binance hack

Mercado Bitcoin had 4.5 million users as of July, when Tether announced a $20 million investment to support its expansion in tokenisation, payments and credit, Cointelegraph said. The Block noted the incident comes amid a string of security breaches across the crypto industry in recent days, following Thursday's Binance hack, a $2.65 million exploit at Polymarket the same day, and a Saturday hijacking of a dozen DeFi websites that Blockaid said stole about $138,000.

Source: The Block