Mercado Bitcoin (MB), Brazil’s largest crypto exchange, has been hacked, according to multiple blockchain reports. The exchange itself confirmed the incident and has temporarily suspended deposits and withdrawals.
Blockchain security firm Hypernative estimates $40 million in losses from the exchange’s wallets. This comes just days after the record $6 billion Binance hack.
Here is the statement in full (translated from Portuguese):
We identified and quickly contained a security incident in one of our systems overnight.
We stress that:
• There was no loss to clients;
• There was no data leak.As a preventive protection measure, deposits and withdrawals are temporarily suspended. Our teams are mobilized investigating the case, tracing the assets and coordinating measures with the competent authorities.
We will keep providing regular updates here.
The statement gives no timeline for reopening deposits and withdrawals.
What Hypernative flagged
According to Hypernative, the possible attack involved wallets spread across at least 10 blockchains, including Bitcoin, Ethereum, Solana, Tron, Polygon, Arbitrum, Avalanche, BNB Smart Chain, and Stellar.
The first suspicious movements appeared around 11 PM Sunday night in Brazil.
Wallets attributed to MB sent most of their funds to newly created addresses linked to the possible attacker.
MB’s statement refers to an incident “overnight,” the same period as those transfers, but it does not directly connect the two.
Rather than exploiting flaws in smart contracts, the movements were ordinary cryptocurrency transfers, signed as if authorized by the source wallets themselves.
Hypernative says it is still unclear how the attacker obtained that signing capability. Open questions include possible exposure of private keys and failures in the infrastructure that authorizes transfers.
What is still unknown
Answers are still missing on the origin of the incident, the real amount lost, whether the moved assets belonged to clients or to the exchange itself, and when deposits and withdrawals will return to normal.
MB says it is investigating, tracing the assets and working with authorities, and promises regular updates.
This is a developing story.
