Researchers have uncovered evidence that over $1 million worth of Bitcoin (BTC) from addresses linked to Ryuk ransomware attacks was moved through a wallet on Binance.

According to a report by Forbes on Aug. 23 the researchers took a sample of 63 transactions, representing $5.7 million of the over $61 million estimated by the FBI to have been stolen using the Ryuk ransomware.

Of the $5.7 million, $1,064,865 worth of Bitcoin from multiple wallet addresses was bounced through numerous non-connected wallets before eventually finding its way to Binance, where it was cashed out.

The Binance wallet has been in use as recently as this month, although the latest transaction, occurring on Aug 22, just a day before the Forbes article was published, emptied the wallet completely.

The remaining $4.7 million of Bitcoin being traced by the researchers is currently still being held in a number of off-exchange addresses.

Cointelegraph spoke to the Binance Security Team about the incident, which explained that the transactions outlined in the Forbes article occurred over 18 months ago, and the relevant accounts had been tracked and reviewed at the time.

Furthermore, the fungible nature of most cryptocurrency makes it impossible to know whether a particular token has come from a fraudulent or legitimate source, once the two have been combined:

“This is further complicated by the fact that Binance has a wide variety of customers operating on its platform, with some customers receiving such funds through simple peer-to-peer trades, and others receiving through corporate services which leverage our platform for liquidity.”

Binance has a number of security systems in place, using various techniques to identify potentially malicious activities. “The system is under constant improvement to ensure the utmost vigilance for such activities, while minimizing the risk of false-positives.”

As Cointelegraph reported, Binance recently collaborated with law enforcement in Ukraine to help capture a gang of cybercriminals trying to launder $42 million through the exchange.