Cryptocurrency mining marketplace NiceHash has confirmed that yesterday's hack resulted in the loss of over 4,700 BTC, an amount worth more than $78 million at press-time prices.

In a video update streamed live on Facebook, CEO and co-founder Marko Kobal provided an update to yesterday's dramatic announcement that the company, founded in 2014, had incurred a hack and subsequent theft. The news followed growing reports of emptied wallets, as well as an extended downtime period for the service's website.

According to Kobal, the attack began in the early hours of Dec. 6 after an employee's computer had been compromised. Kobal, who said that the team is working with law enforcement, explained that "we're still conducting forensic analysis" to determine how it happened.

Over the course of several hours, Kobal said, those behind the theft gained access to their systems, and that at 3:34 am CET began to siphon off funds from the company's accounts. As reported yesterday, a wallet address circulated by users showed approximately 4,736.42 BTC being held – an amount worth approximately $78.3 million according to CoinDesk's Bitcoin Price Index (BPI).

As of press time, the funds are still being held in the address in question.

Kobal went on to say he couldn't provide additional details, though he added that the attack appears to be "incredibly coordinated and highly sophisticated attack." He said the company would release additional details on possible recovery methods in the future.

"We are doing everything we can right now. However, this will take time," Kobal said.

Thief image via Shutterstock