NiceHash website showing a maintenance message during security breach announcement

In a statement published on social media, NiceHash, a crypto-mining marketplace, said hackers breached its site and stole all the Bitcoin from its main wallet.

NiceHash is a service that allows users to register and rent or buy cryptocurrency mining/hashing power. Users can rent their own mining equipment (cloud computing servers) or they can rent mining equipment (cloud computing servers) from others, splitting profits.

Users can send earned currency in an external wallet, or they can store it in local "secure and insured BitGo Bitcoin deposit wallets" (as described on the NiceHash homepage).

Over $62.6 million stolen?

The hack appears to have affected the money stored locally, on the NiceHash network.

Based on the large number of posts in the NiceHash subreddit, the incident appears to have taken place earlier today, and many users complained about losing Bitcoin from their NiceHash wallets.

Site operators said they are still working to evaluate the total number of Bitcoin funds that were stolen, but users who had earnings stolen said Bitcoin funds were rerouted to a wallet address currently storing 4,736.42 Bitcoin — over $62,6 million at today's Bitcoin price ($13,450).

NiceHash users advised to change passwords

NiceHash says it reached out to "to the relevant authorities and law enforcement." The company's marketplace is currently down, showing a maintenance message.

Site operators advised users to change their passwords when the site returns online. Below is NiceHash's full statement.

Unfortunately, there has been a security breach involving NiceHash website. We are currently investigating the nature of the incident and, as a result, we are stopping all operations for the next 24 hours.

Importantly, our payment system was compromised and the contents of the NiceHash Bitcoin wallet have been stolen. We are working to verify the precise number of BTC taken.

Clearly, this is a matter of deep concern and we are working hard to rectify the matter in the coming days. In addition to undertaking our own investigation, the incident has been reported to the relevant authorities and law enforcement and we are co-operating with them as a matter of urgency.

We are fully committed to restoring the NiceHash service with the highest security measures at the earliest opportunity.

We would not exist without our devoted buyers and miners all around the globe. We understand that you will have a lot of questions, and we ask for patience and understanding while we investigate the causes and find the appropriate solutions for the future of the service. We will endeavour to update you at regular intervals.

While the full scope of what happened is not yet known, we recommend, as a precaution, that you change your online passwords.

We are truly sorry for any inconvenience that this may have caused and are committing every resource towards solving this issue as soon as possible.