There have been at least three dozen heists of cryptocurrency exchanges since 2011; numerous hacked exchanges later shut down, most notably Mt. Gox, which was the world's largest bitcoin trading exchange when it went under in 2014.
"Importantly, our payment system was compromised and the contents of the NiceHash Bitcoin wallet have been stolen". We are now investigating the nature of the incident and, as a result, we are stopping all operations for the next 24 hours.
At the time of writing, Bitcoin is just $25 away from breaking the $15,000 milestone. The value of all cryptocurrencies, including bitcoin, now stands at about $415 billion, according to Coinmarketcap.
A company in Slovenia that mines bitcoin says it has been hacked, for a potential loss of tens of millions of dollars.
Cboe Global Markets has said it will start trading bitcoin futures on December 10, while CME Group's contracts are set to debut on December 18. Such currencies are not tied to a bank or government and allow users to spend money anonymously.
Many other users responded to the company's maintenance tweet, saying that they had money stolen. They are basically lines of computer code that are digitally signed each time they are traded. Others say they can be helpful methods of payment, such as in crisis situations where national currencies have collapsed.
Because the tally of bitcoin transactions, or blockchain, is verified constantly by a network of miners, rogues can not spend the same bitcoin twice.
The site's administrators are also recommending users change any shared passwords they used on NiceHash.
"Unfortunately, there has been a security breach involving NiceHash website".
"Investigation is very intensive at the moment but we can not talk about it in detail", Deputy Director of the Criminal Police Department Bostjan Lindav told reporters.