Bitcoin mining firm Cloudminr has become the latest cryptocurrency company to fall victim to cyber-criminals, with hackers holding its 80,000-strong user database to ransom for just 1 bitcoin (£185.36).
A sample of the database was posted to the Norwegian company's website, while other copies of the database were posted to online clipboards like Pastebin.
Cloudminr's website has since been taken offline, sparking fears from users that the operation was an elaborate Ponzi scheme.
The firm has said that it needs to create a new website "from scratch" as it fears that the hackers have left backdoors to its servers for future access.
"What we can tell now is that we have been hacked," the firm posted on Bitcoin Talk. "The hackers were able to access our source code and database, as well as editing it.
"Right now we cannot be sure that the payout addresses are the correct ones, as well as emails and other data. We do have backups but we need to know when exactly when the hackers gained access to our server."
Despite assurances that the site will be back online within the next few weeks, speculation on the Bitcoin Talk forum has centred around the idea that Cloudminr is a Ponzi scheme and will never relaunch.
Bitcoin mining review site Cloud Mining Directory has also downgraded Cloudminr's trust rating, after initially labelling it as one of the largest bitcoin cloud-mining companies in the industry.
The directory states: "I have had some concerns about cloudminr.io's corporate transparency, since they don't list a physical address on their website, they have never proven their hashing power, and they have only been in existence since October 2014.
"Cloudminr.io claims they have been hacked, and that is the reason their website is offline. However, it looks like this may have been a Ponzi scheme, and they will never come back online. Until they come back online, I am reducing trust rating to zero."
IBTimes UK was unable to contact Cloudminr for comment.