In the past, the likes of torrent website PirateBay has grabbed headlines for mining cryptocurrencies with users hardware.

Adguard, makers of privacy and ad-blocking software, estimate that over a billion users have had malicious software installed on their computers, which is using processing power to mine cryptocurrency Monero.

According to RT, website Openload, Streamango, Rapidvideo and OnlineVideoConverter have been accused of mining cryptocurrencies while users watch videos.

By installing software on a user’s computer, the websites allow cybercriminals to mine Monero.

Adguard Co-founder Andrey Meshkov said they discovered the activity using their software:

“We came across several very popular websites that secretly use the resources of users’ devices for cryptocurrency mining. According to SimilarWeb, these four sites register 992 million visits monthly.”

According to Meshkov, a massive amount of Monero has been mined in a very short space of time.

“The total monthly earnings from crypto-jacking, taking into account the current Monero rate, could be as much as $326,000. These are simply outrageous figures.”

Monero is simply easier to mine

While Bitcoin is the most valuable cryptocurrency, it’s almost useless to try and mine the virtual currency without specialized hardware.

Malwarebytes’ Pieter Arntz says Monero is much easier to mine, making it the go-to currency for crypto jackers.

“Monero mining does not depend on heavily specialized, application-specific integrated circuits (ASICs), but can be done with any CPU or GPU. Without ASICs, it is almost pointless for an ordinary computer to participate in the mining process for Bitcoin.”

If you suspect your PC is being used to mine cryptocurrency - check out our guide.