New figures released by anti-virus firms McAfee and Symantec have shown the extent to which hackers are using cryptocurrency mining malware in attacks on consumers and businesses.

Cryptocurrency mining malware hijacks system resources and uses the processing power of infected computers to mine cryptocurrencies – Validating transactions so they can be added to the blockchain public ledger. This is achieved by solving difficult computational problems. The first person to solve the problem is rewarded with a small payment.

For cryptocurrency mining to be profitable, a lot of processing power is required. Using one computer for mining cryptocurrency will generate a few cents to a few dollars a day; however, hackers who infect thousands of computers and use them for cryptocurrency mining can generate significant profits for little work.

The use of cryptocurrency mining malware has increased considerably since Q4, 2017 when the value of Bitcoin and other cryptocurrencies started to soar. The popularity of cryptocurrency mining malware has continued to grow steadily in 2018. Figures from McAfee suggest cryptocurrency mining malware has grown by 4,000% in 2018.

McAfee identified 500,000 new coin mining malware in the final quarter of 2017. In the final quarter of 2018, the figure had increased to 4 million. Figures from Symantec similarly show the scale of the problem. In July 2018, Symantec blocked 5 million cryptojacking events. In December, the firm blocked 8 million.

There are many different ways of infecting end users. Hackers are exploiting unpatched vulnerabilities to silently download the malware. They package coin mining malware with legitimate software, such as the open-source media player Kodi, and upload the software to unofficial repositories.

One of the easiest and most common ways of installing the malware is through email. Spam emails are sent containing a hyperlink which directs users to a website where the malware is silently downloaded. Links are similarly distributed through messaging platforms such as Slack, Discord, and Telegram. One campaign using these messaging platforms included links to a site that offered software that claimed to fix coin mining malware infections. Running the fake software installer executed code on the computer which silently downloaded the malware payload.

Unlike ransomware, which causes immediate disruption, the presence of cryptocurrency mining malware may not be noticed for some time. Computers infected with coin mining malware will slow down considerably. There will be increased energy usage, batteries on portable devices will be quickly drained, and some devices may overheat. Permanent damage to computers is a possibility.

The slowdown of computers can have a major impact for businesses and can result in a significant drop in productivity if large numbers of devices are infected. Businesses that have transitioned to cloud computing that are charged for CPU usage can see their cloud bills soar.

Anti-virus software can detect known coin mining malware, but new malware variants will be unlikely to be detected. With so many new malware variants now being released, AV software alone will not be effective. It is therefore important to block the malware at source. Spam filters, such as SpamTitan, will help to prevent malicious emails from reaching end users’ inboxes. Web filters, such as WebTitan, prevent users from accessing infected websites, unofficial software repositories, and websites with coin-mining code installed that uses CPU power through browser sessions.