Not only on your computer, but when you visit websites. http://janecrypto.com/hackers-may-be-using-your-computer-to-make-bitcoin/ https://www.wsj.com/articles/hackers-latest-move-using-your-computer-to-mine-bitcoin-1509102002 older data- https://www.ophtek.com/detect-bitcoin-malware-on-your-pc/ Been going on for some time now. https://www.techworld.com/news/security/bitcoin-mining-function-embedded-inside-rogue-eulas-malwarebytes-warns-3491962/