"This was a stealth miner, designed to avoid detection by staying below the radar of both users and security tools," security researcher Himanshu Anand said.
The arrests of two men aged 19, a third aged 17 and a 20-year-old woman were made at their home addresses in London, Staffordshire, and the West Midlands, with support from West Midlands Regional Organised Crime Unit (Rocu) and the East Midlands Special Operations Unit.