Dubbed Dubbed 3ve, a sophisticated digital ad-fraud campaign allowed operators to earn tens of millions of dollars. FBI and cybersecurity firms dismantled a sophisticated ad fraud scheme that allowed its operators to make millions. Crooks used over 60,000 accounts selling ad inventory generating a record of 3 to 12 billion of daily ad bid requests. 3ve operated on a massive scale: at its peak, it controlled over 1 million IPs from both residential botnet infections and corporate IP spaces, primarily in North America and Europe.”]
Source: https://securityaffairs.co/wordpress/78515/malware/3ve-ad-fraud-operation.html