The servers that once controlled the DNSChanger Trojan that infected millions of computers were taken down without incident. ISPs worked with the FBI to locate infected computers and help users clean their systems. The malware redirected infected computers to rogue DNS servers that performed a number of illicit activities, including click fraud, redirecting searches to generate ad fees and spreading fake antivirus products. The number of infected computers had fallen to roughly 211,000, but that number included 4 percent of “major” U.S. federal agencies.”]
Source: https://www.csoonline.com/article/2131935/isps-credited-with-dampening-dnschanger-s-impact.html