The success of Monday's takedown operation by law enforcement was credited to Internet Service Providers that helped victims avoid a disruption in service. Among the ISPs working with the FBI to locate infected computers and help users clean their systems were Comcast, Time Warner Cable and Verizon, .

Last November, police led by accused of running a four-year malware campaign that netted $14 million. The illicit operation at its height had infected 4 million computers globally, including 500,000 in the U.S., with the DNSChanger.

The malware redirected infected computers to rogue DNS servers that performed a number of illicit activities, including click fraud, redirecting searches to sites to generate ad fees and spreading fake antivirus products.

The FBI had planned to take down the gang's servers, which were based in the U.S., in March. That deadline was postponed until July 9 to give ISPs more time to work with affected customers. As of July 8, the number of infected computers had fallen to roughly 211,000, according to .

Nevertheless, that number included 12 percent of all Fortune 500 companies and 4 percent of "major" U.S. federal agencies, .