The indictment says 500,000 computers in the United States were infected, including some used by educational institutions, nonprofit groups and government agencies like NASA.
Seven people were named in the indictment. Six Estonians were in custody in that country, and extradition was being sought, authorities said yesterday.
One Russian remained at large.
Federal prosecutors in Manhattan were to provide more details at a news conference.
The defendants "engaged in a massive and sophisticated scheme that infected at least 4 million computers located in over 100 countries with malicious software or malware," the indictment said.
"Without the computer users' knowledge or permission, the malware digitally hijacked the infected computers to facilitate the fraud."
Searches done on infected computers would be redirected to websites set up by the defendants to generate payments any time a user clicked on an advertisement, the indictment said. The doctored websites mimicked legitimate sites for Netflix, the IRS, ESPN, Amazon and others, it added.
The indictment estimated the defendants "reaped least USD 14 million in ill-gotten gains."