Microsoft and Symantec joined forces to shut down a botnet controlling hundreds of thousands of computers on Wednesday, according to a report.
Between 300,000 and 600,000 computers were freed from botnet control when technicians and U.S. federal marshals seized a server in Weekhawken, N.J., and got another operator to disable a server in the Netherlands on Wednesday, reports Reuters.
The raid's target was the Bamital botnet, a click-fraud operation that first surfaced in 2010.
Users infected with Bamital malware had their search results unknowingly redirected to websites that profited from advertising impressions made by the visitors. The botnet's controllers may have also instructed infected computers to repeatedly click those advertisements, generating additional revenue.
Bamital potentially made $1 million or more annually for those involved, according to Microsoft and Symantec's estimates.
Computers infected with Bamital malware will now display a warning notification after making search queries alerting users their computer "is very likely to be infected by malware that redirects the results of your search queries." If you see this error message, it's a good idea to download and install free anti-malware tools provided by Microsoft and Symantec.src
Botnets, short for "robot network," are created by h*ckers who unleash malicious software that, when installed by an unsuspecting user, hands some or all control of infected computers to the h*cker. Aside from click-fraud schemes, they are often used for distributed denial of service (DDoS) attacks in which a massive amount of bogus traffic is directed at a target server in the hopes of knocking it offline.