Microsoft won its civil suit against the ringleaders of malware called Rustock but have still not caught the perpetrators and is turning all of the evidence it gathered in its investigation to the FBI for a possible criminal case, the company said Thursday.
The Rustock malware is known as a botnet. Botnets implant malicious software on people’s computers, forming a network that sends out spam or viruses.
Microsoft sued the people behind Rustock in the U.S. District Court of Western Washington. The company took out ads in Russian newspapers in June to notify the Rustock operators about the lawsuit. Microsoft won a temporary restraining order and seizure order in court, and the U.S. Marshal Service seized Rustock servers in Seattle, Chicago, Dallas, Kansas City, Scranton, Denver and Columbus in March. Because of the seizure, the botnet was no longer being used to send spam email.
Microsoft said Thursday that it is continuing to clean up the computers infected by Rustock malware and as of September 13, it estimated that the Rustock botnet had decreased in size by almost 75 percent since the takedown in March.
Microsoft had offered a $250,000 reward for information that leads to the arrest and conviction of Rustock’s operators. That reward offer remains in effect, but Microsoft says any tips should now be sent directly to the FBI at MS_Referrals@ic.fbi.gov.