A US judge approved the firm’s request to shut down 277 internet domains, which it said were used to “command and control” the so-called Waledac botnet. A botnet is a network of infected computers under the control of hackers. The firm said that closing the domains would mean that up to 90,000 PCs would stop receiving orders to send out spam.
A recent study by the firm found that between 3-21 December “approximately 651 million spam e-mails attributable to Waledac were directed to Hotmail accounts alone”. It said it was one of the 10 largest botnets in the US.
Machines in a botnet have usually been infected by a computer virus or worm. Typically, users do not know their machine has been hijacked. Microsoft said that although it had successfully shut down the network, thousands of computers would still be infected with malware and advised people to run anti-virus software.
The court order was part of what was called “Operation b49“. Microsoft said it was the result of months of analysis and described it as a legal first. “This action has quickly and effectively cut off traffic to Waledac at the .comor domain registry level, severing the connection between the command and control centres of the botnet and most of its thousands of zombie computers around the world.”