Microsoft has emerged victorious from a sneak legal attack in which it managed to get 277 Internet domains associated with the Waledac botnet shut down, effectively cutting its owners off from their swarm of zombie infected PCs.
According to the company, Waledac was one of the 10 largest botnets in the United States, and had been responsible for over 1.5 billion spam email messages per day, with over 650 million of them directed at Hotmail accounts in the month of December alone. While the PCs still remain infected, they cannot receive commands to send out spam anymore. Security agencies reported that Waledac activity had largely wound down within three days of the domains shutting down.
The stealthy operation was codenamed B49 and took several months to coordinate, according to Microsoft's official blog post on the matter.