Microsoft says it helped take down a botnet that was distributing billions of spam emails by prosecuting its operators.

The software giant says that its legal action led to police raids on hosting providers across the US. These raids successfully disconnected the systems controlling the botnet.

Known as ‘Rustock’, the botnet consisted of as many as one million infected PCs, Microsoft said.

Microsoft is interested in combating botnets as many of them target its Windows operating system, and it is increasingly using legal, as well as technical, means to do so.

In February 2010, the company said it had disabled the ‘Waledac’ botnet by winning a court injunction to disconnect its control system.