First Rustock and Waledac. And now Kelihos.

Microsoft says it has taken down another botnet, this one called Kelihos code named “Operation b79.”

Microsoft, in a complaint (pdf, 34 pages) in federal court related to the botnet, names Dominique Alexander Piatti, dotFREE Group SRO and John Does 1-22 as the owners of a domain used to register other subdomains to operate the Kelihos botnet.

In a blog post, Richard Domingues Boscovich, an attorney with Microsoft Digital Crimes Unit, issued a stern warning:

The Kelihos takedown is intended to send a strong message to those behind botnets that it’s unwise for them to simply try to update their code and rebuild a botnet once we’ve dismantled it. When Microsoft takes a botnet down, we intend to keep it down – and we will continue to take action to protect our customers and platforms and hold botherders accountable for their actions.

Microsoft recently won a civil case against the Rustock botnet operators and turned the evidence it gathered over to the FBI for a possible criminal case.

In March, Microsoft said it brought down Rustock, a notorious international botnet the company says was responsible for sending billions of spam messages with pitches for Viagra and other prescription drugs. At its peak, the botnet was capable of sending out 30 billion spam emails a day.