Finally, some good news. The Rustock botnet was responsible for almost half of the world’s spam emails. So, when it was finally taken out, spam decreased by about 33%, according to a study by Symantec.

There was some inactivity by the Rustock botnet at the beginning of the year and no one knew why. Then Microsoft came out and said they took it out with the help of a couple other companies.

In case you don’t know what the Rustock botnet is, here is their Wikipedia entry:

The Rustock botnet was a botnet that operated from around 2006[1] until March 2011.

It consisted of computers running Microsoft Windows, and was capable of sending up to 25,000 spam messages per hour from an infected PC.[2][3] At the height of its activities, it sent an average of 192 spam messages per compromised machine per minute.[4] Reported estimates on its size vary greatly across different sources, with claims that the botnet may have comprised anywhere between 150,000 to 2,400,000 machines.[5][6][7] The size of the botnet was increased and maintained mostly through self-propagation, where the botnet sent many malicious e-mails intended to infect machines opening them with a trojan which would incorporate the machine into the botnet.[8]

“In the days following the botnet takedown on March 16, spam accounted for approximately 33 billion emails per day, compared with an average of 52 billion per day in the previous week,” Symantec found.

It’s not unusual for botnets to have periods of inactivity, and that’s what happened earlier this year. But, Rustock recovered, sending out some 14 billion spam emails a day. That’s really annoying to type, let alone read.

“It remains to be seen whether the criminals behind Rustock will be able to recover from this coordinated effort against what has become one of the most technically sophisticated botnets in recent years,” Symantec said in its report. “Rustock has been a significant part of the botnet and malware landscape since January 2006, much longer than any of its contemporaries.”

I’m sure these low-life criminals will find some other way to annoy the heck out of us.