Infamous Spam-Generating Botnet Taken Down

If you opened your inbox this morning to find fewer spam emails than normal, it may not be a coincidence. The infamous Rustock botnet, the world's most prolific source of spam emails, went silent on Wednesday morning and has yet to come back online.

The lack of recent noise from the malicious botnet is allegedly due to a coordinated effort initiated by Internet service providers and software vendors, according to the Wall Street Journal.

Cyber-security blogger Brian Krebs, who originally broke the story, said that it appears that anti-spam activists were able to successfully pull off the "largest botnet takedown in the history of the Internet" by knocking out all 26 of Rustock's command and control networks almost simultaneously.

Botnets like Rustock infect hundreds and thousands of computers around the world, which are then used to fire off spam emails without the knowledge of their owners. Rustock is well-known for delivering advertisements for discount Viagra and other drugs from unlicensed pharmacies. At its peak, Rustock was responsible for the circulation of 47.5 percent of all spam, according to Symantec (News - Alert).

"Normally, Rustock is sending between one to two thousands e-mails per second," a Canadian anti-spam activist, who asked to remain anonymous, told Krebs. "Today, we saw infected systems take an abrupt dive to sending about one to two emails per second."

Although the details of the takedown are still unclear, cyber-security experts have said that it must have taken a highly synchronized effort by ISPs to grind Rustock to an abrupt halt.

“They all had to have been taken down simultaneously or they would have noticed and been able to react,” John Bambenek, a member of the SANS global Internet monitoring service, told Digits.

While yesterday's apparent collapse of Rustcok is certainly good news, Krebs has urged everyone to hold off on celebrating. Rustock has gone offline in the past, only to come back even stronger.

Furthermore, computers that have been unknowingly spreading Rustock's spam are still infected with the malicious code. In previous takedown, botmasters have been able to regain control of these PCs. 

Beecher Tuttle is a TMCnet contributor. He has extensive experience writing and editing for print publications and online news websites. He has specialized in a variety of industries, including health care technology, politics and education. To read more of his articles, please visit his columnist page.

Edited by Juliana Kenny