Researcher: Two big botnets gone, but replacements step up

Srizbi, Storm dead, but Donbot and Xarvester add to spam resurgence

Although the shutdown of a California Web hosting company eradicated several prominent botnets last year, others have stepped up to fill the gaps, a security researcher said Friday.

Gone from the landscape, said Joe Stewart, director of research at SecureWorks, are "Srizbi" and "Storm," the botnets Stewart ranked as No. 1 and No. 5, respectively, in an April 2008 botnet census.

Srizbi, and to a lesser degree "Rustock," were crippled two months ago when McColo, a company that has long been hosting botnet command-and-control servers, was cut off from the Internet by its upstream providers after researchers accused it of harboring cyber-crime activity. Stewart was one of the researchers who had beaten the McColo drum.

When McColo's connection to the Internet was severed, spam volumes immediately plunged as spammers were unable to use Srizbi or Rustock bots to send their junk mail.

But the relief was short-lived. "There was a time when the bot numbers were diminishing, and we made up some ground," acknowledged Joe Stewart, director of research at SecureWorks. Now, however, other botnets have come into prominence. Some of them were well-known before the McColo take-down, but had been relatively small, while others have come out of obscurity.

The result? "Spam isn't quite up to the pre-McColo level, but it's easily within the 80 to 90 percent range," said Stewart, citing numbers consistent with other estimates. Symantec, for example, estimated this month's spam level at 80 percent of that before the McColo shut-down.

Botnets have rebounded for several reasons, most notably because they're profitable, said Stewart, who recently repeated his census of April to come up with a new ranking of botnets.

"Cutwail," the biggest beneficiary of the demise of Srizbi, took the top spot in Stewart's revised chart. It boasts an estimated 175,000 compromised PCs, up from 125,000 in April. "Cutwail's spam output actually increased shortly after [McColo], so it probably picked up some customers from other botnets," said Stewart.

As he did last year, Stewart estimated the botnet sizes by first "fingerprinting" each botnet with their implementations of SMTP (Simple Mail Transfer Protocol), then took a one-day spam traffic sample from each bot to extrapolate a total number of infected PCs in each botnet.

Although Rustock was also hit by the McColo shut-down, it was able to recover when Srizbi could not. Currently in the No. 2 spot, Rustock, controls approximately 130,000 computers, down from the 150,000 it "owned" last April.

Joining Cutwail and Rustock are a pair of new additions to Stewart's list. Until recently, both "Donbot" and "Xarvester" had been minor players in the spam-sending ecosystem. "We have noticed that some botnets picked up traffic significantly," said Stewart, who called out the two as botnets to monitor during 2009.

Join the newsletter!

Error: Please check your email address.
Rocket to Success - Your 10 Tips for Smarter ERP System Selection

Tags botnets

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Gregg Keizer

Computerworld
Show Comments

Cool Tech

Breitling Superocean Heritage Chronographe 44

Learn more >

SanDisk MicroSDXC™ for Nintendo® Switch™

Learn more >

Toys for Boys

Family Friendly

Panasonic 4K UHD Blu-Ray Player and Full HD Recorder with Netflix - UBT1GL-K

Learn more >

Stocking Stuffer

Razer DeathAdder Expert Ergonomic Gaming Mouse

Learn more >

Christmas Gift Guide

Click for more ›

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Walid Mikhael

Brother QL-820NWB Professional Label Printer

It’s easy to set up, it’s compact and quiet when printing and to top if off, the print quality is excellent. This is hands down the best printer I’ve used for printing labels.

Ben Ramsden

Sharp PN-40TC1 Huddle Board

Brainstorming, innovation, problem solving, and negotiation have all become much more productive and valuable if people can easily collaborate in real time with minimal friction.

Sarah Ieroianni

Brother QL-820NWB Professional Label Printer

The print quality also does not disappoint, it’s clear, bold, doesn’t smudge and the text is perfectly sized.

Ratchada Dunn

Sharp PN-40TC1 Huddle Board

The Huddle Board’s built in program; Sharp Touch Viewing software allows us to easily manipulate and edit our documents (jpegs and PDFs) all at the same time on the dashboard.

George Khoury

Sharp PN-40TC1 Huddle Board

The biggest perks for me would be that it comes with easy to use and comprehensive programs that make the collaboration process a whole lot more intuitive and organic

David Coyle

Brother PocketJet PJ-773 A4 Portable Thermal Printer

I rate the printer as a 5 out of 5 stars as it has been able to fit seamlessly into my busy and mobile lifestyle.

Featured Content

Product Launch Showcase

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?