Spam levels fluctuate as crooks try to revive botnets

While spam initially slid off a digital cliff, two weeks later it's unclear whether spammers have resumed their usual practices.

Two weeks after a hosting firm's shutdown sent global spam volumes plummeting, some researchers continue to claim that junk mail rates remain dramatically down, while others say spam has already bounced back.

The shutdown of California-based McColo, a company that hosted a staggering variety of cybercriminal activity, on Nov. 11 cut spam by as much as 75 percent in the first few days after its upstream Internet providers pulled the plug. The shutdown slashed spam volumes because some of the planet's biggest spam-sending botnets were controlled from servers hosted by McColo, according to security researchers who had long urged the company's disconnection from the Web.

While spam initially slid off a digital cliff, two weeks later it's unclear whether spammers have resumed their usual practices.

A researcher with IronPort Systems, a messaging security company owned by Cisco Systems, today said that spam is still down, if not out. According to IronPort, Tuesday's spam volume was approximately 72.7 billion messages, less than half of the 153 billion on Nov. 11, but up from the 64.1 billion of Nov. 13, two days after McColo went off the air.

"We're seeing small spikes in spam volumes relative to the post-McColo shutdown volumes," said Nick Edwards, a senior product manager at IronPort, in an e-mail Tuesday explaining the uptick. "We believe the spammers are trying other botnets -- those whose command-and-control infrastructure and front-end applications were not hosted by McColo."

They're not having much luck, Edwards added. "Spam volumes are still down significantly," he said. "While there was a temporary increase in spam volume [last] Friday and Saturday, spam volumes have not approached levels prior to the McColo shut down. The spammers are having a difficult time finding a botnet for lease that they can use effectively."

Researchers at rival MessageLabs Group -- now part of Symantec -- see the situation differently.

According to Matt Sergeant, a senior anti-spam technologist at the company, spam levels have bounced back to about two-thirds of what they were before McColo was yanked off the Internet. In fact, spam jumped to that volume only today.

Sergeant wasn't surprised by the lag time between McColo's shutdown and a return of spam. "The Asprox and Rustock botnets are back with a vengeance after having found new command and control [servers]," Sergeant said in an e-mail. "Cutwail never went away and it seems its owners have used the opportunity to increase output. Mega-D is also on the rise again."

Sergeant and Edwards, however, agreed on one thing: The Srizbi botnet looks gone for good.

"Srizbi, having once been responsible for 50% of all spam, is now completely defunct," said Sergeant, who added that sans that botnet, "spam levels won't return to what they had been."

Edwards confirmed that Srizbi was still offline. "And we have confirmation that McColo traffic has not been re-hosted somewhere else," he added. "The backers of both are still scrambling." McColo was still unavailable as of mid-afternoon Tuesday.

Srizbi, which also goes by "Mailer Reactor," was among the world's biggest botnets. In April, noted botnet researcher Joe Stewart of SecureWorks estimated Srizbi as composed of 315,000 infected PCs. The McColo takedown, Stewart said last week, had cut off more than half a million compromised computers -- aka "bots" -- from their criminal controllers.

Join the PC World newsletter!

Error: Please check your email address.

Tags spammccolo

Our Back to Business guide highlights the best products for you to boost your productivity at home, on the road, at the office, or in the classroom.

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

Gregg Keizer

Computerworld
Show Comments

Essentials

Microsoft L5V-00027 Sculpt Ergonomic Keyboard Desktop

Learn more >

Lexar® JumpDrive® S57 USB 3.0 flash drive

Learn more >

Mobile

Lexar® JumpDrive® S45 USB 3.0 flash drive 

Learn more >

Exec

Audio-Technica ATH-ANC70 Noise Cancelling Headphones

Learn more >

Lexar® JumpDrive® C20c USB Type-C flash drive 

Learn more >

HD Pan/Tilt Wi-Fi Camera with Night Vision NC450

Learn more >

Lexar® Professional 1800x microSDHC™/microSDXC™ UHS-II cards 

Learn more >

Budget

Back To Business Guide

Click for more ›

Most Popular Reviews

Latest News Articles

Resources

PCW Evaluation Team

Michael Hargreaves

Windows 10 for Business / Dell XPS 13

I’d happily recommend this touchscreen laptop and Windows 10 as a great way to get serious work done at a desk or on the road.

Aysha Strobbe

Windows 10 / HP Spectre x360

Ultimately, I think the Windows 10 environment is excellent for me as it caters for so many different uses. The inclusion of the Xbox app is also great for when you need some downtime too!

Mark Escubio

Windows 10 / Lenovo Yoga 910

For me, the Xbox Play Anywhere is a great new feature as it allows you to play your current Xbox games with higher resolutions and better graphics without forking out extra cash for another copy. Although available titles are still scarce, but I’m sure it will grow in time.

Kathy Cassidy

STYLISTIC Q702

First impression on unpacking the Q702 test unit was the solid feel and clean, minimalist styling.

Anthony Grifoni

STYLISTIC Q572

For work use, Microsoft Word and Excel programs pre-installed on the device are adequate for preparing short documents.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?