Huge spamming botnet injured but still alive

The Pushdo/Cutwail botnet was crippled by security researchers but is not dead yet

A botnet responsible for a significant amount of spam has been crippled but may reconstitute itself in a matter of weeks, according to vendor M86 Security.

The Pushdo or Cutwail network of hacked computers ranked in the top five or so botnets for spam, responsible for as much as 10 percent of all spam, said Ed Rowley, product manager for M86 Security. The spam often advertises fake software, so-called designer goods and questionable pharmaceutical products.

But security analysts with the computer security company LastLine took action last week, contacting ISPs that were hosting the command-and-control infrastructure for the botnet.

About 30 servers at eight hosting providers were found to be supporting Pushdo. LastLine contacted the ISPs, and about 20 of the servers were taken offline, according to itsblog. Some ISPs, however, were unresponsive.

Spam levels have dropped, Rowley said. LastLine's action "will almost certainly have a positive effect for two to three weeks," Rowley said. But "the spammers will be able to find other hosting providers where they will be able to get their systems up and running."

LastLine appears to have taken down parts of Pushdo and Cutwail, which work together, wrote Atif Mushtaq of FireEye's Malware Intelligence Lab, in a blog post. Pushdo is a Trojan. Once it infects a computer, it often downloads Cutwail, a piece of malware capable of spamming as well as downloading other bad programs.

Mushtaq confirmed LastLine's success. "After identifying the botnets in question it was very easy for me to go through my botlab logs and try to find leftover command and control servers. There was no doubt that many of the CnC servers were null routed. But as mentioned by LastLine, there were still some servers which were active and serving contents," he wrote.

And it's those active servers that remain a concern. As long as those servers are able to eventually contact the computers infected with Pushdo, it will be possible to resume spamming.

Pushdo has the ability to generate random domain names. If those domains are registered and activated, the botnet controllers can send new instructions to the hacked machines.

"Either way, they'll be up and at it again in the near future," Rowley said.

Send news tips and comments to jeremy_kirk@idg.com

Join the newsletter!

Or

Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.

Tags antispamLastLine

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

Jeremy Kirk

IDG News Service
Show Comments

Cool Tech

Toys for Boys

Family Friendly

Stocking Stuffer

SmartLens - Clip on Phone Camera Lens Set of 3

Learn more >

Christmas Gift Guide

Click for more ›

Brand Post

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Aysha Strobbe

Microsoft Office 365/HP Spectre x360

Microsoft Office continues to make a student’s life that little bit easier by offering reliable, easy to use, time-saving functionality, while continuing to develop new features that further enhance what is already a formidable collection of applications

Michael Hargreaves

Microsoft Office 365/Dell XPS 15 2-in-1

I’d recommend a Dell XPS 15 2-in-1 and the new Windows 10 to anyone who needs to get serious work done (before you kick back on your couch with your favourite Netflix show.)

Maryellen Rose George

Brother PT-P750W

It’s useful for office tasks as well as pragmatic labelling of equipment and storage – just don’t get too excited and label everything in sight!

Cathy Giles

Brother MFC-L8900CDW

The Brother MFC-L8900CDW is an absolute stand out. I struggle to fault it.

Luke Hill

MSI GT75 TITAN

I need power and lots of it. As a Front End Web developer anything less just won’t cut it which is why the MSI GT75 is an outstanding laptop for me. It’s a sleek and futuristic looking, high quality, beast that has a touch of sci-fi flare about it.

Emily Tyson

MSI GE63 Raider

If you’re looking to invest in your next work horse laptop for work or home use, you can’t go wrong with the MSI GE63.

Featured Content

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?