Pushdo botnet spams malware analysis site, researchers find

Saboteurs behind the Pushdo botnet are sending spam to a website meant to educate users on malware, researchers have found.

Blue Coat Systems researchers Chris Larsen and Jeff Doty co-authored a blog post on Wednesday, which detailed how the site,, was being targeted with Pushdo-related spam.

Since the malware appeared in 2007, Pushdo has been repeatedly used to deliver data-stealing trojans, like Zeus and SpyEye, via its spamming module Cutwail. And in this instance, the Pushdo bonet causes infected computers to spam out emails containing the trojan Zeus, researchers found. was set up to market a book of the same name written by Michael Sikorski and Andrew Honig. The book is meant to provide readers with a “hands-on guide to dissecting malicious software.”

In addition to spreading Zeus, Pushdo operators coded the malware so that infected computers running a malware monitoring tool called FakeNet  – which the authors of “Practical Malware Analysis” created and released with the book – spam the companion site with emails. FakeNet allows analysts to create a "fake" network capable of tracking malware.

In a Thursday follow-up email with, Doty wrote that he saw a spike in Pushdo infections on Aug. 26, which likely means a spam campaign was active that day to spread the malware. As of Wednesday afternoon, however, users were still downloading the malware, he said.

“After it compromises your machine, it starts to send out spam to all sorts of people,” Doty wrote of Pushdo. “That spam contains an attachment that is a Zeus payload."

[An earlier version of this story incorrectly stated that Pushdo attackers compromised the Practical Malware Analysis website, when instead, the botnet was used to spam the site.]

Get daily email updates

SC Media's daily must-read of the most current and pressing daily news

By clicking the Subscribe button below, you agree to SC Media Terms and Conditions and Privacy Policy.