Security researchers from Damballa have found a new variant of the Pushdo malware that's better at hiding its malicious network traffic and is more resilient to coordinated takedown efforts. The Pushdo Trojan program dates back to early 2007 and is used to distribute other malware threats, like Zeus and SpyEye. It also comes with its own spam engine module, known as Cutwail, which is directly responsible for a large portion of the world's daily spam traffic.