I found this on E-Week.com and thought that it was pretty interesting!
Veteran malware researcher Joe Stewart was fairly sure he'd seen it all until he started poking at the SpamThru Trojan—a piece of malware designed to send spam from an infected computer.
The Trojan, which uses peer-to-peer technology to send commands to hijacked computers, has been fitted with its own anti-virus scanner—a level of complexity and sophistication that rivals some commercial software.
"This the first time I've seen this done. [It] gets points for originality," says Stewart.
"It is simply to keep all the system resources for themselves—if they have to compete with, say, a mass-mailer virus, it really puts a damper on how much spam they can send," he added.
The full story here!