eWeek reports: "SecureWorks anti-malware guru Joe Stewart is not one to be intimidated by advances in online crime activity. ... But, when he reversed the backend code associated with the Pushdo Trojan downloader, he discovered a modern malware distribution system fitted with complex tracking mechanisms and hiding techniques—another clear sign that virus fighters are up against a clever and sophisticated enemy."
Its almost shocking how sophisticated malware developers are getting. Some of the tracking systems are very complex.