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 <A HREF="http://www.eweek.com/article2/0,1895,2034680,00.asp?kc=EWEWKEMLP102006BOE1">its own anti-virus scanner</A>--a level of complexity and sophistication that rivals some commercial software.