A tricky malicious program has become more prevalent in spam, but experts don't know what its creators plan to do with it. Many vendors are rating the malware--called "Warezov," "Stration," and "Stratio"--as a low risk. But they also say <A HREF="http://www.cio.com/blog_view.html?CID=26185">it is tricky to deal with.</A> The malware is a mass-mailing worm that affects machines running Microsoft's Windows OS.