Malicious software that exploits an unpatched vulnerability in Microsoft Corp.’s Windows operating system is now the most widely reported threat on the Internet, though it does not appear to be widely infecting corporate customers, according to McAfee Inc. In late December, hackers posted code that took advantage of the way Windows processes graphics files in the WMF (Windows Metafile) format, and that software is now being distributed in easy-to-use tools for creating malicious software that can be used to take over an unprotected computer, said Craig Schmugar, virus research manager at Santa Clara, Calif.-based McAfee. Full Story