Microsoft is warning that attackers are exploiting a critical unpatched Windows vulnerability using infected USB flash drives. The bug admission is the first that affects Windows XP Service Pack 2 (SP2) since Microsoft retired the edition from support , researchers said. When Microsoft does fix the flaw, it will not be providing a patch for machines still running XP SP2. In a security advisory, Microsoft confirmed what other researchers had been saying for almost a month: Hackers have been exploiting a bug in Windows "shortcut" files, the placeholders typically dropped on the desktop or into the Start menu to represent links to actual files or programs.(See also "The Ultimate Guide to Windows 7 Security.") "In the wild, this vulnerability has been found operating in conjunction with the Stuxnet malware," Dave Forstrom, a director in Microsoft's Trustworthy Computing group, said in a post Friday to a company blog . Stuxnet is a clan of malware that includes a Trojan horse that downloads further attack code, including a rootkit that hides evidence of the attack. Forstrom characterized the threat as "limited, targeted attacks," but the Microsoft group responsible for crafting antivirus signatures said it had tracked 6,000 attempts to infect Windows PCs as of July 15. On Friday, Siemens alerted customers of its Simatic WinCC management software that attacks using the Windows vulnerability were targeting computers used to manage large-scale industrial control systems used by major manufacturing and utility companies. http://www.pcworld.com/article/201347/microsoft_warns_of_zero_day_windows_ho...