A piece of code that exploits a critical vulnerability that Microsoft issued a patch for only last week has been posted online, raising fears of an imminent MSBlast-style attack. On Feb. 10, Microsoft released a patch that fixes a networking flaw that affects all Windows XP, NT, 2000 and Server 2003 systems. The company warned people to patch their systems, because the vulnerability could be exploited by virus and worm writers. Four days after the patch was released, a piece of code was published on a French Web site that would let anyone exploit the vulnerability, meaning that unpatched customers...