Hundreds of legitimate Web sites have been hacked, spreading malware to visitors PCs. Hack may be related to 2007 break-in at U.K.-based hosting service Fasthosts Internet Ltd. Security experts say new tactic has made detection “extraordinarily difficult” Attackers are using a new tactic that has made it difficult to tell who else might be impacted, experts say. The sites identified by ScanSafe are legitimate URLs, many of them small mom-and-pop e-commerce sites. Most, although not all, are businesses located in the UK.”]