Legitimate Web sites are increasingly becoming unwitting sources of malware, according to PC World. Security experts report that Expedia.com and music site Rhapsody.com have been serving up banner ads that attempt to get visitors to download fake antispyware.

At Expedia.com, a banner with malware has tried to direct anyone who clicks on it to a site to install a Trojan.

An Expedia spokesperson said that the ads have been removed, and that the company is investigating how long they were online.

A report by WebSense claims that 51 percent of sites it classified as malicious in the second half of 2007 had been compromised by attack code. The remaining 49 percent were intentionally designed to propagate malware.

PC World reports that in the same week, Web sites for the Embassy of Ukraine in Lithuania and the Embassy of the Netherlands in Russia were found to be compromised and serving up attack codes to visitors.