Internet users are often encouraged to visit only legitimate Web sites to reduce the risk of malware infections, but distinguishing between legitimate and illegitimate Web sites increasingly appears to be meaningless.

Seventy percent of the top 100 Web sites either hosted malicious content or contained a link designed to redirect site visitors to a malicious Web site during the second half of 2008, claims Websense's report State of Internet Security, Q3-Q4, 2008.

That represents a 16% increase over the first half of 2008.

Perhaps more to the point, Websense says that 77% of Web sites with known malicious code are "legitimate" sites, calling into question the utility of any such designation of approval.

There are a variety of ways that brand-name sites can be compromised, including online iFrame injection services that rely on stolen logon information or SQL injection attacks.

Spam messages with malicious links can also lead to site compromises. According to Websense's report, almost 85% of e-mail messages were spam during the second half of 2008, and more than 90% of spam messages contained links to spam sites or malicious sites.

Only 6% of spam messages were phishing attempts, a 33% decrease from the first six months of 2008. Malware authors appear to be focusing more on data-stealing Trojans and DNS poisoning to accomplish their goals.

Porn-related spam surged 94% during the latter half of last year, a marketing gambit that appears to be consistent with porn industry poor-mouthing -- earlier this month, porn moguls made a show of stated plans to ask the U.S. government for a $5 billion financial bailout to shore up sagging sales. Porn spam, however, only represents 9% of the spam out there.