However careful you’ve been when using Facebook up until now, it may be time to grow even more cautious.  New stats from BitDefender indicate that at least one out of five Facebook users have been exposed to threats via their news feeds.

That conclusion’s based on data from BitDefender’s Safego app, and may actually be conservative.  The data doesn’t cover whatever’s been sent through private messages, for example.  Plus, the 14,000 or so people who have downloaded the security-related app might be a little more paranoid than the average Farmville-obsessed individual, and they might have more security-conscious friends.

Still, Caroline McCarthy was able to report yesterday, "20 percent of Facebook users are exposed to malicious posts in their ‘news feeds’ of friends’ activity, generally defined as posts that, when clicked on, result in ‘the user’s account being hijacked and in malware being automatically posted on the walls of the respective user’s friends.’"

McCarthy later added, "Over 60 percent of attacks come from notifications from malicious third-party applications on Facebook’s developer platform."

That’s a serious cause for concern.  No one likes getting infected by a virus, and users and advertisers might grow a little less fond of Facebook if they ever start to feel like the site is making it too easy for malware authors to attack them.

On the other hand, these sorts of problems are difficult to escape.  Paul Wood, MessageLabs Intelligence Senior Analyst at Symantec, pointed out in an email to WebProNews, "Whatever methods of communication that mankind invents, sooner or later someone will find a way of taking advantage of the new invention and using it for illicit gain, whether this is for theft, confidence trickery or nuisance advertising."