Defensio, which Websense acquired last year, was launched as a service to stop blog comment spam. Now, version 2.0 features integration with Facebook and with Websense's Threat Seeker honeynet. Users linking it to their Facebook accounts can stop malicious links to malware from being posted before they appear.

The system works by analyzing links in Facebook and other websites as users click on them, gaining intelligence about the site in real time. It uses nine points of reputation to help analyze URLs, including lexical and search reputation, history, age, geography, and neighboring properties on the hosting company's servers.

"The Defensio application helps organizations protect their brand reputation and their 'fans' from spam or malicious content on their corporate Facebook pages," said Websense.

Facebook has become a popular target for malicious applications. Various versions of the Koobface worm have emerged that spread themselves by posting malicious links on Facebook users' walls. Researchers have also found several legitimate Facebook applications that have been hacked, often using HTML-based IFRAME tags to direct browsers to malicious content. Several of these applications were hacked by compromising software on the developers' own PCs, it was found.