Interscan Web Security Virtual Appliance (IWSVA) uses Trend Micro URL Filtering Engine (TMUFE) to filter URLs. If an accessed URL is not present in the TMUFE database, IWSVA uses Dynamic URL Categorization technology to perform real time categorization of the Web site based on the Web site content and HTTP URL.

Dynamic URL Categorization uses a pattern file that contains key words, rules and other information to filter out Web sites. The pattern file can be updated using Active Update.