Microsoft Anti-Cross Site Scripting Library is an encoding library designed to help developers protect their ASP.NET web-based apps from XSS attacks. It differs from most encoding libraries in that it uses white-listing technique — sometimes referred to as principle of inclusions to provide protection against XSS attacks. This approach works by first defining a valid or allowable set of characters, and encodes anything outside this set (invalid characters or potential attacks).
The white-listing approach provides several advantages over other encoding schemes. New features include: – expanded white list that supports more languages – Performance improvements – Performance data sheets (in the online help) – Support for Shift_JIS encoding for mobile browsers – sample app – Security Runtime Engine (SRE) HTTP module – HTML Sanitization methods to strip dangerous HTML scripts.