XSS – ASP.NET Secure Coding

Using Microsoft Anti XSS Library

1. Download the AntiXss Library(AntiXSSLibrary.dll) from the Microsoft Web Protection Library.
2. Right click the References node of the project to add a reference to the assembly.
3. On particular cases :

Case #1

HTML escape before inserting untrusted data into HTML element content

string safedata = Microsoft.Security.Application.AntiXss.HtmlEncode( Request.QueryString[ "input" ] );
Response.Write(“<div>” + safedata + “</div>”);

Case #2

Attribute escape before inserting untrusted data into HTML common attributes

string safedata = Microsoft.Security.Application.AntiXss.HtmlAttributeEncode( Request.QueryString[ "input" ] );
Response.Write(‘<div name=”’ + safedata + ‘“>’);

Case #3

JavaScript escape before inserting untrusted data into HTML JavaScript data values

string safedata = Microsoft.Security.Application.AntiXss.JavaScriptEncode( Request.QueryString[ "input" ] );
Response.Write(“<script>alert(‘“+safedata+”’);</script>”);

References
http://msdn.microsoft.com/en-us/library/ff649310.aspx
http://msdn.microsoft.com/en-us/library/aa973813.aspx
http://wpl.codeplex.com/releases/view/80289