Active Server Pages/Protecting against user-input (XSS attacks)
To protect your users from Cross-site scripting (XSS) and similar attacks, you should escape both URLs and user-submitted text. In ASP this is done with two functions Server.HTMLEncode, and Server.URLEncode.
Don't ever output non-escaped user data:
Response.write user_data 'not safe
Instead do the following:
Response.write Server.HTMLEncode( user_data )
This method should also be used for all data that comes from SQL. Better safe than sorry.
To encode URLs that you insert into the href attribute of A tags, use the Server.URLEncode function, like this:
<a href="http://foobar.com?<%= Server.URLEncode( "foo=bar" + "&baz=quz" ) %>">