Remember a hacker can easily save a copy of your webpage, then modify the HTML and javascript, then re-upload the page. Therefore, it is best to never use javascript alone for input validation since it can easily be removed, and instead duplicate any javacript validation with ASP validation. Also, hidden input fields are a threat in the same way since they can easily be altered to include bogus code. Other tips include: Never give away any clues about your database, including making your input field names the same as the database field names. Always set a max length for inputs and truncate the excess.