RV here again…
Line 8, the username is directly being used to output the message. The following code fixes the vulnerability.
In this case, we are data binding data from a database.
Line 7-9 are vulnerable to XSS. Fortunately there is a very simple way to fix, which is shown below.
Also, please note that DataBinder.Eval and Eval are slow as they use reflection to parse the expression. A better option is to use the Container.DataItem directly as it is a DataRowView object.
Line 4 has the vulnerability. Anytime you use .NET variables or data directly into java script, that is a perfect recipe for a disaster. In fact, this vulnerability is so dangerous that neither ASP.NET Request Validation nor Server.HtmlEncode cannot protect you. Only AntiXss has native java script encoding.
We have seen three most common examples but there are many other vulnerable ways. The following is the small list of properties which could return untrusted input. By no means these values should be trusted, they should be validated and encoded during output.
|Class name and property|
Please note that there are other ways in which you can get user input and could result in a XSS attack. The best strategy is to identify user inputs and encode them before sending back to the browser.