Cross-site scripting (XSS) is a type of computer security vulnerability typically found in web applications that enables malicious attackers to inject client-side script into web pages viewed by other users. Because HTML documents have a flat, serial structure that mixes control statements, formatting, and the actual content, any non-validated user-supplied data included in the resulting page without proper HTML encoding, may lead to markup injection.
To prevent from XSS attack, ZK component encodes any value that might be input by an user, such as the value of label and textbox, by escaping & and other unsafe characters. For example, the following statement is totally safe no matter what the value of
any_value might be:
However, there are still some notes worth to pay attention to.
The content Property of html and comboitem
The content property of the html and combitem components are designed to allow application to generate HTML content directly. In other words, it is not encoded. Thus, it is better to carry the value input by an user, unless it is encoded property. For example, if the value of
any_content is, in the following example, generated directly and vulnerable to XSS attack if it is the value provided by an user and without proper encoding.
XSS Prevention Cheat sheet
As the number of possible attacking methods seems overwhelming and is growing over time - making it hard to follow and understand each and every single method - the OWASP maintains a XSS Prevention Cheat Sheet providing a positive prevention model of attacks even without knowing all the details of every single exploit.