In which form of attack is alternate encoding, such as hexadecimal representation, most often observed?

Explanation

Cross site scripting (also known as XSS) occurs when a web application gathers malicious data from a user. The data is usually gathered in the form of a hyperlink which contains malicious content within it. The user will most likely click on this link from another website, instant message, or simply just reading a web board or email message.

Usually the attacker will encode the malicious portion of the link to the site in HEX (or other encoding methods) so the request is less suspicious looking to the user when clicked on.

For example the code below is written in hex:

href=javascript:alert&#

x28'XSS')>Click Here

is equivalent to:

Click Here

Note: In the format “&#xhhhh“, hhhh is the code point in hexadecimal form.