"Cross site scripting (XSS) flaws are a relatively common issue in web application security, but they are still extremely lethal. They are unique in that, rather than attacking a server directly, they use a vulnerable server as a vector to attack a client. This can lead to extreme difficulty in tracing attackers, especially when requests are not fully logged (such as POST requests). Many documents discuss the actual insertion of HTML into a vulnerable script, but stop short of explaining the full ramifications of what can be done with a successful XSS attack."
- The Anatomy of Cross Site Scripting. ⊗