Cross-site scripting(XSS) is a type of computer security vulnerability tipically found in Web application. XSS enables attackers to inject client-side scripts into Web pages viewed by other users. A cross-site scrpiting vulnerability may be used by attckers to bypass access controls such as same-origin policy. This rule detects XSS via event handlers, such as onerror. This rule supports to defend the A3: Injection of OWASP Top 10 - 2021. Other reference:None