Mining and research on security vulnerabilities of HTML functions in websites

With the rapid development of Web technologies, HTML functions are increasingly widely used in Web applications. However, the security issues of HTML functions have also emerged, becoming a major hidden danger in cybersecurity. This paper aims to systematically explore and study the security vulnerabilities of HTML functions in Web websites. Through actual case analysis, we demonstrate how to use the oncopy event to manipulate users' clipboard content to achieve potential attacks. The research results show that these vulnerabilities are widespread in existing Web applications and can be easily exploited maliciously, leading to user information leakage and system damage. Through in-depth research on these vulnerabilities, we have proposed a series of effective protective measures and best practices to help developers improve security when writing HTML code.