Web Security: Finding and Preventing XSS Exploits

Cross-Site Scripting (XSS) remains one of the most common and dangerous vulnerabilities on the modern web. Understanding how malicious scripts are injected and executed is essential for anyone building or maintaining web applications today. This course helps you transition from a general understanding of web development to confidently identifying and neutralizing security flaws. You will learn the mechanics of various injection vectors and how to protect applications using modern defensive strategies. What you'll learn: Understand the foundational concepts of Stored, Reflected, and DOM-based XSS attacks; Identify vulnerable input fields and entry points within application source code; Implement robust input sanitization and output encoding using tools like DOMPurify; Leverage built-in security features and auto-escaping mechanisms in modern JavaScript frameworks; Configure a strong Content Security Policy (CSP) to mitigate injection risks; Practice testing techniques to safely discover security flaws in web interfaces. You will start with essential security terminology and browser safety models before moving on to practical code analysis and remediation strategies. The written material guides you step-by-step through analyzing code snippets and implementing secure alternatives. This course is designed for beginner developers, quality assurance testers, and aspiring security enthusiasts, requiring only a basic familiarity with HTML and JavaScript. Start reading today to build safer web applications and protect your users from malicious exploits.