Foundations of Cross-Site Scripting: XSS Attacks and Defenses

Web applications are constantly targeted by malicious actors, and Cross-Site Scripting (XSS) remains one of the most prevalent vulnerabilities on the internet. Understanding how these security flaws occur is the first step toward building resilient web applications. This text-only course guides you from the fundamental concepts of web security to identifying and mitigating modern XSS vulnerabilities, helping you gain the practical knowledge needed to write secure code and protect user data. What you'll learn: - Understand the core mechanics of XSS, including how browsers parse and execute injected scripts. - Identify the differences between Stored, Reflected, and DOM-based XSS vulnerabilities. - Analyze vulnerable code patterns to pinpoint security flaws in web applications. - Implement robust defense mechanisms, including context-aware output encoding and input validation. - Configure modern security controls like Content Security Policy (CSP) to mitigate injection risks. - Leverage modern web framework protections to automatically escape untrusted data. You will begin by exploring the foundational concepts of web architecture, HTTP requests, and the Same-Origin Policy. From there, you will read through realistic attack scenarios, analyze vulnerable code examples, and study modern industry-standard mitigation strategies step by step. This course is designed for aspiring security analysts, web developers, and beginners curious about cybersecurity, requiring only a basic understanding of HTML and JavaScript. Start building your web security toolkit and learn how to defend applications against XSS attacks today.