Web Security: XSS, CSRF & CORS
Web security involves protecting websites from threats like XSS, CSRF, and CORS vulnerabilities. XSS (Cross-Site Scripting) allows attackers to inject malicious scripts into web pages viewed by others. CSRF (Cross-Site Request Forgery) tricks users into executing unwanted actions on trusted sites. CORS (Cross-Origin Resource Sharing) is a security mechanism that controls how resources are accessed across different domains, helping prevent unauthorized data sharing or access.
Web Security: XSS, CSRF & CORS
Web security involves protecting websites from threats like XSS, CSRF, and CORS vulnerabilities. XSS (Cross-Site Scripting) allows attackers to inject malicious scripts into web pages viewed by others. CSRF (Cross-Site Request Forgery) tricks users into executing unwanted actions on trusted sites. CORS (Cross-Origin Resource Sharing) is a security mechanism that controls how resources are accessed across different domains, helping prevent unauthorized data sharing or access.
💡 Key Takeaways
- Understand what XSS, CSRF, and CORS are and how they differ in web security.
- Discover how XSS can inject malicious scripts into pages and identify defenses like output encoding, input validation, and Content Security Policy (CSP).
- Explore CSRF risks and how anti-CSRF measures such as tokens, SameSite cookies, and request validation help prevent unauthorized actions.
- Learn how CORS governs cross-origin requests, what the Access-Control headers mean, and best practices for securely configuring cross-origin access.
❓ Frequently Asked Questions
What is XSS (Cross-Site Scripting)?
A vulnerability that lets attackers inject and run malicious scripts in other users’ browsers when they view a vulnerable page. Types include stored, reflected, and DOM-based XSS.
How does CSRF (Cross-Site Request Forgery) work?
It tricks a user into performing unwanted actions on a site where they are authenticated, by submitting forged requests from another site or context.
What is CORS and why is it important?
Cross-Origin Resource Sharing is a browser policy that restricts cross-origin requests. Servers control allowed origins with headers; misconfig can expose data to unauthorized sites.
How can developers defend against XSS, CSRF, and CORS issues?
XSS: validate inputs, encode outputs, and use a Content Security Policy. CSRF: use anti-CSRF tokens and same-site cookies. CORS: configure strict allowed origins and avoid wildcards; validate origins.