KWAS Academy
Learn. Build. Master.
QUICK START:HTMLCSSJavaScriptTypeScriptPythonSQLReactNext.jsNode.jsDSASystem DesignDevOpsCybersecurityAI / ML
Intermediate 18 min readModule: Module 10: HTTP Security Headers (CSP, HSTS, CORS)

Content Security Policy (CSP) & HTTP Security Headers

Harden browsers against clickjacking, script injection, and protocol downgrade with CSP, HSTS, and X-Frame-Options.

What You Will Learn in This Lesson

  • Content-Security-Policy (CSP) headers to restrict script/image execution sources
  • HTTP Strict Transport Security (HSTS) to force HTTPS permanently
  • X-Frame-Options: DENY to prevent iframe clickjacking

Introduction & Core Concept

HTTP Security Headers are response headers sent by the server that instruct the client's web browser on how to behave securely when rendering the application.
WHY DOES THIS MATTER IN THE REAL WORLD?

A strict CSP header blocks unauthorized third-party scripts from executing even if an attacker successfully injects an XSS script tag!

Production Security Headers Configuration

http
http
1
2
3
4
Strict-Transport-Security: max-age=63072000; includeSubDomains; preload
X-Content-Type-Options: nosniff
X-Frame-Options: DENY
Content-Security-Policy: default-src 'self'; script-src 'self' https://trusted.cdn.com; img-src 'self' data: https:; object-src 'none';

Line-by-Line Technical Breakdown

1HSTS preload tells browsers to never attempt unencrypted HTTP connections to your domain.

Try It Yourself (Interactive Editor)

Modify the code in real-time and click Run to test live browser output and console logs.

Intelligent Code Runner & Live Sandbox[HTTP]
HTTP SOURCE EDITOR
Interactive Live Code

Industry Best Practices & Professional Standards

  • Deploy CSP in 'Content-Security-Policy-Report-Only' mode first to monitor violations before enforcement.

Lesson Summary & Core Takeaways

  • Security headers turn standard browsers into active defense shields.