Securing modern web applications requires defense-in-depth across HTTP response headers, DOM sanitization, and strict cross-origin policies.
1. Essential Security Headers Configuration
| HTTP Header | Security Purpose | Recommended Directive |
|---|---|---|
Content-Security-Policy | Prevents XSS attacks by restricting resource execution | default-src 'self'; script-src 'self' 'nonce-...' |
X-Frame-Options | Prevents clickjacking in iframes | DENY or SAMEORIGIN |
Strict-Transport-Security (HSTS) | Enforces HTTPS connections exclusively | max-age=63072000; includeSubDomains; preload |