Understanding HTTP Security Headers

When a browser requests a web page, the server responds with HTTP headers alongside the HTML content. Security headers are specialized instructions that lock down browser behavior. Our tool analyzes your server's responses for critical headers including Content-Security-Policy, Strict-Transport-Security, X-Frame-Options, and X-Content-Type-Options, providing a comprehensive grade based on OWASP best practices.

Why Attackers Love Missing Headers

Without a strong Content Security Policy (CSP), attackers can inject malicious JavaScript (XSS) into your site to steal user session cookies or log keystrokes. Without X-Frame-Options, an attacker can embed your site in a hidden iframe on a malicious domain, tricking logged-in users into clicking buttons they didn't intend to (Clickjacking). Missing security headers essentially leave the browser's built-in defense mechanisms disabled.

Best Practices for Web Security

• Deploy a restrictive CSP: Start with a report-only policy to monitor violations, then enforce a strict policy that disallows unsafe-inline scripts.
• Enable HSTS with subdomains: Add the includeSubDomains and preload directives to your HSTS header for maximum protection.
• Prevent MIME-sniffing: Always set X-Content-Type-Options: nosniff to prevent browsers from executing non-executable file types as code.
• Control referrers: Use the Referrer-Policy header to prevent sensitive URLs (like password reset tokens) from leaking to third-party analytics scripts.