Implementing Security Headers
Implementing Security Headers
HTTP security headers provide crucial additional protections beyond basic SSL/TLS encryption. HTTP Strict Transport Security (HSTS) forces browsers to use HTTPS connections exclusively, preventing protocol downgrade attacks and cookie hijacking. Implement HSTS with a sufficiently long max-age (at least 31536000 seconds or one year), include subdomains if all support HTTPS, and consider preload submission for maximum protection. Start with shorter durations for testing before committing to long periods.
Content Security Policy (CSP) headers protect against cross-site scripting (XSS) and injection attacks by controlling resource loading. While not exclusively an SSL feature, CSP works synergistically with HTTPS to provide comprehensive protection. Implement CSP gradually, starting with report-only mode to identify violations without breaking functionality. A basic CSP might include: Content-Security-Policy: default-src 'self'; script-src 'self' 'unsafe-inline'; style-src 'self' 'unsafe-inline'; img-src 'self' data: https:; upgrade-insecure-requests;
Additional security headers complement HTTPS protection. X-Frame-Options prevents clickjacking by controlling iframe embedding. X-Content-Type-Options stops MIME type sniffing that could execute malicious content. Referrer-Policy controls information leakage through referrer headers. Feature-Policy (now Permissions-Policy) restricts browser feature access. Implement these headers systematically, testing impact on functionality while improving security posture.
Certificate pinning through Public Key Pinning (HPKP) headers provides protection against fraudulent certificates but requires extreme caution. Incorrect pinning configuration can make sites inaccessible for extended periods. Most organizations should avoid HPKP due to the risk of self-inflicted denial of service. Instead, monitor Certificate Transparency logs for unauthorized certificates and implement CAA (Certificate Authority Authorization) DNS records to restrict which CAs can issue certificates for your domains.