How to Get A+ on SSL Labs Test
Understanding SSL Labs Testing
SSL Labs, operated by Qualys, provides a free SSL server test that analyzes your website's SSL/TLS configuration and assigns a grade from A+ to F. This tool is the industry standard for assessing SSL implementation quality. Achieving an A+ rating demonstrates that your website implements best-practice security configurations and protects users with state-of-the-art encryption.
The SSL Labs test evaluates multiple aspects of your SSL configuration including certificate validity, protocol support, key exchange mechanisms, cipher strength, and various security features. The grading system is strict and regularly updated to reflect evolving security standards. An A+ rating requires perfect or near-perfect scores across all categories plus implementation of security best practices like HSTS.
Prerequisites for Testing
Before attempting to achieve an A+ rating, ensure your basic SSL setup is correct. You need a valid SSL certificate from a trusted certificate authority, properly installed on your web server with the complete certificate chain. Your certificate should not be expired or about to expire, and it should match your domain name exactly.
Access to your web server configuration is essential. You'll need to modify server settings to adjust TLS versions, cipher suites, and security headers. The specific configuration method depends on your server software (Apache, Nginx, IIS, etc.). If you're using shared hosting, check with your provider about which settings you can control.
Protocol Support Configuration
SSL Labs evaluates which SSL/TLS protocol versions your server supports. To achieve an A+ rating, you must disable outdated and vulnerable protocols while supporting modern secure versions. Disable SSL 2.0, SSL 3.0, TLS 1.0, and TLS 1.1 entirely. These protocols have known vulnerabilities and should never be enabled.
Enable TLS 1.2 and TLS 1.3. TLS 1.3 is the latest protocol version and offers improved security and performance. However, TLS 1.2 should also be enabled for compatibility with older clients that don't yet support TLS 1.3. The combination of TLS 1.2 and 1.3 provides optimal security while maintaining broad compatibility.
For Nginx servers, configure your ssl_protocols directive to specify only TLS 1.2 and 1.3. For Apache servers, use the SSLProtocol directive with similar restrictions. Test your configuration after making changes to ensure you haven't accidentally blocked legitimate users.
Cipher Suite Configuration
Cipher suites determine how encryption keys are exchanged and how data is encrypted. Weak ciphers compromise security, while overly restrictive configurations can break compatibility. SSL Labs examines your cipher suite configuration carefully, and proper configuration is essential for an A+ rating.
Prioritize cipher suites with forward secrecy (also called perfect forward secrecy or PFS). Forward secrecy ensures that even if your private key is compromised in the future, past communications remain secure. Cipher suites using ECDHE (Elliptic Curve Diffie-Hellman Ephemeral) or DHE (Diffie-Hellman Ephemeral) key exchange provide forward secrecy.
Disable weak and vulnerable ciphers including those using RC4, DES, 3DES, MD5, export-grade encryption, anonymous Diffie-Hellman, and null ciphers. Configure your server to prefer AES-GCM cipher suites, specifically AES-128-GCM and AES-256-GCM. ChaCha20-Poly1305 is also an excellent modern cipher suite.
The order of cipher suites matters. Configure your server to prefer its own cipher suite order rather than accepting the client's preference. This ensures clients always use the strongest cipher their capabilities allow. A well-configured cipher suite string might look like: ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305.
Certificate Configuration
Your SSL certificate must meet several requirements for an A+ rating. Use a 2048-bit or 4096-bit RSA key, or an ECDSA certificate with a 256-bit key. Certificates with 1024-bit keys are considered insecure and will result in a failing grade. Include the complete certificate chain in your server configuration, including intermediate certificates. Missing intermediate certificates can cause trust errors for some users.
Certificate transparency is increasingly important. Modern certificates should be logged in certificate transparency logs, and your server should serve Signed Certificate Timestamps (SCT). Most certificates issued today automatically include SCTs, but verify this in your SSL Labs report.
Ensure your certificate covers all domains and subdomains you use. Mismatched names will reduce your score. If you serve content from www.example.com and example.com, your certificate should cover both. Wildcard certificates or subject alternative names (SAN) can address this.
Implementing HSTS
HTTP Strict Transport Security (HSTS) is required for an A+ rating. HSTS instructs browsers to only connect to your site over HTTPS, preventing downgrade attacks and providing additional security. Without HSTS, your maximum grade is capped at A.
Implement HSTS by adding a header to your server configuration. The header should specify a max-age of at least 6 months (15768000 seconds), though 1 year (31536000 seconds) is recommended. Include the includeSubDomains directive to protect all subdomains. For maximum protection, add the preload directive and submit your domain to the HSTS preload list.
A complete HSTS header looks like: Strict-Transport-Security: max-age=31536000; includeSubDomains; preload. Add this header through your server configuration or application code. Be careful with preload, as removing your domain from the preload list is a slow process. Only use preload if you're certain you can maintain HTTPS indefinitely.
Additional Security Headers
While not directly graded by SSL Labs, implementing additional security headers demonstrates security awareness and protects users. Add the X-Content-Type-Options header set to nosniff to prevent MIME type sniffing attacks. Include the X-Frame-Options header set to DENY or SAMEORIGIN to prevent clickjacking.
Implement a Content Security Policy (CSP) to prevent cross-site scripting attacks. Start with a restrictive policy and gradually relax it as needed. Use the Referrer-Policy header to control what referrer information is sent with requests. Add the Permissions-Policy header to control which browser features your site can use.
Testing and Troubleshooting
After configuring your server, test your implementation at SSL Labs. Enter your domain and wait for the comprehensive report. The test takes several minutes as it evaluates multiple aspects of your configuration. Review each category of the report carefully.
If you don't receive an A+ rating, the report explains what needs improvement. Common issues include outdated TLS versions, weak cipher suites, missing HSTS, or certificate problems. Make the necessary adjustments and retest. Use our HTTP Security Analyzer tool for ongoing monitoring and alerts about configuration issues.
Remember that browser compatibility and security are sometimes at odds. While you want the strongest security possible, you also need to support legitimate users. Test your site with various browsers and devices after making configuration changes. Analytics data can help you understand your user base and make informed decisions about compatibility tradeoffs.
Maintaining Your A+ Rating
SSL security is not a one-time setup. Security standards evolve, new vulnerabilities are discovered, and best practices change. Retest your SSL configuration quarterly to ensure you maintain your A+ rating. Subscribe to security mailing lists to stay informed about new vulnerabilities affecting TLS.
Keep your server software updated. Security patches often address SSL/TLS vulnerabilities. Certificate authorities occasionally revoke compromised certificates, requiring immediate replacement. Monitor your certificate expiration date and renew well before expiration. Automated renewal tools can prevent certificate-related downtime.
An A+ rating from SSL Labs demonstrates your commitment to security and provides users with confidence that their data is protected. Combined with other security measures, strong SSL configuration is a crucial component of a comprehensive security strategy.