To fix the issue where subdomains don’t support HTTP Strict Transport Security (HSTS), follow these steps:
- Understand HSTS: HSTS is a web security policy mechanism that helps to protect websites against man-in-the-middle attacks by enforcing secure connections. It’s important to understand that HSTS settings are controlled by the HTTP response header named Strict-Transport-Security.
- Check Your Web Server Configuration: Ensure that your web server is configured to send the HSTS header. This configuration varies based on the web server you are using (like Apache, Nginx, IIS, etc.). You need to add specific directives to your server configuration to include the HSTS header in your HTTP responses.
- Enable HSTS for Subdomains: To ensure that all subdomains are included, you need to set the includeSubDomains directive in the HSTS header. For example, Strict-Transport-Security: max-age=31536000; includeSubDomains will enable HSTS for the domain and all its subdomains for one year.
- Set an appropriate max-age: The max-age directive specifies how long the browser should remember that this site and its subdomains should only be accessed using HTTPS. A long max-age may be beneficial for security but be cautious, as it commits you to support HTTPS for the specified amount of time.
- Test Your Configuration: Before enforcing HSTS on all users, test your configuration. You can initially set a low max-age and verify that your site and subdomains work correctly over HTTPS. Tools like SSL Labs’ SSL Test can help you check if HSTS is correctly implemented.
- Update DNS Records for Subdomains (if necessary): Ensure that all your subdomains are properly configured in your DNS settings. Each subdomain should have an SSL/TLS certificate installed and be accessible over HTTPS.
- Deploy and Monitor: After confirming that your setup works correctly, deploy the changes. Monitor your website and subdomains to ensure that there are no accessibility issues for users.
- Consider Preloading: Once you are confident in your HSTS implementation, you might consider adding your domain to the HSTS preload list, which is a list of domains hardcoded into browsers to be only accessible via HTTPS.
Who can Fix It:
- Web Developers: They play a crucial role in ensuring that the website and its subdomains are properly configured for HTTPS. Web developers may need to update the website’s code or configuration to support secure connections and to set the appropriate HSTS headers.
- System Administrators or DevOps Engineers: These professionals are responsible for configuring and maintaining the web servers (like Apache, Nginx, IIS, etc.). They will be the ones to update the server configurations to include the HSTS headers, and ensure that all subdomains have valid SSL/TLS certificates.
- Network Administrators: In some cases, especially in larger organizations, network administrators may be involved in managing DNS settings and ensuring that all subdomains are correctly configured and point to the right servers.
- Security Specialists: They are often consulted to ensure that the HSTS policy is appropriately implemented. Their expertise is crucial in determining the right max-age for the HSTS header and in deciding whether to include the domain in the HSTS preload list.
- IT Support Staff: They may assist in monitoring the deployment and handling any accessibility issues that arise post-implementation, especially in providing support to end-users who might experience issues accessing the site.