What is Certificate Transparency?
Certificate Transparency (CT) is a framework for monitoring and auditing SSL/TLS certificates. It requires Certificate Authorities to log every certificate they issue, making it possible to detect mis-issued or unauthorized certificates.
Use Cases
- Subdomain Discovery: Find all subdomains that have had certificates issued Find all subdomains that have been issued SSL certificates.
- Security Monitoring: Detect unauthorized certificate issuance Detect unauthorized certificates issued for your domain.
- Reconnaissance: Security professionals use CT logs to map an organization's infrastructure Security professionals use CT logs during penetration testing.
- Compliance: Verify that your organization's certificates are properly managed Verify that your organization's certificates are properly logged.
Frequently Asked Questions
How does CT help security?
CT logs make it possible to detect fraudulently issued certificates. If a CA issues a certificate for your domain without authorization, you can find it in CT logs.
Are all certificates logged?
Major browsers require CT logging for all publicly trusted certificates. Internal or private CA certificates may not be logged.