Most engineers know TLS certificates exist. Few know that every certificate ever issued is recorded in a public, searchable, append-only log, and that anyone can search it.
Certificate Transparency was designed to improve the security of the web's certificate infrastructure. As a side effect, it creates a permanent public record of infrastructure that developers often assume is private. That staging environment with no authentication. That internal tool on an obscure subdomain. That dev portal behind a domain nobody was supposed to know about.
Security by obscurity has always been a weak strategy. CT logs make it a nonexistent one.
In this session we'll cover how Certificate Transparency works, why it exists, and what it means for anything you've ever deployed behind a TLS certificate. We'll use real search tooling to find exposed infrastructure live, walk through two real examples of sensitive services discovered this way (including one that was responsibly disclosed and quietly taken down), and end with a practical framework for auditing your own domains before someone else does.
You'll leave knowing how to search CT logs, what to look for, and how to make better decisions about what should and shouldn't have a public certificate attached to it.
