Addressing the unauthorized issuance of multiple TLS certificates for 1.1.1.1
Sep 4, 2025Joe Abley, Thibault Meunier, Vicky Shrestha, Bas Westerbaan
Summary
This post details the unauthorized issuance of TLS certificates for Cloudflare's 1.1.1.1 DNS resolver by Fina CA. It explains the mechanics of TLS certificate validation for DNS resolvers, the role of Certificate Transparency (CT) in detecting such misissuances, and the investigation into potential malicious use. The post emphasizes the security implications of CA negligence and the importance of robust CA security practices.
More from the Website Security & Threat Management trail
- We tested our own WAF with frontier AI models. Here’s what we found
- When scanners miss the attack: how Cloudflare Client-Side Security protects storefronts
- Introducing automatic remediation policies with Cloudflare CASB
- Introducing context-aware vulnerability discovery and remediation with Cloudflare Managed Defense and OpenAI Daybreak Models
- Introducing Adaptive Intelligence: undermining the economics of every bot attack