In this paper, we analyze the evolution of Certificate Transparency (CT) over time and explore the implications of exposing certificate DNS names from the perspective of security and privacy. We find that certificates in CT logs have seen exponential growth. Website support for CT has also constantly increased, with now 33% of established connections supporting CT. With the increasing deployment of CT, there are also concerns of information leakage due to all certificates being visible in CT logs. To understand this threat, we introduce a CT honeypot and show that data from CT logs is being used to identify targets for scanning campaigns only minutes after certificate issuance. We present and evaluate a methodology to learn and validate new subdomains from the vast number of domains extracted from CT logged certificates.
Scheitle et al. REF analyzed the server-side deployment of CT, and discussed the domain name information leakage caused by the certificates in public logs.
The Rise of Certificate Transparency and Its Implications on the Internet Ecosystem
Proceedings of the ACM Internet Measurement Conference (IMC), pp. 343-349, 2018
Computer Science