Mark O'Neill

Mark O'Neill, Scott Heidbrink, Jordan Whitehead et al.

We describe TrustBase, an architecture that provides certificate-based authentication as an operating system service. TrustBase enforces best practices for certificate validation for all applications and transparently enables existing applications to be strengthened against failures of the CA system. The TrustBase system allows simple deployment of authentication systems that harden the CA system. This enables system administrators, for example, to require certificate revocation checks on all TLS connections, or require STARTTLS for email servers that support it. TrustBase is the first system that is able to secure all TLS traffic, using an approach compatible with all operating systems. We design and evaluate a prototype implementation of TrustBase on Linux, evaluate its security, and demonstrate that it has negligible overhead and universal compatibility with applications. To demonstrate the utility of TrustBase, we have developed six authentication services that strengthen certificate validation for all applications.

Mark O'Neill, Scott Ruoti, Kent Seamons et al.

The use of TLS proxies to intercept encrypted traffic is controversial since the same mechanism can be used for both benevolent purposes, such as protecting against malware, and for malicious purposes, such as identity theft or warrantless government surveillance. To understand the prevalence and uses of these proxies, we build a TLS proxy measurement tool and deploy it via Google AdWords campaigns. We generate 15.2 million certificate tests across two large-scale measurement studies. We find that 1 in 250 TLS connections are TLS-proxied. The majority of these proxies appear to be benevolent, however we identify over 3,600 cases where eight malware products are using this technology nefariously. We also find numerous instances of negligent, duplicitous, and suspicious behavior, some of which degrade security for users without their knowledge. Distinguishing these types of practices is challenging in practice, indicating a need for transparency and user awareness.