Trust No One Else: Detecting MITM Attacks against SSL/TLS without Third-Parties

The security guarantees provided by SSL/TLS depend on the correct authentication of servers through certificates signed by a trusted authority. However, as recent incidents have demonstrated, trust in these authorities is not well placed. Increasingly, certificate authorities (by coercion or compromise) have been creating forged certificates for a range of adversaries, allowing seemingly secure communications to be intercepted via man-in-the-middle (MITM) attacks. A variety of solutions have been proposed, but their complexity and deployment costs have hindered their adoption. In this paper, we propose Direct Validation of Certificates (DVCert), a novel protocol that, instead of relying on third-parties for certificate validation, allows domains to directly and securely vouch for their certificates using previously established user authentication credentials. By relying on a robust cryptographic construction, this relatively simple means of enhancing server identity validation is not only efficient and comparatively easy to deploy, but it also solves other limitations of third-party solutions. Our extensive experimental analysis in both desktop and mobile platforms shows that DVCert transactions require little computation time on the server (e.g., less than 1 ms) and are unlikely to degrade server performance or user experience. In short, we provide a robust and practical mechanism to enhance server authentication and protect web applications from MITM attacks against SSL/TLS.