Signing Me onto Your Accounts through Facebook and Google: a Traffic-Guided Security Study of Commercially Deployed Single-Sign-On Web Services Rui Wang Shuo Chen XiaoFeng Wang Indiana University Bloomington Microsoft Research Indiana University Bloomington Bloomington, IN, USA Redmond, WA, USA Bloomington, IN, USA
[email protected] [email protected] [email protected] Abstract— With the boom of software-as-a-service and social extensive commercial deployments as what happen on networking, web-based single sign-on (SSO) schemes are being today’s web, thanks to the increasing popularity of social deployed by more and more commercial websites to safeguard networks, cloud computing and other web applications. many web resources. Despite prior research in formal verification, little has been done to analyze the security quality Today, leading web technology companies such as of SSO schemes that are commercially deployed in the real Facebook, Google, Yahoo, Twitter and PayPal all offer SSO world. Such an analysis faces unique technical challenges, services. Such services, which we call web SSO, work including lack of access to well-documented protocols and code, through the interactions among three parties: the user and the complexity brought in by the rich browser elements represented by a browser, the ID provider (a.k.a, IdP, e.g., (script, Flash, etc.). In this paper, we report the first “field Facebook) and the relying party (a.k.a, RP, e.g., Sears). Like study” on popular web SSO systems. In every studied case, we any authentication scheme, a secure web SSO system is focused on the actual web traffic going through the browser, and used an algorithm to recover important semantic expected to prevent an unauthorized party from gaining information and identify potential exploit opportunities.