When Good Services Go Wild: Reassembling Web Services for Unintended Purposes

The rich nature of modern Web services and the emerging “mash-up” programming model, make it difficult to predict the potential interactions and usage scenarios that can emerge. Moreover, while the potential security implications for individual client browsers have been widely internalized (e.g., XSS, CSRF, etc.) there is less appreciation of the risks posed in the other direction—of user abuse on Web service providers. In particular, we argue that Web services and pieces of services can be easily combined to create entirely new capabilities that may themselves be at odds with the security policies that providers (or the Internet community at large) desire to enforce. As a proof-of-concept we demonstrate a fully-functioning Web proxy service called CloudProxy. Constructed entirely out of pieces of unrelated Google and Facebook functionality, CloudProxy effectively launders a user’s connection through these provider’s resources.