A Principled Approach to Securing IoT Apps
Abstract: IoT apps are becoming increasingly popular as they allow users to manage their digital lives by connecting otherwise unconnected devices and services: cyberphysical “things” such as smart homes, cars, or fitness armbands, to online services such as Google or Dropbox, to social networks such as Facebook or Twitter. IoT apps rely on end-user programming, such that anyone with an active account on the platform can create and publish apps, with the majority of apps being created by third parties. We demonstrate that the most popular IoT app platforms are susceptible to attacks by malicious app makers and suggest short and longterm countermeasures for securing the apps. For short-term protection we rely on access control and suggest the apps to be classified either as exclusively private or exclusively public, disallowing in this way information from private sources to flow to public sinks. For longterm protection we rely on a principled approach for designing information flow controls. Following these principles we define projected security, a variant of noninterference that captures the attacker’s view of an app, and design two mechanisms for enforcing it. A static enforcement based on a flow-sensitive type system may be used by the platform to statically analyze the apps before being published on the app store. This enforcement covers leaks stemming from both explicit and implicit flows, but is not expressive enough to address timing attacks. Hence we design a second enforcement based on a dynamic monitor that covers the timing channels as well.
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