PinUP: Pinning User Files to Known Applications

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William Enck
The Pennsylvania State University
United States

Patrick McDaniel
The Pennsylvania State University
United States

Trent Jaeger
The Pennsylvania State University
United States

Abstract:
Users commonly download, patch, and use applications such as email
clients, office applications, and media-players from the Internet. Such
applications are run with the user's full permissions. Because system
protections do not differentiate applications from each other, any
malcode present in the downloaded software can compromise or otherwise
leak all user data. Interestingly, our investigations indicate that
common applications often adhere to recognizable workflows on user data.
In this paper, we take advantage of this reality by developing
protection mechanisms that ``pin'' user files to the applications that
may use them. These mechanisms restrict access to user data to
explicitly stated workflows--thus preventing malcode from exploiting
user data not associated with that application. We describe our
implementation of PinUP on the Linux Security Modules framework, explore
its performance, and study several practical use cases. Through these
activities, we show that user data can be protected from untrusted
applications while retaining the ability to receive the benefits of
those applications.