Should smartphone users mock apps?

Smartphones represent the most serious threat to user privacy of any widely-deployed computing technology. Unfortunately, existing permission models provide smartphone users with limited protection, in part due to the difficulty users have distinguishing between legitimate and illegitimate use of their data. A mapping app may upload the same location information it uses to download maps (legitimate) to a marketing agency interested in delivering location-based ads (illegitimate). However, armed with the right technology users can turn apps' interest in personal data against them by intentionally manipulating the data that they expose. We refer to the intentional substitution of real data with artificial data intended to alter an apps perception of a user as mocking to differentiate this approach from other privacy-motivated techniques that focus on concealing data. In this paper, we explore the desirability and implications of this approach, present results from a survey suggesting that many users are interested in mocking apps, and discuss ethical and practical issues related to widespread app mocking.