Agent-based Modeling of User Circumvention of Security

Security subsystems are often designed with flawed assumptions arising from system designers' faulty mental models. Designers tend to assume that users behave according to some textbook ideal, and to consider each potential exposure/interface in isolation. However, fieldwork continually shows that even well-intentioned users often depart from this ideal and circumvent controls in order to perform daily work tasks, and that "incorrect" user behaviors can create unexpected links between otherwise "independent" interfaces. When it comes to security features and parameters, designers try to find the choices that optimize security utility--except these flawed assumptions give rise to an incorrect curve, and lead to choices that actually make security worse, in practice. We propose that improving this situation requires giving designers more accurate models of real user behavior and how it influences aggregate system security. Agent-based modeling can be a fruitful first step here. In this paper, we study a particular instance of this problem, propose user-centric techniques designed to strengthen the security of systems while simultaneously improving the usability of them, and propose further directions of inquiry.