BiasP

Abstract

Dynamic Voltage and Frequency Scaling (DVFS) plays an integral role in reducing the energy consumption of mobile devices, meeting the targeted performance requirements at the same time. We examine the security obliviousness of CPUFreq, the DVFS framework in Linux-kernel based systems. Since Linux-kernel based operating systems are present in a wide array of applications, the high-level CPUFreq policies are designed to be platform-independent. Using these policies, we present BiasP exploit, which restricts the allocation of CPU resources to a set of targeted applications, thereby degrading their performance. The exploit involves detecting the execution of instructions on the CPU core pertinent to the targeted applications, thereafter using CPUFreq policies to limit the available CPU resources available to those instructions. We demonstrate the practicality of the exploit by operating it on a commercial smartphone, running Android OS based on Linux-kernel. We can successfully degrade the User Interface (UI) performance of the targeted applications by increasing the frame processing time and the number of dropped frames by up to 200% and 947% for the animations belonging to the targeted-applications. We see a reduction of up to 66% in the number of retired instructions of the targeted-applications. Furthermore, we propose a robust detector which is capable of detecting exploits aimed at undermining resource allocation fairness through malicious use of the DVFS framework.