On Cache Timing Attacks Considering Multi-core Aspects in Virtualized Embedded Systems

Virtualization has become one of the most important security enhancing techniques for embedded systems during the last years, both for mobile devices and cyber-physical system (CPS). One of the major security threats in this context is posed by side channel attacks. In this work, Bernstein’s time-driven cache-based attack against AES is revisited in a virtualization scenario based on an actual CPS using the PikeOS microkernel virtualization framework. The attack is conducted in the context of the implemented virtualization scenario using different scheduler configurations. We provide experimental results which show that using dedicated cores for crypto routines will have a high impact on the vulnerability of such systems. We also compare the results to previous work in that field and our visualization directly shows the differences between cache architectures of the ARM Cortex-A8 and Cortex-A9. Further, a non-invasive countermeasure against timing attacks based on the scheduler of PikeOS is devised, which in fact increases the system’s security against cache timing attacks.