High Precision Laser Fault Injection using Low-cost Components

Abstract

This paper demonstrates that it is possible to executesophisticated and powerful fault injection attacks on microcontrollersusing low-cost equipment and readily available components.Earlier work had implied that powerful lasers and highgrade optics frequently used to execute such attacks were beingunderutilized and that attacks were equally effective when usinglow-power settings and imprecise focus.This work has exploited these earlier findings to develop a lowcostlaser workstation capable of generating multiple discretefaults with timing accuracy capable of targeting consecutiveinstruction cycles. We have shown that the capabilities of thisnew device exceed those of the expensive laboratory equipmenttypically used in related work.We describe a simplified fault model to categorize the effectsof induced errors on running code and use it, along with thenew device, to reevaluate the efficacy of different defensive codingtechniques. This has enabled us to demonstrate an efficient hybriddefense that outperforms the individual defenses on our chosentarget.This approach enables device programmers to select an appropriatecompromise between the extremes of undefended codeand unusable overdefended code, to do so specifically for theirchosen device and without the need for prohibitively expensiveequipment. This work has particular relevance in the burgeoningIoT world where many small companies with limited budgetsare deploying low-cost microprocessors in ever more securitysensitive roles