Biblio

This paper demonstrates that it is possible to execute sophisticated and powerful fault injection attacks on microcontrollers using low-cost equipment and readily available components. Earlier work had implied that powerful lasers and high grade optics frequently used to execute such attacks were being underutilized and that attacks were equally effective when using low-power settings and imprecise focus. This work has exploited these earlier findings to develop a low-cost laser workstation capable of generating multiple discrete faults with timing accuracy capable of targeting consecutive instruction cycles. We have shown that the capabilities of this new device exceed those of the expensive laboratory equipment typically used in related work. We describe a simplified fault model to categorize the effects of induced errors on running code and use it, along with the new device, to reevaluate the efficacy of different defensive coding techniques. This has enabled us to demonstrate an efficient hybrid defense that outperforms the individual defenses on our chosen target. This approach enables device programmers to select an appropriate compromise between the extremes of undefended code and unusable overdefended code, to do so specifically for their chosen device and without the need for prohibitively expensive equipment. This work has particular relevance in the burgeoning IoT world where many small companies with limited budgets are deploying low-cost microprocessors in ever more security sensitive roles.

In the field of smartphones a number of proposals suggest that sensing the ambient environment can act as an effective anti-relay mechanism. However, existing literature is not compliant with industry standards (e.g. EMV and ITSO) that require transactions to complete within a certain time-frame (e.g. 500ms in the case of EMV contactless payments). In previous work the generation of an artificial ambient environment (AAE), and especially the use of infrared light as an AAE actuator was shown to have high success rate in relay attacks detection. In this paper we investigate the application of infrared as a relay attack detection technique in various scenarios, namely, contactless transactions (mobile payments, transportation ticketing, and physical access control), and continuous Two-Factor Authentication. Operating requirements and architectures are proposed for each scenario, while taking into account industry imposed performance requirements, where applicable. Protocols for integrating the solution into the aforementioned scenarios are being proposed, and formally verified. The impact on the performance is assessed through practical implementation. Proposed protocols are verified using Scyther, a formal mechanical verification tool. Finally, additional scenarios, in which this technique can be applied to prevent relay or other types of attacks, are discussed.