Guillaume Bouffard
Researcher in Embedded System Security
Vincent Giraud’s PhD thesis, titled “Application security on uncontrolled systems: Study of the risks, protections, stakes and interests around trust in off-the-shelf computer products”, is currently in progress at Ingénico hardware security labs. His thesis is co-supervised by David Naccache from ENS Paris, and it commenced in September 2020.
Service providers from a wide variety of domains, whether it is payments, identification, transportation, or others, are increasingly digitizing the assets they provide to end users. In practice, this results in a strong concentration of sensitive content (both data and executables) on people’s personal smartphones, for their private and work life simultaneously.
These types of systems, often called Commercial Off-The-Shelf devices (COTS), are under the control of end users. Industrial and state actors seeking trustworthy, stable execution environments thus face many challenges when trying to deploy solutions on them, as they do not necessarily have the possibility to exploit hardware security mechanisms, if any. Consequently, they sometimes try to develop software operating in the white-box security model, where everything has to operate under open scrutiny.
In this thesis, the general limits of such a paradigm are addressed. First, it is shown how the McEliece cryptosystem, and its asymmetrical algorithm with various advantages today, can be vulnerable in such a context by demonstrating an attack based on fault injection against it. Secondly, a focus is provided on the confidentiality guarantees provided by Android platforms. Specifically, by inspecting the implementation of power management in these platforms, it is demonstrated how a malicious application can spy on a legitimate one. A concrete example is given, focusing on the recovery of Personal Identification Numbers (PIN) codes entered in other software contexts. In both of these subjects, possible improvements and adjustments are nevertheless described.
These works intend to question the way security is envisioned on people’s COTS devices. These devices are under the responsibility of end users but can contain private parts based on secrets as roots of trust. The robustness of sensitive software thus depends on unfair parameters such as who is the developer, what the end users can afford, and what technical and personal choices they have made. A new distribution of security responsibilities is finally proposed.
Power Analysis Pushed too Far: Breaking Android-Based Isolation with Fuel Gauges- In Advances in Information and Computer Security - 18th International Workshop on Security, IWSEC 2023, Yokohama, Japan, August 29-31, 2023, Proceedings (2023) | |
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Efficient power management is critical for embedded devices, both for extending their lifetime and ensuring safety. However, this can be a challenging task due to the unpredictability of the batteries commonly used in such devices. To address this issue, dedicated Integrated Circuits (ICs) known as “fuel gauges” are often employed outside of the System- on-Chip (SoC). These devices provide various metrics about the available energy source and are highly accurate. However, their precision can also be exploited by malicious actors to compromise platform confidentiality if the Operating System (OS) fails to intervene. Depending on the fuel gauge and OS configuration, several attack scenarios are possible. In this article, we focus on Android and demonstrate how it is possible to bypass application isolation to recover Personal Identification Numbers (PINs) entered in other processes. |
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Faulting original McEliece’s implementations is possible How to mitigate this risk?- In IEEE European Symposium on Security and Privacy, EuroS&P 2023 - Workshops, Delft, Netherlands, July 3-7, 2023 (2023) | |
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Private and public actors increasingly encounter use cases where they need to implement sensitive operations on mass-market peripherals for which they have little or no control. They are sometimes inclined to attempt this without using hardware-assisted equipment, such as secure elements. In this case, the white-box attack model is particularly relevant and includes access to every asset, retro-engineering, and binary instrumentation by attackers. At the same time, quantum attacks are becoming more and more of a threat and challenge traditional asymmetrical ciphers, which are treasured by private and public actors. The McEliece cryptosystem is a code-based public key algorithm introduced in 1978 that is not subject to well-known quantum attacks and that could be implemented in an uncontrolled environment. During the NIST post-quantum cryptography standardization process [17], a derived candidate commonly refer to as classic McEliece was selected. This algorithm is however vulnerable to some fault injection attacks [7] while a priori, this does not apply to the original McEliece. In this article, we thus focus on the original McEliece cryptosystem and we study its resilience against fault injection attacks on an ARM reference implementation [18]. We disclose the first fault injection based attack and we discuss on how to modify the original McEliece cryptosystem to make it resilient to fault injection attacks. |
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Batterie à bord: quand les jauges de carburant dépassent les limites- In Symposium sur la sécurité des technologies de l’information et des communications (SSTIC), 7–9 june 2023, Rennes, France (2023) | |
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La gestion de l’alimentation est cruciale pour les périphériques embarqués. Cette tâche est complexe en raison des incertitudes liées aux batteries qui les alimentent. Elle est souvent confiée à des circuits intégrés dédiés, appelés jauges de carburant, qui sont précis et efficaces, mais peuvent également être utilisés pour des activités malveillantes qui mettent en danger la confidentialité de la plateforme. Dans cet article, nous montrons comment l’isolation inter-applications peut être contournée sur Android, en nous concentrant sur la récupération d’un code personnel d’identification entré sur un autre processus. |
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Fault attacks on whitebox computations- Journée thématique sur les attaques par injection de fautes (JAIF), 2022, Valence, France (2022) | |
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To perform sensitive operations, it is common to to use secure components: thanks to their various protections, they can protection, they can act as a root of trust. However, one may be forced to use alternative solutions as they are not available in all information systems. in all information systems. The industry deploy an approach based on software obfuscation, which is less software, which is less secure than those based on a hardware component. component. White-box cryptography is one of them: each intermediate step is precomputed and hidden, while the global semantics. Although it is purely software, hardware attacks could be transposed to it. be transposed to it. By instrumenting a program, one can by creating unexpected states in the program. unexpected states. As the needs of the industry are becoming more industry, research is now focusing on features such as such as resistance to quantum attacks and asymmetric and the asymmetric possibilities of cryptographic schemes. cryptographic schemes. These aspects are leading to the resurgence of specifications such as McEliece’s. In our work, we study the security of a cryptographic white box implementing implementing the McEliece algorithm and its resistance to attacks. In this talk, we will also also question the applicability in the software world of existing world of existing countermeasures used in hardware components. hardware components. |
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