Building Trust for Smart Connected Devices: The Challenges and Pitfalls of TrustZone

Abstract

TrustZone-based Trusted Execution Environments (TEEs) have been utilized extensively for the implementation of security-oriented solutions for several smart intra and inter-connected devices. Although TEEs have been promoted as the starting point for establishing a device root of trust, a number of published attacks against the most broadly utilized TEE implementations request a second view on their security. The aim of this research is to provide an analytical and educational exploration of TrustZone-based TEE vulnerabilities with the goal of pinpointing design and implementation flaws. To this end, we provide a taxonomy of TrustZone attacks, analyze them, and more importantly derive a set of critical observations regarding their nature. We perform a critical appraisal of the vulnerabilities to shed light on their underlying causes and we deduce that their manifestation is the joint effect of several parameters that lead to this situation. The most important ones are the closed implementations, the lack of security mechanisms, the shared resource architecture, and the absence of tools to audit trusted applications. Finally, given the severity of the identified issues, we propose possible improvements that could be adopted by TEE implementers to remedy and improve the security posture of TrustZone and future research directions.

P4G2Go: A Privacy-Preserving Scheme for Roaming Energy Consumers of the Smart Grid-to-Go

“…The Trusted Execution Environment (TEE) [44] can be considered a sandbox capable of executing applications (named Trusted Applications). The isolation of the normal operating system from the TEE entails a secure environment, where applications of the normal world including malicious software are out of reach of sensitive data either stored in TEE or utilized by trusted applications.…”

“…However, the use of TEE hinders malware from executing arbitrary code and accessing the stored secret since TEE has the highest privileges in the OS. As a result, malware must also find an exploit to break TEE in order to read private information stored in the secure world [44]. On the other hand, the Idemix master secret being the equivalent of a private key, can be considered as a solution for non-repudiation (S3-Non-repudiation).…”

SealedGRID: Secure and Interoperable Platform for Smart GRID Applications

“…We decided to utilize the TrustZone TEE [ 28 ] for the SealedGRID platform, since it provides a wide range of functionality in isolated environments. Also, TrustZone is suitable for the use in low powered devices (IoT, smart meters etc.).…”

P2ISE: Preserving Project Integrity in CI/CD Based on Secure Elements

“…a smartphone), in an external element such as a flash memory card, in the circuitry of devices such as the SIM card itself used in mobile phones, or as a cloud service in Host Card Emulation technology. A new family of embedded environments known as Trusted Execution Environments (TEE) [25,26] has emerged. A TEE is a hardware environment with a secure operating system that is isolated and completely separated from the mobile platform.…”

“…For example, packet 1 may be 100 bytes starting at offset 0. Packet 2 may be 100 bytes starting at offset25. Packet 2 will overwrite 75 bytes of packet 1.…”