Lightweight and flexible trust assessment modules for the Internet of Things

In this paper we describe a novel approach to securely obtain measurements with respect to the integrity of software running on a low-cost and low-power computing node on demand. We propose to use these measurements as an indication of the trustworthiness of that node. Our approach is based on recent developments in Program Counter Based Access Control. Specifically, we employ Sancus, a light-weight hardware-only Trusted Computing Base and Protected Module Architecture, to integrate trust assessment modules into an untrusted embedded OS without using a hypervisor. Sancus ensures by means of hardware extensions that code and data of a protected module cannot be tampered with, and that the module's data remains confidential. Sancus further provides cryptographic primitives that are employed by our approach to enable the trust management system to verify that the obtained trust metrics are authentic and fresh. Thus, our trust assessment modules can inspect the OS or application code and securely report trust metrics to an external trust management system. We outline a prototypic implementation of our approach that integrates Sancus-protected trust assessment modules with the Contiki OS, running on a Sancus-enabled TI MSP430 microcontroller.status: publishe

There is safety in numbers: Preventing control-flow hijacking by duplication

Despite the large number of proposed countermeasures against control-flow hijacking attacks, these attacks still pose a great threat for today’s applications. The problem with existing solutions is that they either provide incomplete probabilistic protection (e.g., stack canaries) or impose a high runtime overhead (e.g., bounds checking). In this paper, we show how the concept of program-part duplication can be used to protect against control-flow hijacking attacks and present two different instantiations of the duplication concept which protect against popular attack vectors. First, we use the duplication of functions to eliminate the need of return addresses and thus provide complete protection against attacks targeting a function’s return address. Then we demonstrate how the integrity of function pointers can be protected through the use of data duplication. We test the combined effectiveness of our two methods and experimentally show that they provide an almost complete protection against control-flow hijacking attacks with only a low runtime overhead in real-world applications.status: publishe

Lightweight and flexible trust assessment modules for the Internet of Things

In this paper we describe a novel approach to securely obtain measurements with respect to the integrity of software running on a low-cost and low-power computing node autonomously or on request. We propose to use these measurements as an indication of the trustworthiness of that node. Our approach is based on recent developments in Program Counter Based Access Control. Specifically, we employ Sancus, a light-weight hardware-only Trusted Computing Base and Protected Module Architecture, to integrate trust assessment modules into an untrusted embedded OS without using a hypervisor. Sancus ensures by means of hardware extensions that code and data of a protected module cannot be tampered with, and that the module's data remains confidential. Sancus further provides cryptographic primitives that are employed by our approach to enable the trust management system to verify that the obtained trust metrics are authentic and fresh. Thereby, our trust assessment modules can inspect the OS or application code and securely report reliable trust metrics to an external trust management system. We evaluate a prototypic implementation of our approach that integrates Sancus-protected trust assessment modules with the Contiki OS running on a Sancus-enabled TI MSP430 microcontroller.status: publishe

Authentic execution of distributed event-driven applications with a small TCB

This paper presents an approach to provide strong assurance of the secure execution of distributed event-driven applications on shared infrastructures, while relying on a small Trusted Computing Base. We build upon and extend security primitives provided by a Protected Module Architecture (PMA) to guarantee authenticity and integrity properties of applications, and to secure control of input and output devices used by these applications. More specifically, we want to guarantee that if an output is produced by the application, it was allowed to be produced by the application’s source code. We present a prototype implementation as an extension of Sancus, a light-weight embedded PMA that extends the TI MSP430 CPU. Our evaluation of the security and performance aspects of our approach and the prototype show that PMAs together with our programming model form a basis for powerful security architectures for dependable systems in domains such as Industrial Control Systems, the Internet of Things or Wireless Sensor Networks.status: publishe

Secure Resource Sharing for Embedded Protected Module Architectures

Part 2: Secure Resource Sharing and Access ControlInternational audienceLow-end embedded devices and the Internet of Things (IoT) are becoming increasingly important for our lives. They are being used in domains such as infrastructure management, and medical and healthcare systems, where business interests and our security and privacy are at stake. Yet, security mechanisms have been appallingly neglected on many IoT platforms. In this paper we present a secure access control mechanism for extremely lightweight embedded microcontrollers. Being based on Sancus, a hardware-only Trusted Computing Base and Protected Module Architecture for the embedded domain, our mechanism allows for multiple software modules on an IoT-node to securely share resources. We implement and evaluate our approach for two application scenarios, a shared memory system and a shared flash drive. Our implementation is based on a Sancus-enabled TI MSP430 microcontroller. We show that our mechanism can give high security guarantees at small runtime overheads and a moderately increased size of the Trusted Computing Base

Secure resource sharing for embedded protected module architectures

© IFIP International Federation for Information Processing 2015. Low-end embedded devices and the Internet of Things (IoT) are becoming increasingly important for our lives. They are being used in domains such as infrastructure management, and medical and healthcare systems, where business interests and our security and privacy are at stake. Yet, security mechanisms have been appallingly neglected on many IoT platforms. In this paper we present a secure access control mechanism for extremely lightweight embedded microcontrollers. Being based on Sancus, a hardware-only Trusted Computing Base and Protected Module Architecture for the embedded domain, our mechanism allows for multiple software modules on an IoT-node to securely share resources. We implement and evaluate our approach for two application scenarios, a shared memory system and a shared flash drive. Our implementation is based on a Sancus-enabled TI MSP430 microcontroller. We show that our mechanism can give high security guarantees at small runtime overheads and a moderately increased size of the Trusted Computing Base.status: publishe

Protected software module architectures

status: publishe

ProSpeCT: Provably Secure Speculation for the Constant-Time Policy

Technical report for our paper accepted at the 32nd USENIX Security Symposium (2023), 56 pagesInternational audienceWe propose ProSpeCT, a generic formal processor model providing provably secure speculation for the constant-time policy. For constant-time programs under a non-speculative semantics, ProSpeCT guarantees that speculative and out-of-order execution cause no microarchitectural leaks. This guarantee is achieved by tracking secrets in the processor pipeline and ensuring that they do not influence the microarchitectural state during speculative execution. Our formalization covers a broad class of speculation mechanisms, generalizing prior work. As a result, our security proof covers all known Spectre attacks, including load value injection (LVI) attacks. In addition to the formal model, we provide a prototype hardware implementation of ProSpeCT on a RISC-V processor and show evidence of its low impact on hardware cost, performance, and required software changes. In particular, the experimental evaluation confirms our expectation that for a compliant constant-time binary, enabling ProSpeCT incurs no performance overhead