Biblio

The dependability of Cyber Physical Systems (CPS) solely lies in the secure and reliable functionality of their backbone, the computing platform. Security of this platform is not only threatened by the vulnerabilities in the software peripherals, but also by the vulnerabilities in the hardware internals. Such threats can arise from malicious modifications to the integrated circuits (IC) based computing hardware, which can disable the system, leak information or produce malfunctions. Such modifications to computing hardware are made possible by the globalization of the IC industry, where a computing chip can be manufactured anywhere in the world. In the complex computing environment of CPS such modifications can be stealthier and undetectable. Under such circumstances, design of these malicious modifications, and eventually their detection, will be tied to the functionality and operation of the CPS. So it is imperative to address such threats by incorporating security awareness in the computing hardware design in a comprehensive manner taking the entire system into consideration. In this paper, we present a study in the influence of hardware Trojans on closed-loop systems, which form the basis of CPS, and establish threat models. Using these models, we perform a case study on a critical CPS application, gas pipeline based SCADA system. Through this process, we establish a completely virtual simulation platform along with a hardware-in-the-loop based simulation platform for implementation and testing.

A Cyber Physical Sensor System (CPSS) consists of a computing platform equipped with wireless access points, sensors, and actuators. In a Cyber Physical System, CPSS constantly collects data from a physical object that is under process and performs local real-time control activities based on the process algorithm. The collected data is then transmitted through the network layer to the enterprise command and control center or to the cloud computing services for further processing and analysis. This paper investigates the CPSS' most common cyber security threats and vulnerabilities and provides countermeasures. Furthermore, the paper addresses how the CPSS are attacked, what are the leading consequences of the attacks, and the possible remedies to prevent them. Detailed case studies are presented to help the readers understand the CPSS threats, vulnerabilities, and possible solutions.

Cloud computing allows users to delegate data and computation to cloud service providers, at the cost of giving up physical control of their computing infrastructure. An attacker (e.g., insider) with physical access to the computing platform can perform various physical attacks, including probing memory buses and cold-boot style attacks. Previous work on secure (co-)processors provides hardware support for memory encryption and prevents direct leakage of sensitive data over the memory bus. However, an adversary snooping on the bus can still infer sensitive information from the memory access traces. Existing work on Oblivious RAM (ORAM) provides a solution for users to put all data in an ORAM; and accesses to an ORAM are obfuscated such that no information leaks through memory access traces. This method, however, incurs significant memory access overhead. This work is the first to leverage programming language techniques to offer efficient memory-trace oblivious program execution, while providing formal security guarantees. We formally define the notion of memory-trace obliviousness, and provide a type system for verifying that a program satisfies this property. We also describe a compiler that transforms a program into a structurally similar one that satisfies memory trace obliviousness. To achieve optimal efficiency, our compiler partitions variables into several small ORAM banks rather than one large one, without risking security. We use several example programs to demonstrate the efficiency gains our compiler achieves in comparison with the naive method of placing all variables in the same ORAM.