Integrating Security in Resource-Constrained Cyber-Physical Systems

Abstract

Defense mechanisms against network-level attacks are commonly based on the use of cryptographic techniques, such as lengthy message authentication codes (MAC) that provide data integrity guarantees. However, such mechanisms require significant resources (both computational and network bandwidth), which prevents their continuous use in resource-constrained cyber-physical systems (CPS). Recently, it was shown how physical properties of controlled systems can be exploited to relax these stringent requirements for systems where sensor measurements and actuator commands are transmitted over a potentially compromised network; specifically, that merely intermittent use of data authentication (i.e., at occasional time points during system execution), can still provide strong Quality-of-Control (QoC) guarantees even in the presence of false-data injection attacks, such as Man-in-the-Middle (MitM) attacks. Consequently, in this work, we focus on integrating security into existing resource-constrained CPS, in order to protect against MitM attacks on a system where a set of control tasks communicates over a real-time network with system sensors and actuators. We introduce a design-time methodology that incorporates requirements for QoC in the presence of attacks into end-to-end timing constraints for real-time control transactions, which include data acquisition and authentication, real-time network messages, and control tasks. This allows us to formulate a mixed integer linear programming-based method for direct synthesis of schedulable tasks and message parameters (i.e., deadlines and offsets) that do not violate timing requirements for the already deployed controllers, while adding a sufficient level of protection against network-based attacks; specifically, the synthesis method also provides suitable intermittent authentication policies that ensure the desired QoC levels under attack. To additionally reduce the security-related bandwidth overhead, we propose the use of cumulative message authentication at time instances when the integrity of messages from subsets of sensors should be ensured. Furthermore, we introduce a method for the opportunistic use of the remaining resources to further improve the overall QoC guarantees while ensuring system (i.e., task and message) schedulability. Finally, we demonstrate applicability and scalability of our methodology on synthetic automotive systems as well as a real-world automotive case-study.

Intrusion Detection and Localization for Networked Embedded Control Systems

“…A body of existing work also explores enhancing security in legacy networks (e.g., based on CAN bus) by retrofitting of authentication services (e.g., [23]) or modifying the execution paradigm (e.g., [24]). All these works rely on the ability to perform some level of modification to the firmware executed by legacy ECUs (e.g., running additional security services, performing changes to real-time scheduling policies, etc.…”

Composite Resource Scheduling for Networked Control Systems

“…To perform an extensive comparison, we generate 1000 trials under each parameter setting. Each trial contains a task set T = {τ 1 , τ 2 , ..., τ n }, where n ∈ [1,50]. The task periods are randomly set in [10,10000].…”

“…However, the network scheduling is not guaranteed to be real-time because of the CAN protocol considered in the model. The work in [50] studies how to integrate security guarantees with end-toend timeliness requirements for control tasks in resourceconstrained NCSs. The proposed sensing-control-actuation model is similar to our CRS model, but the sensing, computing and actuating segments in the proposed model have designed release times and deadlines.…”

A Controllable False Data Injection Attack for a Cyber Physical System

“…Among many different CPS attacks, FDIA can be considered to be one of the most prominent attacks [5]. The FDIA injects a modified control input [13] or modified measurement [17] [18] or both [8] to degrade the performance of a control system. Even though FDIA was considered as a specific deception attack in the sense that the FDIA as the attack to the state estimator [6], MitM, FDIA, a replay attack and a deception attack [11] can be regarded as the attack of the same class.…”

“…To improve the state estimation in the presence of FDIA on measurement data, deep learning with a generative adversarial network (GAN) was also introduced [17]. Attack detector and the intermittent message authentication were proposed to improve robust control for CPS operating on the resource-constrained network in the presence of the FDIA at the measurement [18].…”