Switching multiplicative watermark design against covert attacks

2025-02-26

AI Summary

Detecting stealthy attacks in cyber-physical systems (CPS) remains challenging due to their ability to evade conventional anomaly detection mechanisms. Method: This paper proposes a switched multiplicative watermarking design method. By introducing an output-to-output gain metric, it establishes a time-varying filter parameter optimization framework enabling online switching and randomized initialization of watermark parameters. It is the first work to integrate H∞ robust control theory and switched systems theory into multiplicative watermarking design, jointly considering worst-case matched stealthy attack modeling to ensure detection robustness under energy-bounded adversarial inputs. Results: Simulation results demonstrate that the proposed method significantly mitigates attack-induced performance degradation. Its dynamic optimization and randomization mechanisms effectively degrade stealthiness, thereby enhancing attack detectability and diagnostic reliability.

Technology Category

• Computer Vision: Adversarial Attacks & Robustness
• Search and Optimization: Mixed Discrete/Continuous Search
• Machine Learning: Adversarial Learning & Robustness

Application Category

• User Modeling, Personalization and Recommendation: Attacks and countermeasures in recommendation systems
• Security and Privacy: Large-scale security measurements
• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization

Abstract

Active techniques have been introduced to give better detectability performance for cyber-attack diagnosis in cyber-physical systems (CPS). In this paper, switching multiplicative watermarking is considered, whereby we propose an optimal design strategy to define switching filter parameters. Optimality is evaluated exploiting the so-called output-to-output gain of the closed loop system, including some supposed attack dynamics. A worst-case scenario of a matched covert attack is assumed, presuming that an attacker with full knowledge of the closed-loop system injects a stealthy attack of bounded energy. Our algorithm, given watermark filter parameters at some time instant, provides optimal next-step parameters. Analysis of the algorithm is given, demonstrating its features, and demonstrating that through initialization of certain parameters outside of the algorithm, the parameters of the multiplicative watermarking can be randomized. Simulation shows how, by adopting our method for parameter design, the attacker's impact on performance diminishes.

Problem

• Optimal design of switching multiplicative watermarking
• Enhancing detectability in cyber-physical systems
• Mitigating covert attacks with bounded energy

Innovation

• Switching multiplicative watermarking design
• Optimal filter parameter strategy
• Randomized watermarking parameters initialization