## 6 Issues and Challenges in the Defense Against Deliberate Attacks on IECPS
### Obstacles in Defense Evaluation and Improvement  
Scinentifically and reasonably evaluating the system's ability to resist deliberate attacks is fundamental to enhancing the defense capability of IECPS. It offers quantifiable standards for system design, operation and maintenance management, as well as the formulation of efficient defense strategies. However, most current defense evaluation methods use the reduction in system losses as the evaluation criterion for the enhancement of defense capability. While these methods can accurately depict the defense capability of a single energy system, the complex coupled dynamics of IECPS cannot be accurately captured by the reduction in system losses when the defense capability of IECPS is being assessed.  
Firstly, there are significant dynamic characteristic differences between various energy systems, and their losses manifest differently in terms of time and space. For example, the response speed of the power system is typically within seconds or even milliseconds, whereas thermal and gas systems undergo dynamic changes typically on a scale of minutes. This dynamic difference results in asynchronous responses and recovery processes among different energy subsystems when implementing defense measures and facing attacks, making the accurate quantification of the impacts of these disturbance events highly complex at the physical layer.  
The high coupling between the IECPS cyber network and the physical network further increases the complexity of the evaluation. The disruption of the cyber system affects the system's perception and control capabilities, subsequently impacting the operation of the physical system through the cyber-physical coupling mechanism. Existing evaluation methods often overlook the impact of cyber system losses on the overall system; instead, they use the losses in the physical system as the evaluation criterion for the entire system, leading to significant discrepancies in the evaluation results.  
In addition, the stealth and unpredictability of deliberate attacks further complicate defense evaluation. In actual defense processes, there is often a scarcity of sufficient and complete attack event data, prompting the use of simulations based on hypothetical attack scenarios. These hypothetical defense enhancement strategies can theoretically offer effective evaluation methods and improvement strategies for system defense, but validating them in real experimental environments proves challenging, thereby limiting the development of defense evaluation and enhancement technologies.  
The obstacles in defense evaluation and improvement are integral to the entire process of formulating defense strategies. First, all defense strategies involving modeling cannot be separated from evaluation. Evaluation is not merely a process of validating results; it directly determines the effectiveness and optimization direction of defense strategies. Evaluation metrics typically represent the goals of defense optimization, and they must be scientific and rational. If unscientific evaluation metrics or methods are used, the resulting defense strategies may fail to meet the system's security requirements in practice and may even lead to unnecessary resource wastage. Furthermore, when evaluating the superiority of detection methods, multiple comprehensive indicators are typically required. For example, in attack detection methods, it is important not only to consider detection accuracy but also to account for detection speed, false positive rates, false negative rates, and other performance dimensions. The trade-offs and choices between these metrics are also part of defense evaluation. Therefore, defense evaluation is not just a summary of the results of defense strategies, but also an important basis for strategy improvement and adjustment.