Stackelberg Security Games with Contagious Attacks on a Network: Reallocation to the Rescue

• Published in: The Journal of artificial intelligence research Vol. 77; pp. 487 - 515
• Main Authors: Bai, Rufan, Lin, Haoxing, Yang, Xinyu, Wu, Xiaowei, Li, Minming, Jia, Weijia
• Format: Journal Article
• Language: English
• Published: 01.01.2023
• ISSN: 1076-9757; 1943-5037; 1076-9757
• DOI: 10.1613/jair.1.14563

In the classic network security games, the defender distributes defending resources to the nodes of the network, and the attacker attacks a node, with the objective of maximizing the damage caused. In this paper, we consider the network defending problem against contagious attacks, e.g., the attack at a node u spreads to the neighbors of u and can cause damage at multiple nodes. Existing works that study shared resources assume that the resource allocated to a node can be shared or duplicated between neighboring nodes. However, in the real world, sharing resource naturally leads to a decrease in defending power of the source node, especially when defending against contagious attacks. Therefore, we study the model in which resources allocated to a node can only be transferred to its neighboring nodes, which we refer to as a reallocation process. We show that the problem of computing optimal defending strategy is NP-hard even for some very special cases. For positive results, we give a mixed integer linear program formulation for the problem and a bi-criteria approximation algorithm. Our experimental results demonstrate that the allocation and reallocation strategies our algorithm computes perform well in terms of minimizing the damage due to contagious attacks.