Optimal Timing of Moving Target Defense: A Stackelberg Game Model

As an effective approach to thwarting advanced attacks, moving target defense (MTD) has been applied to various domains. Previous works on MTD, however, mainly focus on deciding the sequence of system configurations to be used and have largely ignored the equally important timing problem. Given that both the migration cost and attack time vary over system configurations, it is crucial to jointly optimize the spatial and temporal decisions in MTD to better protect the system from persistent threats. In this work, we propose a Stackelberg game model for MTD where the defender commits to a joint migration and timing strategy to cope with configuration-dependent migration cost and attack time distribution. The defender's problem is formulated as a semi-Markovian decision process and a nearly optimal MTD strategy is derived by exploiting the unique structure of the game.

作为一种抵御高级攻击的有效方法，移动目标防御（MTD）已应用于多个领域。然而，以往关于MTD的研究主要集中在确定要使用的系统配置序列上，在很大程度上忽略了同样重要的时间问题。鉴于迁移成本和攻击时间在不同系统配置下各不相同，在MTD中联合优化空间和时间决策以更好地保护系统免受持续性威胁至关重要。在这项工作中，我们为MTD提出了一个斯塔克尔伯格博弈模型，其中防御者采用一种联合迁移和定时策略来应对与配置相关的迁移成本和攻击时间分布。防御者的问题被表述为一个半马尔可夫决策过程，并通过利用博弈的独特结构推导出了一种近乎最优的MTD策略。