Adversarial Atacks on Graph Neural Networks via Node Injections: A Hierarchical Reinforcement Learning Approach Yiwei Sun Suhang Wang∗ Xianfeng Tang The Pennsylvania State University The Pennsylvania State University The Pennsylvania State University University Park, PA, USA University Park, PA, USA University Park, PA, USA
[email protected] [email protected] [email protected] Tsung-Yu Hsieh Vasant Honavar The Pennsylvania State University The Pennsylvania State University University Park, PA, USA University Park, PA, USA
[email protected] [email protected] ABSTRACT ACM Reference Format: Graph Neural Networks (GNN) ofer the powerful approach to node Yiwei Sun, Suhang Wang, Xianfeng Tang, Tsung-Yu Hsieh, and Vasant classifcation in complex networks across many domains including Honavar. 2020. Adversarial Attacks on Graph Neural Networks via Node Injections: A Hierarchical Reinforcement Learning Approach. In Proceedings social media, E-commerce, and FinTech. However, recent studies of The Web Conference 2020 (WWW ’20), April 20–24, 2020, Taipei, Taiwan. show that GNNs are vulnerable to attacks aimed at adversely im- ACM, New York, NY, USA, 11 pages. https://doi.org/10.1145/3366423.3380149 pacting their node classifcation performance. Existing studies of adversarial attacks on GNN focus primarily on manipulating the 1 INTRODUCTION connectivity between existing nodes, a task that requires greater Graphs, where nodes and their attributes denote real-world entities efort on the part of the attacker in real-world applications. In con- (e.g., individuals) and links encode relationships (e.g., friendship) trast, it is much more expedient on the part of the attacker to inject between entities, are ubiquitous in many application domains, in- adversarial nodes, e.g., fake profles with forged links, into existing cluding social media [1, 21, 35, 49, 50], e-commerce[16, 47], and graphs so as to reduce the performance of the GNN in classifying FinTech [24, 33].