Spatial-Temporal-Aware Graph Transformer for Transaction Fraud Detection

How to obtain informative representations of transactions and then perform the identification of fraudulent transactions is a crucial part of ensuring financial security. Recent studies apply graph neural networks (GNNs) to the transaction fraud detection problem. Nevertheless, they encounter challenges in effectively learning spatial-temporal information due to structural limitations. Moreover, few prior GNN-based detectors have recognized the significance of incorporating global information which encompasses similar behavioral patterns and offers valuable insights for discriminative representation learning. Therefore, we propose a novel heterogeneous GNN called Spatial-Temporal-Aware Graph Transformer (STA-GT) for transaction fraud detection problems. Specifically, we design a temporal encoding strategy to capture temporal dependencies and incorporate it into the GNN framework, enriching spatial-temporal information and improving expressive ability. Furthermore, we introduce a transformer module to learn local and global information. Pairwise node–node interactions overcome the limitation of the GNN structure and build up the interactions between a target node and many long-distance ones. Experimental results on two financial datasets demonstrate that our STA-GT is more effective on the transaction fraud detection task compared to general GNN models and GNN-based fraud detectors.