Hybrid VAE-Transformer-based multi-task learning for cyberattack detection and fault classification in electric...

Electric vehicle (EV) charging stations have become a complex cyber-physical system, where the sensor network is susceptible to both hardware failures and cyberattacks. Both produce similar data patterns, making them difficult to distinguish. The majority of the approaches have addressed only cyberattacks or faults and rely on recurrent architectures, which are hard to capture long-term temporal patterns. In this study, a multi-task learning framework for cyberattack detection and fault classification is proposed based on four hybrid deep learning models, namely Variational Autoencoder-Long Short-Term Memory (VAE-LSTM), VAE-Gated Recurrent Unit (VAE-GRU), VAE-Generative Adversarial Network (VAE-GAN), and VAE-Transformer. The framework is tested on a publicly available EV Internet of Things (IoT) predictive-maintenance dataset with six threat scenarios like Fast Gradient Sign Method (FGSM), Projected Gradient Descent (PGD), Replay attacks, Man-in-the-Middle (MitM) attacks, Message Manipulation attacks, and a Flatline sensor fault. The results show that the VAE-Transformer achieved an Area Under the Curve-Receiver Operating Characteristic (AUC-ROC) of 99.76%, a binary F1-score of 99.03%, an attack-type Macro-F1 of 97.29%, an FPR@95% of 0.41%, and a Matthews correlation coefficient (MCC) of 98.20%. Furthermore, the low values of orthogonality and Mutual Information (MI) loss demonstrate that the proposed hybrid deep learning algorithm successfully separates cyberattack and physical fault features, thereby improving overall detection performance.