LogGAN: a Log-level Generative Adversarial Network for Anomaly Detection using Permutation Event Modeling

System logs that trace system states and record valuable events comprise a significant component of any computer system in our daily life. Each log contains sufficient information (i.e., normal and abnormal instances) that assist administrators in diagnosing and maintaining the operation of systems. If administrators cannot detect and eliminate diverse and complex anomalies (i.e., bugs and failures) efficiently, running workflows and transactions, even systems, would break down. Therefore, the technique of anomaly detection has become increasingly significant and attracted a lot of research attention. However, current approaches concentrate on the anomaly detection analyzing a high-level granularity of logs (i.e., session) instead of detecting log-level anomalies which weakens the efficiency of responding anomalies and the diagnosis of system failures. To overcome the limitation, we propose an LSTM-based generative adversarial network for anomaly detection based on system logs using permutation event modeling named LogGAN, which detects log-level anomalies based on patterns (i.e., combinations of latest logs). On the one hand, the permutation event modeling mitigates the strong sequential characteristics of LSTM for solving the out-of-order problem caused by the arrival delays of logs. On the other hand, the generative adversarial network-based model mitigates the impact of imbalance between normal and abnormal instances to improve the performance of detecting anomalies. To evaluate LogGAN, we conduct extensive experiments on two real-world datasets, and the experimental results show the effectiveness of our proposed approach on the task of log-level anomaly detection.