LogST: Log Semi-supervised Anomaly Detection Based on Sentence-BERT

Semantics extraction is a very important part in the field of log anomaly detection, how to accurately obtain the semantics representation of log events will have a direct impact on the final anomaly detection results. However, existing research focuses on using word embedding to extract the semantics of log events, this method based on weighted aggregation of all word vectors may lose the semantic relationship of word order, and does not consider the interaction between words in log events, which cannot fully represent the semantics of log events. To solve this problem and further improve the anomaly detection performance, this paper proposes a novel practical log-based anomaly detection approach, LogST, which uses the SBERT model to extract the semantics representation of log events, considering the semantic and word order relationship of each word of log events, which is convenient to understand the log sequence context, and then design a GRU model for anomaly detection. Experimental results conducted on the public HDFS datasets demonstrate that LogST outperforms other methods in the case of a sufficient number of labeled normal logs, and can still guarantee the stability of anomaly detection accuracy in the case of a small number of labeled normal logs.