GRAAL: GRAph-based Analysis of Logs for Advanced AI-based Intrusion Detection Systems
Intrusion Detection Systems (IDS) are essential tools for detecting and analyzing malicious system activity. Anomaly-based IDS have gained popularity due to their ability to detect zero-day attacks, unlike signature-based IDS. Although this approach is promising, recent AI-based IDS still suffer from high false positive rates, non-scalability and biases, which limit their practicality in real-world deployments.This paper presents GRAAL, an end-to-end unsupervised graph-based anomaly-based IDS that allows a scalable multi-level detection, achieves a low false positive rate, and provides intuitive and interpretable outputs to assist analysts in threat detection and investigation. GRAAL proposes a method to extract features from heterogeneous provenance graphs, using a combination of structural and attribute embeddings. These vectors are then processed by multiple autoencoder models to detect anomalies at both graph and system entity levels. GRAAL’s models leverage the relationship between the graph and entity levels, sharing knowledge through transfer learning and combining their results. We compare GRAAL against six state-of-the-art IDS on several datasets. These comparisons reveal methodological and reproducible biases in the evaluation of the current IDS and lead us to define best practices. To perform a comprehensive comparison, we mitigate biases still present in these state-of-the-art IDS. These extensive evaluations of GRAAL show that GRAAL outperforms these IDS, with a higher precision.