Hardening Machine Learning based Network Intrusion Detection Systems with Synthetic NetFlows

Modern Network Intrusion Detection Systems (NIDS) involve Machine Learning (ML) algorithms to automate the detection process. Although this integration has significantly enhanced their efficiency, ML models have been found vulnerable to adversarial attacks, which alter the input data to fool the detectors into producing a misclassification. Among the proposed countermeasures, adversarial training appears to be the most promising technique; however, it demands a large number of adversarial samples, which typically have to be manually produced. We overcome this limitation by introducing a novel methodology that employs a Graph AutoEncoder (GAE) to generate synthetic traffic records automatically. By design, the generated samples exhibit alterations in the attributes compared to the original netflows, making them suitable for use as adversarial samples during the adversarial training procedure. By injecting the generated samples into the training set, we obtain hardened detectors with better resilience to adversarial attacks. Our experimental campaign based on a public dataset of real enterprise network traffic also demonstrates that the proposed method even improves the detection rates of the hardened detectors in non-adversarial settings.