Extracting Attack Pattern From WAF Logs and CTIs Using Contrastive Semantic Learning

Abstract

Web Application Firewalls (WAFs) are widely deployed to protect web services, but their rule-based design provides limited visibility into attacker intent. WAF logs consist primarily of low-level HTTP artifacts that lack the behavioral context required for effective threat analysis. To address this limitation, we propose the first automated framework that maps WAF logs to MITRE ATT&CK techniques through CTI-grounded semantic learning. The approach integrates structure-aware Monte Carlo Tree Search-based payload generation, CodeBERT-driven contrastive learning for attack classification, and cyber threat intelligence (CTI) alignment for TTP retrieval. The framework is evaluated on over 714,000 WAF logs derived from validated attack payloads across eight attack types, generated within a controlled environment using ModSecurity and OWASP Core Rule Set (CRS). Experimental results demonstrate 99.38% multi-class classification F1 score and identification of 206 unique ATT&CK techniques. Compared with a Rule-ID Heuristic baseline derived from OWASP CRS rule semantics, the proposed framework identifies $7.4\times $ more unique ATT&CK techniques and provides substantially broader TTP-level visibility. External validation on a real-world ModSecurity log dataset further demonstrates that the framework preserves reliable classification and retrieval performance beyond the controlled payload-generation setting.