ShellForge: Adversarial Co-Evolution of Webshell Generation and Multi-View Detection for Robust Webshell Defense
This work addresses the challenge that existing webshell detection methods struggle to keep pace with rapidly evolving obfuscated variants and suffer from high false-positive rates on benign obfuscated scripts. To overcome these limitations, the authors propose an adversarial co-evolution framework in which a generator and a multi-perspective detector iteratively train each other to continuously enhance defensive capabilities. The approach innovatively leverages de-maliciousized samples as high-quality hard negatives and integrates supervised fine-tuning with preference-based reinforcement learning to generate highly evasive webshells. The detector combines multi-view features, including semantic compression of long strings, pruned abstract syntax tree (AST) structures, and Shannon entropy. Evaluated on the FWOID benchmark, the method achieves an F1-score of 0.981, and its generated samples attain a 0.939 evasion success rate against commercial VirusTotal engines, significantly reducing false positives while improving generalization.