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Abstract

Open source software (OSS) has become the foundation of modern applications, but its transitive dependencies make it especially vulnerable to supply chain attacks. One common tactic is to inject malicious code into third-party packages. NPM, in particular, due to its widespread use and large volume of packages, has become a popular target of malicious code injection. While various detectors have been proposed, they suffer from four limitations, i.e., inadequate behavior modeling of obfuscated code, ignoring object-centric features of JavaScript, lack of synergy between static and dynamic analysis, and semantic information loss in behavior abstraction as well as a lack of interpretability in detection results. These limitations lead to imprecise modeling of program behavior and hinder detection effectiveness. To address these limitations, we propose ProfMalPlus, a malicious NPM package detector that combines behavior graph analysis with coordinated LLM-based reasoning over annotated code slices.