Semantic Clustering of Obfuscated Command-Line Detections for Alert Reduction

Barbora Štěpánková, Vojtěch Outrata, Martin Kopp


Abstract
We propose a post-processing method for grouping large volumes of command-line detections into semantically coherent cluster-level alerts. The approach combines embedding-based clustering with LLM-based cluster-level filtering: command-lines are first encoded using Sentence-BERT embeddings and grouped via hierarchical agglomerative clustering, after which a large language model evaluates cluster representatives to reduce the number of false positive alerts. We evaluate the method on real-world telemetry from a commercial endpoint protection system, applying it to detections produced by an obfuscation detection model. On one week of data, the pipeline reduces alert volume by approximately 98% while maintaining high cluster purity and semantic coherence, demonstrating its effectiveness as a scalable post-processing step in high-volume detection settings.
Anthology ID:
2026.nlpaics-1.19
Volume:
Proceedings of the Second International Conference on Natural Language Processing and Artificial Intelligence for Cyber Security
Month:
June
Year:
2026
Address:
Alicante, Spain
Editors:
Ruslan Mitkov, Rafael Muñoz, Elena Lloret, Tharindu Ranasinghe, Ernesto L. Estevanell-Valladares, Salima Lamsiyah, Andrés Montoyo, Saad Ezzini
Venue:
NLPAICS
SIG:
Publisher:
Department of Languages and Information Systems, University of Alicante
Note:
Pages:
176–183
Language:
URL:
https://aclanthology.org/2026.nlpaics-1.19/
DOI:
Bibkey:
Cite (ACL):
Barbora Štěpánková, Vojtěch Outrata, and Martin Kopp. 2026. Semantic Clustering of Obfuscated Command-Line Detections for Alert Reduction. In Proceedings of the Second International Conference on Natural Language Processing and Artificial Intelligence for Cyber Security, pages 176–183, Alicante, Spain. Department of Languages and Information Systems, University of Alicante.
Cite (Informal):
Semantic Clustering of Obfuscated Command-Line Detections for Alert Reduction (Štěpánková et al., NLPAICS 2026)
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PDF:
https://aclanthology.org/2026.nlpaics-1.19.pdf