LEXIDNS-RISK: DEPLOYMENT-AWARE LEXICAL RISK MODELING FOR INTERPRETABLE MALICIOUS DOMAIN SCREENING
DOI:
https://doi.org/10.71146/kjmr904Keywords:
Malicious Domain Detection, DNS-layer screening, Lexical Feature Modeling, Interpretable Machine Learning, Robustness-Aware CybersecurityAbstract
Malicious domains are widely used in phishing, malware delivery, command-and-control communication, and DNS-based abuse. This paper evaluates lightweight lexical-feature-based models for first-stage DNS-layer malicious-domain screening. Using a balanced dataset of two million labeled domains, we extract interpretable features from domain strings and compare Logistic Regression, Random Forest, Extra Trees, XGBoost, LightGBM, and a character n-gram TF-IDF baseline. Results show that lexical boosting models achieve strong clean-test performance. LightGBM obtains the best F1-score of approximately 0.997, while XGBoost provides nearly identical accuracy with lower latency and smaller model size. Compared with the TF-IDF baseline, lexical boosting models achieve higher F1-score, lower false-positive rate, and lower inference cost. Feature-importance analysis shows that base-domain length, digit ratio, digit count, token length, and character diversity are the dominant signals. Robustness experiments show that clean-test accuracy alone is insufficient for deployment-oriented evaluation, as several domain perturbations reduce fixed-threshold performance. Threshold recalibration improves some stress cases, but subdomain-noise remains challenging. Overall, lightweight lexical models can support fast and interpretable first-stage DNS-layer screening under controlled evaluation, but external validation and robustness-aware modeling are required before stronger deployment claims can be made.
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Copyright (c) 2026 Wahaj Hassan Soomro, Muhammad Arslan Siddiqui (Author)

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