Mangling Rules Generation With Density-Based Clustering for Password Guessing

Rule-based password generation is one of the most effective and often employed techniques in the highly compute-intensive password recovery process. However, it is challenging to design and maintain a practical password mangling ruleset, which is a time-consuming task requiring specialized expertise. This paper therefore introduced MDBSCAN (Modified Density-Based Spatial Clustering of Applications with Noise), a novel density-based cluster approach in machine learning, to build an automatic password mangling rule generator. To evaluate the proposed method, cross-checks across 4 different real-world password datasets leaked from popular Internet services and applications are adopted. The results indicate that the proposed generator could produce high-quality mangling rules with a better hit rate and enhance current mangling rules by identifying hidden or omitted rules. The proposed approach also shows strong interpretability and computational efficiency. When examining the RockYou password dataset with the top 77 rules, the hit rate may rise by 11% to 104% proportionally to other well-known solutions. Furthermore, by combining the top 77 rules generated by MDBSCAN with those from other rulesets, 3–12.67% more real-world passwords can be retrieved.