ISADM: An Integrated STRIDE, ATT&CK, and D3FEND Model for Threat Modeling Against Real-world Adversaries

FinTechs increasing connectivity, rapid innovation, and reliance on global digital infrastructures present significant cybersecurity challenges. Traditional cybersecurity frameworks often struggle to identify and prioritize sector-specific vulnerabilities or adapt to evolving adversary tactics, particularly in highly targeted sectors such as FinTech. To address these gaps, we propose ISADM (Integrated STRIDE-ATTACK-D3FEND Threat Model), a novel hybrid methodology applied to FinTech security that integrates STRIDE's asset-centric threat classification with MITRE ATTACK's catalog of real-world adversary behaviors and D3FEND's structured knowledge of countermeasures. ISADM employs a frequency-based scoring mechanism to quantify the prevalence of adversarial Tactics, Techniques, and Procedures (TTPs), enabling a proactive, score-driven risk assessment and prioritization framework. This proactive approach contributes to shifting organizations from reactive defense strategies toward the strategic fortification of critical assets. We validate ISADM through industry-relevant case study analyses, demonstrating how the approach replicates actual attack patterns and strengthens proactive threat modeling, guiding risk prioritization and resource allocation to the most critical vulnerabilities. Overall, ISADM offers a comprehensive hybrid threat modeling methodology that bridges asset-centric and adversary-centric analysis, providing FinTech systems with stronger defenses. The emphasis on real-world validation highlights its practical significance in enhancing the sector's cybersecurity posture through a frequency-informed, impact-aware prioritization scheme that combines empirical attacker data with contextual risk analysis.