FedPhishLLM: A privacy-preserving and explainable phishing detection mechanism using federated learning and LLMs
摘要
Phishing attacks remain a significant cybersecurity threat, exploiting social engineering techniques to deceive users and steal sensitive information. Traditional phishing detection mechanisms based on machine learning and deep learning often rely on centralized data collection, raising privacy concerns and limiting adaptability to diverse user environments. Recent advancements in large language models (LLMs) have introduced new opportunities for phishing detection by leveraging multimodal data, yet existing approaches primarily depend on commercial LLMs, which increase operational costs and potentially compromise user privacy. To address these challenges, we propose FedPhishLLM, a privacy-preserving and explainable phishing detection framework that integrates federated learning (FL) with fine-tuned multimodal LLMs. Our approach enables decentralized model training, allowing users to collaboratively improve phishing detection without sharing raw data, thereby preserving privacy while maintaining high detection accuracy. FedPhishLLM enhances explainability by providing phishing explanations, including brand identification and intent recognition, fostering user trust and informed decision-making. Experimental results confirm that our framework outperforms all baseline models, achieving up to 95% accuracy, precision, and F1-score with 96% recall. Further analyses validate the rationality of chosen training parameters and prompting strategies, demonstrate the complementary value of multimodal phishing indicators, and highlight the framework’s adaptability to linguistic heterogeneity as well as resilience against adversarial and evasive attacks. To the best of our knowledge, FedPhishLLM is one of the first FL-based multimodal LLM approaches for phishing detection, offering a scalable, privacy-conscious, and explainable security solution practical for real-world deployments.