A Defense Framework for Backdoor Attacks in Federated Learning Based on Client-Server Detection

Addressing the challenge of backdoor attacks in federated learning (FL), various defense schemes are examined, resulting in the proposal of a comprehensive strategy that incorporates both client-side and server-side measures. This defense strategy is based on Dropout and LOF (Local Outlier Factor) outlier detection techniques. The model's resilience against data poisoning is enhanced by applying the Dropout technique on the client side. At the same time, the LOF outlier detection algorithm is utilized on the server side to identify potential abnormal model updates. Experimental results highlight the effectiveness of the proposed strategy, demonstrating a significant reduction in the Attack Success Rate (ASR) from 88.11% to 1.62% on the FMNIST dataset, and from 95.45% to only 0.25% on the EMNIST dataset. The success rate of backdoor attacks is notably diminished, confirming the strategy's strong backdoor defense capabilities.