Poisoning Attacks and Defenses to Federated Unlearning

Fuente: arXiv
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Main Authors: Wang, Wenbin, Ma, Qiwen, Zhang, Zifan, Liu, Yuchen, Liu, Zhuqing, Fang, Minghong
Format: Preprint
Published: 2025
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_version_ 1866910803482902528
author Wang, Wenbin
Ma, Qiwen
Zhang, Zifan
Liu, Yuchen
Liu, Zhuqing
Fang, Minghong
author_facet Wang, Wenbin
Ma, Qiwen
Zhang, Zifan
Liu, Yuchen
Liu, Zhuqing
Fang, Minghong
contents Federated learning allows multiple clients to collaboratively train a global model with the assistance of a server. However, its distributed nature makes it susceptible to poisoning attacks, where malicious clients can compromise the global model by sending harmful local model updates to the server. To unlearn an accurate global model from a poisoned one after identifying malicious clients, federated unlearning has been introduced. Yet, current research on federated unlearning has primarily concentrated on its effectiveness and efficiency, overlooking the security challenges it presents. In this work, we bridge the gap via proposing BadUnlearn, the first poisoning attacks targeting federated unlearning. In BadUnlearn, malicious clients send specifically designed local model updates to the server during the unlearning process, aiming to ensure that the resulting unlearned model remains poisoned. To mitigate these threats, we propose UnlearnGuard, a robust federated unlearning framework that is provably robust against both existing poisoning attacks and our BadUnlearn. The core concept of UnlearnGuard is for the server to estimate the clients' local model updates during the unlearning process and employ a filtering strategy to verify the accuracy of these estimations. Theoretically, we prove that the model unlearned through UnlearnGuard closely resembles one obtained by train-from-scratch. Empirically, we show that BadUnlearn can effectively corrupt existing federated unlearning methods, while UnlearnGuard remains secure against poisoning attacks.
format Preprint
id arxiv_https___arxiv_org_abs_2501_17396
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Poisoning Attacks and Defenses to Federated Unlearning
Wang, Wenbin
Ma, Qiwen
Zhang, Zifan
Liu, Yuchen
Liu, Zhuqing
Fang, Minghong
Cryptography and Security
Distributed, Parallel, and Cluster Computing
Machine Learning
Federated learning allows multiple clients to collaboratively train a global model with the assistance of a server. However, its distributed nature makes it susceptible to poisoning attacks, where malicious clients can compromise the global model by sending harmful local model updates to the server. To unlearn an accurate global model from a poisoned one after identifying malicious clients, federated unlearning has been introduced. Yet, current research on federated unlearning has primarily concentrated on its effectiveness and efficiency, overlooking the security challenges it presents. In this work, we bridge the gap via proposing BadUnlearn, the first poisoning attacks targeting federated unlearning. In BadUnlearn, malicious clients send specifically designed local model updates to the server during the unlearning process, aiming to ensure that the resulting unlearned model remains poisoned. To mitigate these threats, we propose UnlearnGuard, a robust federated unlearning framework that is provably robust against both existing poisoning attacks and our BadUnlearn. The core concept of UnlearnGuard is for the server to estimate the clients' local model updates during the unlearning process and employ a filtering strategy to verify the accuracy of these estimations. Theoretically, we prove that the model unlearned through UnlearnGuard closely resembles one obtained by train-from-scratch. Empirically, we show that BadUnlearn can effectively corrupt existing federated unlearning methods, while UnlearnGuard remains secure against poisoning attacks.
title Poisoning Attacks and Defenses to Federated Unlearning
topic Cryptography and Security
Distributed, Parallel, and Cluster Computing
Machine Learning
url https://arxiv.org/abs/2501.17396