DRAUN: An Algorithm-Agnostic Data Reconstruction Attack on Federated Unlearning Systems

Fuente: arXiv
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Autores principales: Lamri, Hithem, Alam, Manaar, Jiang, Haiyan, Maniatakos, Michail
Formato: Preprint
Publicado: 2025
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author Lamri, Hithem
Alam, Manaar
Jiang, Haiyan
Maniatakos, Michail
author_facet Lamri, Hithem
Alam, Manaar
Jiang, Haiyan
Maniatakos, Michail
contents Federated Unlearning (FU) enables clients to remove the influence of specific data from a collaboratively trained shared global model, addressing regulatory requirements such as GDPR and CCPA. However, this unlearning process introduces a new privacy risk: A malicious server may exploit unlearning updates to reconstruct the data requested for removal, a form of Data Reconstruction Attack (DRA). While DRAs for machine unlearning have been studied extensively in centralized Machine Learning-as-a-Service (MLaaS) settings, their applicability to FU remains unclear due to the decentralized, client-driven nature of FU. This work presents DRAUN, the first attack framework to reconstruct unlearned data in FU systems. DRAUN targets optimization-based unlearning methods, which are widely adopted for their efficiency. We theoretically demonstrate why existing DRAs targeting machine unlearning in MLaaS fail in FU and show how DRAUN overcomes these limitations. We validate our approach through extensive experiments on four datasets and four model architectures, evaluating its performance against five popular unlearning methods, effectively demonstrating that state-of-the-art FU methods remain vulnerable to DRAs.
format Preprint
id arxiv_https___arxiv_org_abs_2506_01777
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle DRAUN: An Algorithm-Agnostic Data Reconstruction Attack on Federated Unlearning Systems
Lamri, Hithem
Alam, Manaar
Jiang, Haiyan
Maniatakos, Michail
Machine Learning
Federated Unlearning (FU) enables clients to remove the influence of specific data from a collaboratively trained shared global model, addressing regulatory requirements such as GDPR and CCPA. However, this unlearning process introduces a new privacy risk: A malicious server may exploit unlearning updates to reconstruct the data requested for removal, a form of Data Reconstruction Attack (DRA). While DRAs for machine unlearning have been studied extensively in centralized Machine Learning-as-a-Service (MLaaS) settings, their applicability to FU remains unclear due to the decentralized, client-driven nature of FU. This work presents DRAUN, the first attack framework to reconstruct unlearned data in FU systems. DRAUN targets optimization-based unlearning methods, which are widely adopted for their efficiency. We theoretically demonstrate why existing DRAs targeting machine unlearning in MLaaS fail in FU and show how DRAUN overcomes these limitations. We validate our approach through extensive experiments on four datasets and four model architectures, evaluating its performance against five popular unlearning methods, effectively demonstrating that state-of-the-art FU methods remain vulnerable to DRAs.
title DRAUN: An Algorithm-Agnostic Data Reconstruction Attack on Federated Unlearning Systems
topic Machine Learning
url https://arxiv.org/abs/2506.01777