Netinfo Security ›› 2026, Vol. 26 ›› Issue (5): 684-698.doi: 10.3969/j.issn.1671-1122.2026.05.002

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A Training-Free Black-Box Attack against DeepFake Detectors via Frequency Distribution Alignment

YU Chuer1, WANG Hanyue1, WU Jian2,3,4, DING Weijie3, CHEN Xianqian2,4, WANG Zonghui1()   

  1. 1 College of Computer Science and Technology, Zhejiang University, Hangzhou 310027, China
    2 Cybersecurity Corps, Zhejiang Provincial Public Security Department, Hangzhou 310009, China
    3 College of Information and Cyber Security, Zhejiang Police College, Hangzhou 310053, China
    4 School of Cyber Science and Technology, Zhejiang University, Hangzhou 310027, China
  • Received:2026-01-20 Online:2026-05-10 Published:2026-06-03

Abstract:

As deepfake generation quality increasingly approaches that of real images, deepfake detection has become crucial for multimedia content security. However, most existing methods rely on statistical discrepancies between real and fake samples, rendering them potentially vulnerable under black-box conditions. This paper investigated the security of deepfake detection systems in a training-free, zero-query black-box setting and introduced a novel attack perspective: modeling adversarial attacks as targeted correction of statistical fingerprints in fake images, rather than exogenous noise perturbations. Based on this insight, this paper proposed SpectralFusion, a training-free black-box method that aligns frequency-domain distribution distributions. Leveraging the inherent real-fake paired prior present in deepfake generation, SepctralFusion identifies statistical discrepancies between fake images and their real references through frequency-domain analysis and applies controlled corrections only to anomalous frequency bands—without accessing model parameters, gradients, or additional training and queries. Specifically, we designed a difference-aware frequency band mask to accurately localize abnormal frequency components, and introduced an adaptive fusion strength mechanism to dynamically regulate correction intensity. Combined with a local overlapping block-based frequency processing strategy, our method enables fine-grained alignment and reconstruction of manipulated frequency features. Extensive experiments results show that SpectralFusion consistently deceives multiple deepfake detection models while preserving high visual fidelity, and generalizes well across diverse model architectures and manipulation types. Our findings reveal inherent vulnerabilities of deepfake detectors in the frequency-domain statistical space, offering a new perspective for evaluating the robustness of black-box detection systems in real-world scenarios.

Key words: deepfake detection, black-box attack, frequency distribution alignment

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