SpaNN: Detecting Multiple Adversarial Patches on CNNs by Spanning Saliency Thresholds

Fuente: arXiv
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Auteurs principaux: Victorica, Mauricio Byrd, Dán, György, Sandberg, Henrik
Format: Preprint
Publié: 2025
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author Victorica, Mauricio Byrd
Dán, György
Sandberg, Henrik
author_facet Victorica, Mauricio Byrd
Dán, György
Sandberg, Henrik
contents State-of-the-art convolutional neural network models for object detection and image classification are vulnerable to physically realizable adversarial perturbations, such as patch attacks. Existing defenses have focused, implicitly or explicitly, on single-patch attacks, leaving their sensitivity to the number of patches as an open question or rendering them computationally infeasible or inefficient against attacks consisting of multiple patches in the worst cases. In this work, we propose SpaNN, an attack detector whose computational complexity is independent of the expected number of adversarial patches. The key novelty of the proposed detector is that it builds an ensemble of binarized feature maps by applying a set of saliency thresholds to the neural activations of the first convolutional layer of the victim model. It then performs clustering on the ensemble and uses the cluster features as the input to a classifier for attack detection. Contrary to existing detectors, SpaNN does not rely on a fixed saliency threshold for identifying adversarial regions, which makes it robust against white box adversarial attacks. We evaluate SpaNN on four widely used data sets for object detection and classification, and our results show that SpaNN outperforms state-of-the-art defenses by up to 11 and 27 percentage points in the case of object detection and the case of image classification, respectively. Our code is available at https://github.com/gerkbyrd/SpaNN.
format Preprint
id arxiv_https___arxiv_org_abs_2506_18591
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle SpaNN: Detecting Multiple Adversarial Patches on CNNs by Spanning Saliency Thresholds
Victorica, Mauricio Byrd
Dán, György
Sandberg, Henrik
Computer Vision and Pattern Recognition
Machine Learning
State-of-the-art convolutional neural network models for object detection and image classification are vulnerable to physically realizable adversarial perturbations, such as patch attacks. Existing defenses have focused, implicitly or explicitly, on single-patch attacks, leaving their sensitivity to the number of patches as an open question or rendering them computationally infeasible or inefficient against attacks consisting of multiple patches in the worst cases. In this work, we propose SpaNN, an attack detector whose computational complexity is independent of the expected number of adversarial patches. The key novelty of the proposed detector is that it builds an ensemble of binarized feature maps by applying a set of saliency thresholds to the neural activations of the first convolutional layer of the victim model. It then performs clustering on the ensemble and uses the cluster features as the input to a classifier for attack detection. Contrary to existing detectors, SpaNN does not rely on a fixed saliency threshold for identifying adversarial regions, which makes it robust against white box adversarial attacks. We evaluate SpaNN on four widely used data sets for object detection and classification, and our results show that SpaNN outperforms state-of-the-art defenses by up to 11 and 27 percentage points in the case of object detection and the case of image classification, respectively. Our code is available at https://github.com/gerkbyrd/SpaNN.
title SpaNN: Detecting Multiple Adversarial Patches on CNNs by Spanning Saliency Thresholds
topic Computer Vision and Pattern Recognition
Machine Learning
url https://arxiv.org/abs/2506.18591