2017/10/30 by Yang Song, Taesup Kim, Song, Yang +7 · 294 citations
Biochemistry, Genetics and Molecular Biology · Computer Science · #Advanced Malware Detection Techniques #Adversarial Robustness in Machine Learning #Adversarial system #Anomaly Detection Techniques and Applications #Artificial intelligence #Artificial neural network #Bacillus and Francisella bacterial research #Classifier (UML) #Computer science #Contextual image classification #FOS: Computer and information sciences #Generative grammar #Generative model #Image (mathematics) #MNIST database #Machine Learning (cs.LG) #Machine learning #Pattern recognition (psychology) #Security and Verification in Computing #cs.LG
paper · pdf · doi:10.48550/arxiv.1710.10766
published in arXiv (Cornell University) (Cornell University) · ICLR 2018
openalex publication_date 2017/10/30 · arxiv created 2018/05/21 · arxiv updated 2018/05/22 · openalex created_date 2019/07/30 · openalex updated_date 2026/08/05
Adversarial perturbations of normal images are usually imperceptible to humans, but they can seriously confuse state-of-the-art machine learning models. What makes them so special in the eyes of image classifiers? In this paper, we show empirically that adversarial examples mainly lie in the low probability regions of the training distribution, regardless of attack types and targeted models. Using statistical hypothesis testing, we find that modern neural density models are surprisingly good at detecting imperceptible image perturbations. Based on this discovery, we devised PixelDefend, a new approach that purifies a maliciously perturbed image by moving it back towards the distribution seen in the training data. The purified image is then run through an unmodified classifier, making our method agnostic to both the classifier and the attacking method. As a result, PixelDefend can be used to protect already deployed models and be combined with other model-specific defenses. Experiments show that our method greatly improves resilience across a wide variety of state-of-the-art attacking methods, increasing accuracy on the strongest attack from 63% to 84% for Fashion MNIST and from 32% to 70% for CIFAR-10.