Intriguing Properties of Adversarial Examples

Barret Zoph
Sam Schoenholz
ICLR (2018)

Abstract

It is becoming increasingly clear that many machine learning classifiers are vulnerable
to adversarial examples. In attempting to explain the origin of adversarial
examples, previous studies have typically focused on the fact that neural networks
operate on high dimensional data, they overfit, or they are too linear. Here we
argue that the origin of adversarial examples is primarily due to an inherent uncertainty
that neural networks have about their predictions. We show that the functional
form of this uncertainty is independent of architecture, dataset, and training
protocol; and depends only on the statistics of the logit differences of the network,
which do not change significantly during training. This leads to adversarial error
having a universal scaling, as a power-law, with respect to the size of the adversarial
perturbation. We show that this universality holds for a broad range of datasets
(MNIST, CIFAR10, ImageNet, and random data), models (including state-of-theart
deep networks, linear models, adversarially trained networks, and networks
trained on randomly shuffled labels), and attacks (FGSM, step l.l., PGD). Motivated
by these results, we study the effects of reducing prediction entropy on
adversarial robustness. Finally, we study the effect of network architectures on
adversarial sensitivity. To do this, we use neural architecture search with reinforcement
learning to find adversarially robust architectures on CIFAR10. Our
resulting architecture is more robust to white and black box attacks compared to
previous attempts.