Neural networks are vulnerable to adversarial attacks -small visually imperceptible crafted noise which when added to the input drastically changes the output. The most effective method of defending against adversarial attacks is to use the methodology of adversarial training. We analyze the adversarially trained robust models to study their vulnerability against adversarial attacks at the level of the latent layers. Our analysis reveals that contrary to the input layer which is robust to adversarial attack, the latent layer of these robust models are highly susceptible to adversarial perturbations of small magnitude. Leveraging this information, we introduce a new technique Latent Adversarial Training (LAT) which comprises of finetuning the adversarially trained models to ensure the robustness at the feature layers. We also propose Latent Attack (LA), a novel algorithm for constructing adversarial examples. LAT results in a minor improvement in test accuracy and leads to a state-of-the-art adversarial accuracy against the universal first-order adversarial PGD attack which is shown for the MNIST, CIFAR-10, CIFAR-100, SVHN and Restricted ImageNet datasets.
REF observes that latent layers of an adversarially trained model is not robust and proposed a technique to perform adversarial training of latent layer (termed as LAT) in conjunction with adversarial training of the full network which aims at increasing the adversarial robustness of the model.
Harnessing the Vulnerability of Latent Layers in Adversarially Trained Models
IJCAI
Computer Science Mathematics