Imbalanced Gradients: A Subtle Cause of Overestimated Adversarial Robustness. (arXiv:2006.13726v4 [cs.CV] UPDATED)

Evaluating the robustness of a defense model is a challenging task in
adversarial robustness research. Obfuscated gradients have previously been
found to exist in many defense methods and cause a false signal of robustness.
In this paper, we identify a more subtle situation called Imbalanced Gradients
that can also cause overestimated adversarial robustness. The phenomenon of
imbalanced gradients occurs when the gradient of one term of the margin loss
dominates and pushes the attack towards to a suboptimal direction. To …

adversarial attack called defense exploit identify loss obfuscated research robustness signal task