Adversarial Robustness with Non-uniform Perturbations

Robustness of machine learning models is critical for security related applications, where real-world adversaries are uniquely focused on evading neural network based detectors. Prior work mainly focus on crafting adversarial examples with small uniform norm-bounded perturbations across features to maintain the requirement of imperceptibility. Although such approaches are valid for images, uniform perturbations do not result in realistic adversarial examples in domains such as malware, finance, and social networks. For these types of applications, features typically have some semantically meaningful dependencies. The key idea of our proposed approach is to enable non-uniform perturbations that can adequately represent these feature dependencies during adversarial training. We propose using characteristics of the empirical data distribution, both on correlations between the features and the importance of the features themselves. Using experimental datasets for malware classification, credit risk prediction, and spam detection, we show that our approach is more robust to real-world attacks. Our approach can be adapted to other domains where non-uniform perturbations more accurately represent realistic adversarial examples.