Decision Guided Robust DL Classification of Adversarial Images Combining Weaker Defenses

Adversarial examples make Deep Learning (DL) models vulnerable to safe deployment in practical systems. Although several techniques have been proposed in the literature, defending against adversarial attacks is still challenging. The current work identifies weaknesses of traditional strategies in detecting and classifying adversarial examples. To overcome these limitations, we carefully analyze techniques like binary detector and ensemble method, and compose them in a manner which mitigates the limitations. We also effectively develop a re-attack strategy, a randomization technique called RRP (Random Resizing and Patch-removing), and a rule-based decision method. Our proposed method, BEARR (Binary detector with Ensemble and re-Attacking scheme including Randomization and Rule-based decision technique) detects adversarial examples as well as classifies those examples with a higher accuracy compared to contemporary methods. We evaluate BEARR on standard image classification datasets: CIFAR-10, CIFAR-100, and tiny-imagenet as well as two real-world datasets: plantvillage and chest X-ray in the presence of state-of-the-art adversarial attack techniques. We have also validated BEARR against a more potent attacker who has perfect knowledge of the protection mechanism. We observe that BEARR is significantly better than existing methods in the context of detection and classification accuracy of adversarial examples.