Fall Leaf Adversarial Attack on Traffic Sign Classification
Anthony Etim, Jakub Szefer
TL;DR
Traffic sign classification in autonomous systems is vulnerable to adversarial perturbations, and this work proposes a novel fall leaf attack that uses natural leaves as inconspicuous perturbations to induce misclassification. The approach overlays leaves on signs, optimizing location, size, color, and orientation via a grid-search framework and customized leaf masks, evaluated on the LISA-CNN model. Results show high-confidence misclassifications for several signs, with strong dependence on leaf type and placement and measurable changes in edge-detection metrics that correlate with attack success. The study highlights a new real-world threat vector and motivates edge-aware defenses and robust TSR methods to ensure reliable autonomous perception under natural environmental perturbations.
Abstract
Adversarial input image perturbation attacks have emerged as a significant threat to machine learning algorithms, particularly in image classification setting. These attacks involve subtle perturbations to input images that cause neural networks to misclassify the input images, even though the images remain easily recognizable to humans. One critical area where adversarial attacks have been demonstrated is in automotive systems where traffic sign classification and recognition is critical, and where misclassified images can cause autonomous systems to take wrong actions. This work presents a new class of adversarial attacks. Unlike existing work that has focused on adversarial perturbations that leverage human-made artifacts to cause the perturbations, such as adding stickers, paint, or shining flashlights at traffic signs, this work leverages nature-made artifacts: tree leaves. By leveraging nature-made artifacts, the new class of attacks has plausible deniability: a fall leaf stuck to a street sign could come from a near-by tree, rather than be placed there by an malicious human attacker. To evaluate the new class of the adversarial input image perturbation attacks, this work analyses how fall leaves can cause misclassification in street signs. The work evaluates various leaves from different species of trees, and considers various parameters such as size, color due to tree leaf type, and rotation. The work demonstrates high success rate for misclassification. The work also explores the correlation between successful attacks and how they affect the edge detection, which is critical in many image classification algorithms.
