Towards Invisible Decision-Based Adversarial Attacks Against Visual Object Tracking

Adversarial attacks have become a critical focus in visual object tracking (VOT) research. Small, carefully crafted adversarial perturbations to video frames can easily disrupt the visual object tracker, leading to tracking failure. Therefore, studying adversarial attacks contributes to the development of more robust and reliable trackers. Considering that trackers are agnostic in real-world scenarios, research on decision-based black-box attacks is straightforward and practical. However, existing decision-based black-box attacks neither comprehensively analyze the unique characteristics of object tracking nor sufficiently consider the imperceptibility of adversarial perturbations. In this paper, we propose invisible local attack (ILA), a novel decision-based adversarial attack specifically for VOT with imperceptible perturbations. We assume that a significant number of pixels in a frame, irrelevant to the tracked object, do not substantially contribute to the functioning mechanism of a deep tracker. Based on this consideration, we propose a search algorithm to identify the pixel set focused on by the tracker during object tracking. The adversarial noise is then confined to these pixels and iteratively optimized through a heuristic algorithm of ILA. By perturbing only the key pixels, ILA significantly enhances both the attack performance and imperceptibility when it is applied to visual object trackers. Extensive experiments demonstrate that our ILA method achieves a 121% increase in the robustness metric and a 137% improvement in the structural similarity index measure (SSIM) across multiple datasets for various trackers compared with the state-of-the-art (SOTA) method.