Anomaly Unveiled: Securing Image Classification against Adversarial
  Patch Attacks
Nandish Chattopadhyay Amira Guesmi Muhammad Shafique
Adversarial patch attacks pose a significant threat to the practical
deployment of deep learning systems. However, existing research primarily
focuses on image pre-processing defenses, which often result in reduced
classification accuracy for clean images and fail to effectively counter
physically feasible attacks. In this paper, we investigate the behavior of
adversarial patches as anomalies within the distribution of image information
and leverage this insight to develop a robust defense strategy. Our proposed
defense mechanism utilizes a clustering-based technique called DBSCAN to
isolate anomalous image segments, which is carried out by a three-stage
pipeline consisting of Segmenting, Isolating, and Blocking phases to identify
and mitigate adversarial noise. Upon identifying adversarial components, we
neutralize them by replacing them with the mean pixel value, surpassing
alternative replacement options. Our model-agnostic defense mechanism is
evaluated across multiple models and datasets, demonstrating its effectiveness
in countering various adversarial patch attacks in image classification tasks.
Our proposed approach significantly improves accuracy, increasing from 38.8\%
without the defense to 67.1\% with the defense against LaVAN and GoogleAp
attacks, surpassing prominent state-of-the-art methods such as LGS (53.86\%)
and Jujutsu (60\%)