Object detection has found extensive applications in various tasks, but it is also susceptible to adversarial patch attacks. The ideal defense should be effective, efficient, easy to deploy, and capable of withstanding adaptive attacks. In this paper, we adopt a counterattack strategy to propose a novel and general methodology for defending adversarial attacks. Two types of defensive patches, canary and woodpecker, are specially-crafted and injected into the model input to proactively probe or counteract potential adversarial patches. In this manner, adversarial patch attacks can be effectively detected by simply analyzing the model output, without the need to alter the target model. Moreover, we employ randomized canary and woodpecker injection patterns to defend against defense-aware attacks. The effectiveness and practicality of the proposed method are demonstrated through comprehensive experiments. The results illustrate that canary and woodpecker achieve high performance, even when confronted with unknown attack methods, while incurring limited time overhead. Furthermore, our method also exhibits sufficient robustness against defense-aware attacks, as evidenced by adaptive attack experiments.

Phishing is one of the most popular cyberspace attacks. Phishing detection has been integrated into mainstream browsers to provide online protection. The phishing detector of Google Chrome reports millions of phishing attacks per week. However, it has been proven to be vulnerable to evasion attacks. Currently, Google has upgraded Chrome/Chromium's phishing detector, introducing a CNN-based image classifier. The robustness of the new-generation detector is unclear. If it can be bypassed, its billions of users will be exposed to sophisticated attackers. This paper presents a critical evaluation of Google's phishing detector by targeted evasion testing, and investigates corresponding defensive techniques. First, we propose a three-stage evasion method against the phishing image classifier. The experiments show that it can be completely bypassed with adversarial phishing pages generated using the proposed method. Meanwhile, the phishing pages still preserve their visual utility. Second, we introduce two defense techniques to enhance the phishing detection model. The results show that even using lightweight defense methods can significantly improve the model robustness. Our research reveals that Google's new-generation phishing classifier is very vulnerable to targeted evasion attacks. A sophisticated phishers can know how to fool the classifier. Billions of Chrome users are being exposed to potential phishing attacks. To improve its robustness, necessary security enhancements should be introduced.