The transferability of adversarial examples (AEs) across diverse models is of critical importance for black-box adversarial attacks, where attackers cannot access the information about black-box models. However, crafted AEs always present poor transferability. In this paper, by regarding the transferability of AEs as generalization ability of the model, we reveal that vanilla black-box attacks craft AEs via solving a maximum likelihood estimation (MLE) problem. For MLE, the results probably are model-specific local optimum when available data is small, i.e., limiting the transferability of AEs. By contrast, we re-formulate crafting transferable AEs as the maximizing a posteriori probability estimation problem, which is an effective approach to boost the generalization of results with limited available data. Because Bayes posterior inference is commonly intractable, a simple yet effective method called MaskBlock is developed to approximately estimate. Moreover, we show that the formulated framework is a generalization version for various attack methods. Extensive experiments illustrate MaskBlock can significantly improve the transferability of crafted adversarial examples by up to about 20%.

翻译：不同模型的对抗性实例(AEs)的可转让性对于黑盒对抗性攻击至关重要,因为攻击者无法获取黑盒对抗性攻击,攻击者无法获取黑盒对抗性攻击模式的信息。然而,所设计的AEs总是不能很好地进行转移。在本文中,通过将AEs可转让性作为模型的概括性能力,我们发现香草黑箱攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性攻击性