Exploiting Pre-Trained Models and Low-Frequency Preference for Cost-Effective Transfer-based Attack

The transferability of adversarial examples enables practical transfer-based attacks. However, existing theoretical analysis cannot effectively reveal what factors contribute to cross-model transferability. Furthermore, the assumption that the target model dataset is available together with expensive prices of training proxy models also leads to insufficient practicality. We first propose a novel frequency perspective to study the transferability and then identify two factors that impair the transferability: an unchangeable intrinsic difference term along with a controllable perturbation-related term. To enhance the transferability, an optimization task with the constraint that decreases the impact of the perturbation-related term is formulated and an approximate solution for the task is designed to address the intractability of Fourier expansion. To address the second issue, we suggest employing pre-trained models as proxy models, which are freely available. Leveraging these advancements, we introduce cost-effective transfer-based attack ( CTA ), which addresses the optimization task in pre-trained models. CTA can be unleashed against broad applications, at any time, with minimal effort and nearly zero cost to attackers . This remarkable feature indeed makes CTA an effective, versatile, and fundamental tool for attacking and understanding a wide range of target models, regardless of their architecture or training dataset used. Extensive experiments show impressive attack performance of CTA across various models trained in seven black-box domains, highlighting the broad applicability and effectiveness of CTA .