The RAG Paradox: A Black-Box Attack Exploiting Unintentional Vulnerabilities in Retrieval-Augmented Generation Systems

With the growing adoption of retrieval-augmented generation (RAG) systems, recent studies have introduced attack methods aimed at degrading their performance. However, these methods rely on unrealistic white-box assumptions, such as attackers having access to RAG systems' internal processes. To address this issue, we introduce a realistic black-box attack scenario based on the RAG paradox, where RAG systems inadvertently expose vulnerabilities while attempting to enhance trustworthiness. Because RAG systems reference external documents during response generation, our attack targets these sources without requiring internal access. Our approach first identifies the external sources disclosed by RAG systems and then automatically generates poisoned documents with misinformation designed to match these sources. Finally, these poisoned documents are newly published on the disclosed sources, disrupting the RAG system's response generation process. Both offline and online experiments confirm that this attack significantly reduces RAG performance without requiring internal access. Furthermore, from an insider perspective within the RAG system, we propose a re-ranking method that acts as a fundamental safeguard, offering minimal protection against unforeseen attacks.