Research

PR-Attack: Coordinated Prompt-RAG Attacks on Retrieval-Augmented Generation in Large Language Models via Bilevel Optimization | Proceedings of the 48th International ACM SIGIR Conference on Research and Development in Information Retrieval

Page published

Coverage timeline

15 Jul 2026acm.orgobserved 11 Aug 2026acm.orgobserved 24 Sep 2026acm.orgobserved

Why it matters

RAG corpus poisoning that stays fluent and evades perplexity filters lets attackers steer LLM answers at very low poisoning ratios (0.016% in a 21M-passage corpus), undermining the integrity of retrieval-augmented deployments defenders increasingly rely on.

A SIGIR 2025 research paper (titled PR-Attack, describing a method called SilentRetrieval) presents a two-stage data-poisoning attack that hijacks Retrieval-Augmented Generation systems using adversarially crafted but fluent documents. It combines Coordinated Beam Search to keep poisoned host documents retrievable while constraining perplexity and Context-Adaptive Trigger Generation to fuse triggers with content, achieving up to 84.6% HR@10 and 57.5% ASR-LLM on Natural Questions and MS MARCO, with cross-model and cross-retriever transfer including ColBERT and commercial embedding models.