Towards More Realistic Extraction Attacks: An Adversarial Perspective (2407.02596v2)

Abstract: LLMs are prone to memorizing parts of their training data which makes them vulnerable to extraction attacks. Existing research often examines isolated setups--such as evaluating extraction risks from a single model or with a fixed prompt design. However, a real-world adversary could access models across various sizes and checkpoints, as well as exploit prompt sensitivity, resulting in a considerably larger attack surface than previously studied. In this paper, we revisit extraction attacks from an adversarial perspective, focusing on how to leverage the brittleness of LLMs and the multi-faceted access to the underlying data. We find significant churn in extraction trends, i.e., even unintuitive changes to the prompt, or targeting smaller models and earlier checkpoints, can extract distinct information. By combining information from multiple attacks, our adversary is able to increase the extraction risks by up to $2 \times$. Furthermore, even with mitigation strategies like data deduplication, we find the same escalation of extraction risks against a real-world adversary. We conclude with a set of case studies, including detecting pre-training data, copyright violations, and extracting personally identifiable information, showing how our more realistic adversary can outperform existing adversaries in the literature.