arXiv Computation and Language

Conformal Privacy Auditing: Calibrated Re-identification Attacks with Statistical Guarantees

Conformal Privacy Auditing (CPA) is a distribution‑free framework that calibrates re‑identification risk for each released document against large language model (LLM)‑empowered adversaries. It outputs a conformal ambiguity set of candidate identities that is guaranteed to contain the true identity with a user‑chosen confidence level under exchangeability, along with an interpretable leakage proxy derived from the set size. CPA supports both logit‑access and sampling‑only attackers, enabling audits of both open‑source and proprietary models, and demonstrates calibrated coverage across various benchmarks and attacker configurations.

arXiv Machine Learning
Oct 19

The LLM-Attacker: A Unified Red-Team Framework for Privacy Evaluation of Split and Distributed LLM Systems

The paper introduces LLM‑Attacker, a unified framework for evaluating privacy risks in split and distributed large language models. It records attacker choices—such as message types, model weights, datasets, and recovery metrics—to enable consistent comparison and extension of privacy evaluations. Experiments on GPT‑2 show that providing training gradients boosts token recovery from 94.20% to 97.38% and exact‑document recovery from 13.71% to 37.77%, illustrating the framework’s ability to quantify how changes in attacker access affect privacy outcomes.

By Georgios Politis, Evangelos Pappas
arXiv Machine Learning
Oct 21

LLM-Attack Suite: A Unified Red-Team Framework for Privacy Evaluation of Split and Distributed LLM Systems

The paper introduces LLM‑Attack Suite, a unified framework for evaluating privacy risks in split and distributed large language models. It records attacker choices—such as message types, model weights, datasets, and recovery metrics—to enable consistent comparison and extension of privacy evaluations. Experiments on GPT‑2 demonstrate that providing gradients during training significantly boosts token and document recovery rates, illustrating how attacker access levels influence privacy outcomes.

By Georgios Politis, Evangelos Pappas
arXiv Machine Learning
Aug 27

Retrieved But Not Reliable: A Survey on Attacks, and Defenses in Retrieval-Augmented Generation

The paper surveys attacks and defenses in Retrieval-Augmented Generation (RAG), a technique that improves large language models by grounding outputs in external knowledge. It identifies new robustness and security risks such as corpus poisoning, backdoor attacks, privacy leakage, and fairness violations, and notes that existing surveys inadequately cover attacker objectives, threat models, and stage-specific defenses. The survey offers a unified, pipeline-aware overview, formalizing threat models across the corpus, retriever, and generator, categorizing attacks by accuracy, privacy, and fairness, and reviewing defenses for retrieval, rerank, generation, and traceback stages, while also summarizing robustness benchmarks and explainability methods.

By Minh Tran, Cuong Dang, Tuc Nguyen, Khanh-Tung Tran, Minh Huynh Nguyen, Trinh Chau, Kien Le, Do Xuan Long, Jiahao Zhang, Hoang D. Nguyen, Thanh Le, Suhang Wang
arXiv Machine Learning
Aug 27

Reconstruction of Personally Identifiable Information from Proprietary Data in Supervised Fine-Tuned Models

The paper examines how supervised fine-tuning (SFT) of large language models can leak personally identifiable information (PII) when the fine-tuning data contains user-provided sensitive details. It introduces COVA, a coverage-aware decoding algorithm that improves targeted PII reconstruction from SFT models, especially when an adversary has limited contextual knowledge about a target. Experiments on medical and legal Q&A datasets show that even small proprietary SFT datasets can lead to significant privacy leakage via PII reconstruction.

By Sae Furukawa, Alina Oprea