arXiv AI

Membership Inference Attacks on Recommender System: A Survey

The article surveys membership inference attacks (MIAs) on recommender systems (RecSys), highlighting how these attacks can reveal whether a user’s interaction record was used in training and thus pose privacy risks. It reviews recent advances, design principles, challenges, and defense strategies specific to RecSys, noting that traditional MIAs are ill‑suited due to unseen posterior probabilities. The survey presents a unified taxonomy of RecSys MIAs, discusses their pros and cons, and outlines future research directions.

arXiv AI
Oct 16

On the Privacy of LLMs: An Ablation Study

The paper examines privacy risks in large language models (LLMs) through a unified threat model and systematic ablation study of four attacks: Membership Inference, Attribute Inference, Data Extraction, and Backdoor Attacks. It finds that membership inference is highly sensitive to dataset and attack strategy, attribute inference depends on model and training characteristics, data extraction grows with model size and repeated training data, and backdoor attacks consistently succeed. The authors provide practical recommendations for privacy‑aware LLM deployment, such as prioritizing membership leakage checks in retrieval‑augmented systems, reducing repeated personal data in training, monitoring attribute inference, and protecting fine‑tuning pipelines from backdoors.

By Karima Makhlouf, Lamiaa Basyoni, Syed Khaderi, Gabriel Marquez, Peter Sotomango, Mahmoud Awawdah, Sami Zhioua
arXiv Machine Learning
Sep 11

Empirical Evaluation of Membership Inference Attacks on NLP Text Classifiers: A Baseline Study on SST-2

The paper evaluates membership inference attacks (MIAs) on NLP text classifiers using the GLUE SST‑2 sentiment dataset. It compares a TF‑IDF + Logistic Regression pipeline with a fine‑tuned DistilBERT model under a loss‑threshold MIA, finding that both models leak membership signals despite high accuracy. The study also tests mitigations, showing that stronger regularization reduces leakage for Logistic Regression at a utility cost, while fine‑tuning DistilBERT for fewer epochs lowers leakage with minimal accuracy loss.

By William Novak (Minot State University), Muhammad Abusaqer (Minot State University)
arXiv Machine Learning
Sep 14

Membership Inference via Pairwise Likelihood Ratios

The paper introduces Pairwise Likelihood MIA (PL‑MIA), a unified membership inference attack that combines a Gaussian likelihood‑ratio statistic with population calibration and the Cauchy combination test. PL‑MIA generates p‑values from pairwise comparisons between a query point and reference points, then aggregates these continuous signals using the Cauchy test to preserve evidence strength. Experiments show that PL‑MIA surpasses strong baselines, boosting true positive rates by over 25% in low‑false‑positive settings, thereby validating the theoretical advantages of the proposed statistical framework.

By Shengjie Niu, Zebin Yun, Yeheng Ge, Jian Huang
arXiv AI
Oct 16

Encoded but Exposed: Language Embeddings can Reveal More Than They Should in Recommender Systems

The paper investigates privacy risks of language embeddings used in recommender systems. It demonstrates that a simple cosine‑similarity attack can recover item identities with high accuracy when an adversary has auxiliary text, even when the descriptions are independently sourced. The study also shows that such leakage can lead to user re‑identification from sparse ratings and evaluates obfuscated descriptions as a mitigation, revealing a trade‑off between privacy and utility.

By Linda Bekov\'a, Rodrigo Alves
arXiv Machine Learning
Jul 3

Embedding Inference Attack

arXiv:2607. 01276v1 Announce Type: cross Abstract: Embedding models are essential components of modern Information Retrieval (IR) systems, yet they are typically hidden behind APIs.

By Cedric Fitiavana Raelijohn, S\'ebastien Gambs, Jean-Francois Rajotte