Title: Stop Tracking Me! Proactive Defense Against Attribute Inference Attack in LLMs
Primary area: alignment, fairness, safety, privacy, and societal considerations
Keywords: Privacy leakage;Inference-preventing optimization;Text anonymization;Attribute inference attack;Large language models

Abstract: Recent studies have shown that large language models (LLMs) can infer private user attributes (e.g., age, location, gender) from user-generated text shared online, enabling rapid and large-scale privacy breaches. Existing anonymization-based defenses are coarse-grained, lacking word-level precision in anonymizing privacy-leaking elements. Moreover, they are inherently limited as altering user text to hide sensitive cues still allows attribute inference to occur through models' reasoning capabilities.
To address these limitations, we propose a unified defense framework that combines fine-grained anonymization (TRACE) with inference-preventing optimization (RPS). TRACE leverages attention mechanisms and inference chain generation to identify and anonymize privacy-leaking textual elements, while RPS employs a lightweight two-stage optimization strategy to induce model rejection behaviors, thereby preventing attribute inference. 
Evaluations across diverse LLMs show that TRACE-RPS reduces attribute inference accuracy from around 50\% to below 5\% on open-source models. In addition, our approach offers strong cross-model generalization, prompt-variation robustness, and utility-privacy tradeoffs.

TL;DR: We propose TRACE-RPS, a proactive, unified defense framework that combines fine-grained text anonymization and optimized perturbation to effectively prevent attribute inference attacks in large language models.