arXiv AI

Cost-Efficient Privacy Enforcement for Email-Generating LLM Agents under Strategic Information Requests

The paper proposes a cost‑efficient privacy enforcement method for email‑generating large language model (LLM) agents that intercepts drafts, creates an information‑release contract, rewrites the draft locally with a Gemma rewriter, and then optionally calls a final PrivacyChecker. Experiments on normal and strategically malicious prompts show that the Gemma + Checker approach reduces leakage from 11.41 % to 4.03 % and improves usable output rates, while also cutting the cost amplification of checker‑only pipelines from 1.32× to 1.02×. The results demonstrate that moving repair to a cheaper local layer can significantly lower both privacy leakage and operational cost, yet still rely on a checker for high‑risk sends.

arXiv AI
Oct 31

Judging Before Propagation: Task-Graph Contextual Integrity for Multi-Agent Privacy

The paper introduces Task-Graph Contextual Integrity (TG‑CI), a formalism that extends traditional Contextual Integrity to multi‑agent systems by modeling workflows as Multi‑Agent Task Graphs (MATGs). TG‑CI evaluates privacy not just at individual disclosures but across the entire downstream propagation, offering two enforcement policies—Full‑Scope and Auto‑Region—that balance privacy protection with task performance. A new benchmark, MAPLE‑Bench, demonstrates that TG‑CI can cut unauthorized disclosures by up to 94% while preserving over 94% of task accuracy compared to existing local‑history CI methods.

By Hengyu Wu, Blaise Delattre, Yang Cao
arXiv Computer Vision
Sep 14

BodhiPromptShield: Pre-Inference Prompt Mediation for Surface-Form Privacy Propagation in LLM Agent Pipelines

BodhiPromptShield is a policy‑aware mediation layer for LLM agent pipelines that detects sensitive text spans before they propagate, replacing them with typed placeholders, semantic abstractions, or secure tokens and restoring them only at authorized execution boundaries. In evaluations on AI4Privacy, PrivacyLens, and AgentDojo datasets, the system reduces identifier exposure to 7.4% and 1.8% respectively, and limits exact identifier leakage in final actions to 2.1–3.1%. While mediation preserves factual content according to automated metrics, human annotations show a significant drop in inferability from 100% to 24–53%, indicating the need for human validation of semantic‑leakage measures.

By Bo Ma, Jinsong Wu, Weiqi Yan
arXiv AI
Oct 16

Approve What, Exactly? Effect Binding and Trusted Rendering for Agent Step-Up Authorization

The paper "Approve What, Exactly? Effect Binding and Trusted Rendering for Agent Step-Up Authorization" examines how AI agents seek approval before performing actions such as sending money or deleting files. It identifies twelve attack vectors on the approval process and evaluates them against several protocols, finding that many agent runtimes lack verifiable approval records and exhibit binding weaknesses. The authors propose a defense called ASU (Agent Step-Up), which renders a canonical approval card, requires a phone passkey, and enforces single-use execution, demonstrating strong protection against substitution, replay, and grant-stretching attacks in extensive simulations.

By Sai Varun Kodathala, Prashanth Pollishetty, Jaylen Cargill
arXiv AI
Oct 7

APEX: Active Protection at Execution Boundaries for LLM Agents

The paper introduces APEX, an active defense for large language model agents that protects against indirect prompt injection by enforcing safety at execution boundaries. APEX uses an evidence‑gated prevention contract and deception‑based exposure to ensure that only authorized effects, endorsed by the task, are executed. Evaluation shows APEX achieves near‑zero attack success across multiple benchmarks and capability‑unit types, outperforming 13 baseline defenses.

By Xinran Zheng, Xin Fan Guo, Zhiqiang Hao, Fan Yang, Xingzhi Qian, Jiawei Du, Jinfeng Xu, Zheng Xing, Shuo Yang, Xingjun Wang