The Task Shield: Enforcing Task Alignment to Defend Against Indirect Prompt Injection in LLM Agents

Fuente: arXiv
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Main Authors: Jia, Feiran, Wu, Tong, Qin, Xin, Squicciarini, Anna
Format: Preprint
Published: 2024
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author Jia, Feiran
Wu, Tong
Qin, Xin
Squicciarini, Anna
author_facet Jia, Feiran
Wu, Tong
Qin, Xin
Squicciarini, Anna
contents Large Language Model (LLM) agents are increasingly being deployed as conversational assistants capable of performing complex real-world tasks through tool integration. This enhanced ability to interact with external systems and process various data sources, while powerful, introduces significant security vulnerabilities. In particular, indirect prompt injection attacks pose a critical threat, where malicious instructions embedded within external data sources can manipulate agents to deviate from user intentions. While existing defenses based on rule constraints, source spotlighting, and authentication protocols show promise, they struggle to maintain robust security while preserving task functionality. We propose a novel and orthogonal perspective that reframes agent security from preventing harmful actions to ensuring task alignment, requiring every agent action to serve user objectives. Based on this insight, we develop Task Shield, a test-time defense mechanism that systematically verifies whether each instruction and tool call contributes to user-specified goals. Through experiments on the AgentDojo benchmark, we demonstrate that Task Shield reduces attack success rates (2.07\%) while maintaining high task utility (69.79\%) on GPT-4o.
format Preprint
id arxiv_https___arxiv_org_abs_2412_16682
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Task Shield: Enforcing Task Alignment to Defend Against Indirect Prompt Injection in LLM Agents
Jia, Feiran
Wu, Tong
Qin, Xin
Squicciarini, Anna
Cryptography and Security
Artificial Intelligence
Computation and Language
Machine Learning
Large Language Model (LLM) agents are increasingly being deployed as conversational assistants capable of performing complex real-world tasks through tool integration. This enhanced ability to interact with external systems and process various data sources, while powerful, introduces significant security vulnerabilities. In particular, indirect prompt injection attacks pose a critical threat, where malicious instructions embedded within external data sources can manipulate agents to deviate from user intentions. While existing defenses based on rule constraints, source spotlighting, and authentication protocols show promise, they struggle to maintain robust security while preserving task functionality. We propose a novel and orthogonal perspective that reframes agent security from preventing harmful actions to ensuring task alignment, requiring every agent action to serve user objectives. Based on this insight, we develop Task Shield, a test-time defense mechanism that systematically verifies whether each instruction and tool call contributes to user-specified goals. Through experiments on the AgentDojo benchmark, we demonstrate that Task Shield reduces attack success rates (2.07\%) while maintaining high task utility (69.79\%) on GPT-4o.
title The Task Shield: Enforcing Task Alignment to Defend Against Indirect Prompt Injection in LLM Agents
topic Cryptography and Security
Artificial Intelligence
Computation and Language
Machine Learning
url https://arxiv.org/abs/2412.16682