Agent Skills Enable a New Class of Realistic and Trivially Simple Prompt Injections

Fuente: arXiv
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Autori principali: Schmotz, David, Abdelnabi, Sahar, Andriushchenko, Maksym
Natura: Preprint
Pubblicazione: 2025
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author Schmotz, David
Abdelnabi, Sahar
Andriushchenko, Maksym
author_facet Schmotz, David
Abdelnabi, Sahar
Andriushchenko, Maksym
contents Enabling continual learning in LLMs remains a key unresolved research challenge. In a recent announcement, a frontier LLM company made a step towards this by introducing Agent Skills, a framework that equips agents with new knowledge based on instructions stored in simple markdown files. Although Agent Skills can be a very useful tool, we show that they are fundamentally insecure, since they enable trivially simple prompt injections. We demonstrate how to hide malicious instructions in long Agent Skill files and referenced scripts to exfiltrate sensitive data, such as internal files or passwords. Importantly, we show how to bypass system-level guardrails of a popular coding agent: a benign, task-specific approval with the "Don't ask again" option can carry over to closely related but harmful actions. Overall, we conclude that despite ongoing research efforts and scaling model capabilities, frontier LLMs remain vulnerable to very simple prompt injections in realistic scenarios. Our code is available at https://github.com/aisa-group/promptinject-agent-skills.
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id arxiv_https___arxiv_org_abs_2510_26328
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Agent Skills Enable a New Class of Realistic and Trivially Simple Prompt Injections
Schmotz, David
Abdelnabi, Sahar
Andriushchenko, Maksym
Machine Learning
Enabling continual learning in LLMs remains a key unresolved research challenge. In a recent announcement, a frontier LLM company made a step towards this by introducing Agent Skills, a framework that equips agents with new knowledge based on instructions stored in simple markdown files. Although Agent Skills can be a very useful tool, we show that they are fundamentally insecure, since they enable trivially simple prompt injections. We demonstrate how to hide malicious instructions in long Agent Skill files and referenced scripts to exfiltrate sensitive data, such as internal files or passwords. Importantly, we show how to bypass system-level guardrails of a popular coding agent: a benign, task-specific approval with the "Don't ask again" option can carry over to closely related but harmful actions. Overall, we conclude that despite ongoing research efforts and scaling model capabilities, frontier LLMs remain vulnerable to very simple prompt injections in realistic scenarios. Our code is available at https://github.com/aisa-group/promptinject-agent-skills.
title Agent Skills Enable a New Class of Realistic and Trivially Simple Prompt Injections
topic Machine Learning
url https://arxiv.org/abs/2510.26328