Implicit Jailbreak Attacks via Cross-Modal Information Concealment on Vision-Language Models

Fuente: arXiv
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Main Authors: Wang, Zhaoxin, Wang, Handing, Tian, Cong, Jin, Yaochu
Format: Preprint
Published: 2025
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author Wang, Zhaoxin
Wang, Handing
Tian, Cong
Jin, Yaochu
author_facet Wang, Zhaoxin
Wang, Handing
Tian, Cong
Jin, Yaochu
contents Multimodal large language models (MLLMs) enable powerful cross-modal reasoning capabilities. However, the expanded input space introduces new attack surfaces. Previous jailbreak attacks often inject malicious instructions from text into less aligned modalities, such as vision. As MLLMs increasingly incorporate cross-modal consistency and alignment mechanisms, such explicit attacks become easier to detect and block. In this work, we propose a novel implicit jailbreak framework termed IJA that stealthily embeds malicious instructions into images via least significant bit steganography and couples them with seemingly benign, image-related textual prompts. To further enhance attack effectiveness across diverse MLLMs, we incorporate adversarial suffixes generated by a surrogate model and introduce a template optimization module that iteratively refines both the prompt and embedding based on model feedback. On commercial models like GPT-4o and Gemini-1.5 Pro, our method achieves attack success rates of over 90% using an average of only 3 queries.
format Preprint
id arxiv_https___arxiv_org_abs_2505_16446
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Implicit Jailbreak Attacks via Cross-Modal Information Concealment on Vision-Language Models
Wang, Zhaoxin
Wang, Handing
Tian, Cong
Jin, Yaochu
Machine Learning
Multimodal large language models (MLLMs) enable powerful cross-modal reasoning capabilities. However, the expanded input space introduces new attack surfaces. Previous jailbreak attacks often inject malicious instructions from text into less aligned modalities, such as vision. As MLLMs increasingly incorporate cross-modal consistency and alignment mechanisms, such explicit attacks become easier to detect and block. In this work, we propose a novel implicit jailbreak framework termed IJA that stealthily embeds malicious instructions into images via least significant bit steganography and couples them with seemingly benign, image-related textual prompts. To further enhance attack effectiveness across diverse MLLMs, we incorporate adversarial suffixes generated by a surrogate model and introduce a template optimization module that iteratively refines both the prompt and embedding based on model feedback. On commercial models like GPT-4o and Gemini-1.5 Pro, our method achieves attack success rates of over 90% using an average of only 3 queries.
title Implicit Jailbreak Attacks via Cross-Modal Information Concealment on Vision-Language Models
topic Machine Learning
url https://arxiv.org/abs/2505.16446