IAG: Input-aware Backdoor Attack on VLM-based Visual Grounding

Fuente: arXiv
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Main Authors: Li, Junxian, Xu, Beining, Chen, Simin, Li, Jiatong, Lei, Jingdi, Zhao, Haodong, Zhang, Di
Format: Preprint
Published: 2025
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author Li, Junxian
Xu, Beining
Chen, Simin
Li, Jiatong
Lei, Jingdi
Zhao, Haodong
Zhang, Di
author_facet Li, Junxian
Xu, Beining
Chen, Simin
Li, Jiatong
Lei, Jingdi
Zhao, Haodong
Zhang, Di
contents Recent advances in vision-language models (VLMs) have significantly enhanced the visual grounding task, which involves locating objects in an image based on natural language queries. Despite these advancements, the security of VLM-based grounding systems has not been thoroughly investigated. This paper reveals a novel and realistic vulnerability: the first multi-target backdoor attack on VLM-based visual grounding. Unlike prior attacks that rely on static triggers or fixed targets, we propose IAG, a method that dynamically generates input-aware, text-guided triggers conditioned on any specified target object description to execute the attack. This is achieved through a text-conditioned UNet that embeds imperceptible target semantic cues into visual inputs while preserving normal grounding performance on benign samples. We further develop a joint training objective that balances language capability with perceptual reconstruction to ensure imperceptibility, effectiveness, and stealth. Extensive experiments on multiple VLMs (e.g., LLaVA, InternVL, Ferret) and benchmarks (RefCOCO, RefCOCO+, RefCOCOg, Flickr30k Entities, and ShowUI) demonstrate that IAG achieves the best ASRs compared with other baselines on almost all settings without compromising clean accuracy, maintaining robustness against existing defenses, and exhibiting transferability across datasets and models. These findings underscore critical security risks in grounding-capable VLMs and highlight the need for further research on trustworthy multimodal understanding.
format Preprint
id arxiv_https___arxiv_org_abs_2508_09456
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle IAG: Input-aware Backdoor Attack on VLM-based Visual Grounding
Li, Junxian
Xu, Beining
Chen, Simin
Li, Jiatong
Lei, Jingdi
Zhao, Haodong
Zhang, Di
Computer Vision and Pattern Recognition
Computation and Language
Cryptography and Security
Recent advances in vision-language models (VLMs) have significantly enhanced the visual grounding task, which involves locating objects in an image based on natural language queries. Despite these advancements, the security of VLM-based grounding systems has not been thoroughly investigated. This paper reveals a novel and realistic vulnerability: the first multi-target backdoor attack on VLM-based visual grounding. Unlike prior attacks that rely on static triggers or fixed targets, we propose IAG, a method that dynamically generates input-aware, text-guided triggers conditioned on any specified target object description to execute the attack. This is achieved through a text-conditioned UNet that embeds imperceptible target semantic cues into visual inputs while preserving normal grounding performance on benign samples. We further develop a joint training objective that balances language capability with perceptual reconstruction to ensure imperceptibility, effectiveness, and stealth. Extensive experiments on multiple VLMs (e.g., LLaVA, InternVL, Ferret) and benchmarks (RefCOCO, RefCOCO+, RefCOCOg, Flickr30k Entities, and ShowUI) demonstrate that IAG achieves the best ASRs compared with other baselines on almost all settings without compromising clean accuracy, maintaining robustness against existing defenses, and exhibiting transferability across datasets and models. These findings underscore critical security risks in grounding-capable VLMs and highlight the need for further research on trustworthy multimodal understanding.
title IAG: Input-aware Backdoor Attack on VLM-based Visual Grounding
topic Computer Vision and Pattern Recognition
Computation and Language
Cryptography and Security
url https://arxiv.org/abs/2508.09456