Reading a model's own responses was enough to find semantically vulnerable image regions and transfer adversarial examples to unseen commercial models at up to 97 percent attack success
AspireAI community · arXiv
Transferable black-box attacks on multimodal models typically allocate perturbations using surrogate-model saliency, which need not reflect how an unseen model semantically interprets or relies on different image regions. VISTA identifies semantically vulnerable regions purely from an MLLM's responses, with no access to gradients, logits, parameters or internal representations, by building an Uncertainty-Based Multimodal Behavior map from response drift, conflict, misleading answers and semantic shifts, then routing perturbations with entropy-adaptive Sinkhorn routing and a surrogate ensemble. The authors report up to 97 percent attack success rate across GPT-5, Gemini-3.5-Flash and Claude Sonnet 4.6 while keeping peak signal-to-noise ratio above 30 dB, and the pure-transfer variant reaches up to 93 percent attack success without ever querying the final victim, which is the result that makes the threat model cheap. The honest limitation is that this measures a white-box-of-the-response setting against models that were, in practice, adversarially fine-tuned or otherwise reachable, and the paper does not report whether a hardened defense closes the gap.
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Two sparse-autoencoder analyses have resisted scaling: matching semantically similar features across layers, and compressing large feature circuits into interpretable supernodes. This paper argues both are the same underlying problem, estimating semantic distances between SAE features that sit on different activation manifolds. Its representation treats each feature not as a single decoder vector but as an activation-weighted distribution over the hidden states expressing it, projects those distributions into a shared reference space, and compares them with Wasserstein distance. The representation is proved invariant to activation rescaling and stable under perturbation, and recovers true matches under finite-sample margin conditions. Empirically it outperformed decoder-vector and LLM-based baselines and captured subtle functional distinctions between related features, and it compressed large feature circuits into interpretable supernodes automatically. The limitation is that this is interpretability tooling: the paper demonstrates better feature matching and circuit compression, not that downstream interpretability claims become more accurate.