Browser agents have a blind spot: attacks designed to fool humans still work on them
AspireAI community · arXiv
Work on agentic browser security has focused on indirect prompt injection, which leaves out the classic web attacks that were built to trick people. This paper proposes a web-focused threat model for agentic browsers, derives a taxonomy of 20 attacks spanning the web and the LLM space, implements 18 of them, and extends the See-Act model to account for the whole browser, framing the agent as a confused deputy unable to distinguish task steps from ordinary web attacks. Ten of the web threats re-emerge often in amplified form once an agent can be influenced by untrusted page content, and a generalizability study across 14 attacks reproduces them on four major models from multiple vendors. The authors report five major failure modes and argue that agentic browsers need rearchitecting before they are ready for the current web. Note the version: this is a v2 revision of a May 2026 paper, so treat the threat model as current but the ecosystem claim as dated.
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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.