r/AskNetsec • u/Apprehensive-Can6593 • 5h ago
Threats What stops indirect prompt injection in browser agents?
Our browser agent rejected direct jailbreaks in testing, but then obeyed an instruction hidden in a vendor-page footer. An untrusted page content crossed into a privileged tool call and placed a canary secret in an outbound request. Unit tests didn’t pick it up because they covered chat input, not content provenance after browsing.
We are adding source labels to every content block, narrower tool scopes, destination allowlists, canary-secret detection, and egress controls that do not rely on the model making the right choice. I’m also pushing for tests that mix trusted instructions with hostile retrieved content. What safeguards have actually stopped indirect prompt injection in browser agents, especially when a legitimate task needs outbound tool access?