BragJack: Malicious Extensions Hijack Browser AI
π Security researcher Gal Weizman of Forever Security disclosed a proof-of-concept attack named BragJack that uses a single malicious Chromium extension to hijack built-in AI browser agents. The technique, demonstrated against Chrome Gemini Live, Perplexity Comet, Microsoft Edge, Opera Neon, and Claude for Chrome, exploits Chromium's declarativeNetRequest to intercept and modify trusted resources, enabling agents to access files, history, screenshots, and act on users' behalf. Vendors issued fixes and paid bug bounties, and the researcher published a full technical breakdown.