Vulnerabilities
BragJack: Malicious Extension Hijacks AI Browser Assistants
A proof‑of‑concept attack named BragJack demonstrates how a single malicious browser extension can hijack AI assistants in Chrome, Edge, Opera Neon, Perplexity Comet, and Claude in Chrome. The technique abuses browser‑level privileges, allowing the attacker to read data and act on the user’s behalf without interaction. Defenders should remove suspicious extensions, enforce strict extension policies, and keep browsers updated.
BragJack is a proof‑of‑concept that shows a malicious extension can take control of AI assistants built into Chromium‑based browsers.
What Happened
The attacker installs a single extension that, once present, can issue commands to the AI assistant and leverage its browser privileges. The proof‑of‑concept targeted Gemini Live in Chrome, Microsoft Edge, Opera Neon, Perplexity Comet, and Claude in Chrome.
Affected Systems
- Google Chrome (Gemini Live)
- Microsoft Edge
- Opera Neon
- Perplexity Comet
- Claude in Chrome
Impact
Once hijacked, the AI assistant can read or exfiltrate sensitive data, execute arbitrary browser actions, and act on the user’s behalf without any additional interaction.
What to Do
- Audit and remove any untrusted or unknown extensions.
- Configure browsers to allow extensions only from verified sources.
- Keep browsers and extensions up to date; vendors have patched the CVEs.
- Monitor for unusual AI assistant activity and restrict its permissions where possible.
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