Trusted Device Cookie
A07 · ≈ 35 min · 0 solves
Explore the application as a real target: map the exposed functionality, inspect requests and responses, build a working exploit, and recover the rotating flag. If you get stuck, the verified official solution is available below as an optional spoiler.
Rules of engagement
Stay inside the generated lab URL. Use only the synthetic accounts and data in this instance. The main SecOne4all site and external systems are out of scope.
Challenge brief
What counts as a valid solve
A device-trust decision relies on a client-controlled cookie.
GET /device.
reach the protected synthetic account state without completing the intended authentication boundary; the successful workflow returns the current rotating flag.
Work only inside your generated lab URL and submit the flag within 35 minutes.
Official solution
Contains the complete exploitation path. Open it only when you want the spoiler.
Reveal official solutionStep-by-step · verified against the live lab
Official solution · A07 · Trusted Device Cookie
Objective
A device-trust decision relies on a client-controlled cookie.
Steps
- Start the isolated lab and inspect the advertised authentication or recovery entry point.
- Complete the normal first step to obtain the synthetic session, token, or account state.
- Exploit the authentication failure: GET
/devicewith cookietrusted_device=admin-approved. - Confirm the bypassed identity boundary returns the rotating instance flag.
- Submit the exact flag before stopping the lab.
Expected proof
A successful response for device-trust-spoof returns the instance-specific rotating flag. The flag is valid only for the current player and running instance.
Safety boundary
Use only the generated lab URL. No request to the main site, another user, or an external service is part of this solution.