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Ottergram (BAC + HTTP Verb Tampering) — Bugforge

EN medium CTF challenge BACBroken Access ControlHTTP Verb TamperingIDORAuthorization BypassBurp Suite

Ottergram is a social-media-style web application on Bugforge.io where users browse otter photos. The attack chain is two-stage: first, find functionality you shouldn't be able to reach. Then, find a way past the gate that's supposed to stop you.

0/5
solved
👁 Step 1 Step 2 Step 3 Step 4 Step 5
post_exploitation

Step 5 · Exploit Admin Access — Perform Unauthorised Admin Action

Objective: Use the verb-tampered request to perform an admin-level action — such as reading other users' data, deleting posts, or modifying user roles — to demonstrate the full impact of the BAC + Verb Tampering chain.

Context: You now have a working bypass: a specific HTTP verb on the admin endpoint returns 200 as a regular user. Demonstrate the real-world impact by performing an action only an admin should be allowed to do.

Progressive hints

Only reveal the ones you need. Claude tracks how many you used to calibrate the feedback.

Hint 1 — directional nudge

What admin actions can you now trigger? Try reading sensitive user data, modifying another user's content, or escalating privileges — all using the verb-tampered request as your template in Burp Repeater.

Hint 2 — technique / vuln class

Replay the successful verb-tampered request but adjust the endpoint path or body to target admin actions: listing all users, viewing private posts, or performing moderation tasks.

Hint 3 — near solution

Use the bypass method (the working HTTP verb) to navigate admin sub-endpoints. For example, if /api/admin/users returned 200, try fetching individual user data, accessing post moderation, or reading private content that is not visible in the normal user feed.

Your attempt