Practice Arena / Broken Access Control
Hard ⭐ 200 pts Access Control IDOR

Broken Access Control (IDOR)

Access resources belonging to other users by manipulating direct object references. Exposes confidential data through predictable IDs.

Hint

The API returns user data based on the ?id= parameter in the URL. The server doesn't verify whether the requesting user is authorized to access that specific resource. What happens when you change the ID?

Objective

  • You are currently logged in as user_id = 1
  • Enumerate other user IDs to find a privileged account
  • Access that user's private data to reveal the flag
  • Submit the flag below to claim your 200 points

Submit Flag

// API request

GET /api/user?id= 1
UserProfile API v2.1
U

Normal User

role: user

user_id

1

email

user@app.com

private_data

[ access denied ]

ID: 1
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