Hey guys, Rocky here! 🕵️♂️🔓
Welcome to Day 13 of the Daily Web Hacking series! Today, we’re diving into Part 13: IDOR (Insecure Direct Object References)—the vulnerability that lets attackers steal data, hijack accounts, and wreak havoc by simply tweaking a number in a URL. Think of it as finding a master key that unlocks every door in a building. Let’s break down why IDOR is the lazy hacker’s goldmine and how you can defend against it.
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What is IDOR?
Insecure Direct Object References (IDOR) occur when an app exposes internal object identifiers (like user IDs, order numbers, or filenames) and fails to validate if the user has permission to access them. Attackers manipulate these identifiers to:
- Access unauthorized data (e.g., other users’ emails, invoices, medical records).
- Modify or delete resources (e.g., change someone’s password, cancel orders).
- Escalate privileges (e.g., from user to admin).
Why it’s dangerous:
- #1 in the OWASP Top 10’s Broken Access Control category (2021).
- Found in 60% of web apps (Veracode, 2023).
- Requires minimal skill—no fancy tools needed!
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How IDOR Works: The Master Key Analogy
Imagine a hotel where every room key is labeled with a sequential number (101, 102, 103…). If you’re given key #105, you could easily try #106 to access another room. That’s IDOR in a nutshell:
Example:
A site loads user profiles via:
https://hacklivly.com/profile?user_id=123
Change user_id=123 to user_id=124, and you’re viewing another user’s private data.
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Types of IDOR Attacks
1. Horizontal IDOR
- What: Access resources of another user at the same privilege level.
- Example: User A (ID=100) views User B’s (ID=101) tax documents.
2. Vertical IDOR
What: Access resources at a higher privilege level.
Example: A regular user accesses an admin panel by guessing the endpoint:
https://hacklivly.com/admin/dashboard?admin_id=1
3. Indirect IDOR
- What: Exploit non-numeric identifiers (e.g., usernames, UUIDs).
- Example: Change
/download?file=rocky.jpg to /download?file=admin.jpg.
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Real-World IDOR Disasters
- Facebook (2018): IDOR in the “View As” feature exposed 50M accounts.
- Uber (2016): Attackers modified rider IDs to take free trips.
- Telegram (2020): IDOR allowed access to private group chats.
Lesson: A single missing permission check can cost millions.
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Step-by-Step Exploitation
Goal: Steal another user’s order history.
1. Find an Object Reference
Look for parameters like id, user_id, order_number, or file.
Example URL:
https://hacklivly.com/orders?order_id=1001
2. Test for IDOR
- Change
order_id=1001 to order_id=1002.
- If the order details load, you’ve found IDOR.
3. Automate with Burp Suite
4. Escalate to Account Takeover
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Advanced IDOR Techniques
1. Mass Data Extraction
Use scripts to scrape thousands of IDs:
import requests
for id in range(1000, 2000):
r = requests.get(f"https://site.com/profile?user_id={id}")
print(r.text)
2. UUID Manipulation
3. Chaining with Other Vulns
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Defending Against IDOR
For Developers
Indirect Object References
Access Control Checks
Validate permissions on every request:
def get_order(request, order_id):
order = Order.objects.get(id=order_id)
if order.user != request.user:
raise PermissionDenied
Use UUIDs or Random Tokens
Rate Limiting
For Pentesters
- Test every endpoint that accepts an ID.
- Use Burp’s Compare feature to spot differences in responses.
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Tools for Finding IDOR
1. Burp Suite
- Intruder: Brute-force ID parameters.
- Scanner: Detect potential IDOR in requests.
2. Autorize (Burp Extension)
- Automatically test for IDOR by replaying requests with different user sessions.
3. OWASP ZAP
- Passive scanning for exposed object references.
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Practice Legally: Labs & Challenges
- PortSwigger Labs:
- Hack The Box:
- Machines like Access and Bart focus on IDOR.
- DVWA (Damn Vulnerable Web App):
- Practice in the Insecure Direct Object References module.
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What’s Next? Part 14: Insecure Deserialization – Turning Data into Disaster
Tomorrow, we’ll explore Insecure Deserialization—abusing how apps convert data into objects to execute code, crash systems, or steal secrets. Sneak peek:
import pickle
pickle.loads(malicious_data) # RCE achieved!
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Final Thoughts
IDOR is the low-hanging fruit of hacking—simple to exploit but devastating in impact. By adopting indirect references, strict access controls, and rigorous testing, you can slam the door on this lazy hacker’s favorite attack.
Remember: Security isn’t about making things hard for users; it’s about making things right for everyone.
Rocky out! ✌️
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P.S. If you’re loving this series, share it with your hacking crew! Let’s turn script kiddies into security guardians.
Discussion Question: What’s the craziest thing you’ve found via IDOR? I once accessed a CEO’s flight itinerary by incrementing an ID. 😅 Spill your stories below! 👇
