Insecure Direct Object References

Insecure Direct Object References occur when an application provides direct access to objects based on user-supplied input. As a result of this vulnerability attackers can bypass authorization and access resources in the system directly, for example database records or files. - OWASP

Summary

• Tools
• Exploit
  • IDOR Tips
• Examples
• References

Tools

• BApp Store > Authz
• BApp Store > AuthMatrix
• BApp Store > Autorize

Exploit

The value of a parameter is used directly to retrieve a database record.

http://foo.bar/somepage?invoice=12345

The value of a parameter is used directly to perform an operation in the system

http://foo.bar/changepassword?user=someuser

The value of a parameter is used directly to retrieve a file system resource

http://foo.bar/showImage?img=img00011

The value of a parameter is used directly to access application functionality

http://foo.bar/accessPage?menuitem=12

IDOR Tips

• Change the HTTP request: POST → PUT
• Change the content type: XML → JSON
• Increment/decrement numerical values (1,2,3,..)
• GUID/UUID might be weak
• Transform numerical values to arrays: {"id":19} → {"id":[19]}

Examples

• HackerOne - IDOR to view User Order Information - meals
• HackerOne - IDOR on HackerOne Feedback Review - japz

Labs

• Insecure direct object references

References

• OWASP - Testing for Insecure Direct Object References (OTG-AUTHZ-004)
• OWASP - Insecure Direct Object Reference Prevention Cheat Sheet
• BUGCROWD - How-To: Find IDOR (Insecure Direct Object Reference) Vulnerabilities for large bounty rewards - Sam Houton
• IDOR tweet as any user by kedrisec
• Manipulation of ETH balance
• Viewing private Airbnb Messages
• Hunting Insecure Direct Object Reference Vulnerabilities for Fun and Profit (PART-1) - Mohammed Abdul Raheem - Feb 2, 2018