AllAboutBugBounty/IDOR.md

IDOR (Insecure Direct Object Reference)

Insecure direct object references (IDOR) are a type of access control vulnerability that arises when an application uses user-supplied input to access objects directly. The term IDOR was popularized by its appearance in the OWASP 2007 Top Ten. However, it is just one example of many access control implementation mistakes that can lead to access controls being circumvented. IDOR vulnerabilities are most commonly associated with horizontal privilege escalation, but they can also arise in relation to vertical privilege escalation.

1. Add parameters onto the endpoints for example, if there was

GET /api/v1/getuser
[...]

Try this to bypass

GET /api/v1/getuser?id=1234
[...]

2. HTTP Parameter pollution

POST /api/get_profile
[...]
user_id=hacker_id&user_id=victim_id

3. Add .json to the endpoint

GET /v2/GetData/1234
[...]

Try this to bypass

GET /v2/GetData/1234.json
[...]

4. Test on outdated API Versions

POST /v2/GetData
[...]
id=123

Try this to bypass

POST /v1/GetData
[...]
id=123

5. Wrap the ID with an array.

POST /api/get_profile
[...]
{"user_id":111}

Try this to bypass

POST /api/get_profile
[...]
{"id":[111]}

6. Wrap the ID with a JSON object

POST /api/get_profile
[...]
{"user_id":111}

Try this to bypass

POST /api/get_profile
[...]
{"user_id":{"user_id":111}}

7. JSON Parameter Pollution

POST /api/get_profile
[...]
{"user_id":"hacker_id","user_id":"victim_id"}

8. Try decode the ID, if the ID encoded using md5,base64,etc

GET /GetUser/dmljdGltQG1haWwuY29t
[...]

dmljdGltQG1haWwuY29t => victim@mail.com

9. If the website using graphql, try to find IDOR using graphql!

GET /graphql
[...]

GET /graphql.php?query=
[...]

10. MFLAC (Missing Function Level Access Control)

GET /admin/profile

Try this to bypass

GET /ADMIN/profile

Source: @swaysThinking and other medium writeup!