/django-access-review

name: django-access-review
description: 'Django access control and IDOR security review. Use when reviewing Django views, DRF viewsets, ORM queries, or any Python/Django code handling user authorization. Trigger keywords: "IDOR", "access control", "authorization", "Django permissions", "object permissions", "tenant isolation", "broken access".'
allowed-tools: Read Grep Glob Bash Task
license: LICENSE

<!-- Reference material based on OWASP Cheat Sheet Series (CC BY-SA 4.0) https://cheatsheetseries.owasp.org/ -->

Django Access Control & IDOR Review

Find access control vulnerabilities by investigating how the codebase answers one question:

**Can User A access, modify, or delete User B's data?**

Philosophy: Investigation Over Pattern Matching

Do NOT scan for predefined vulnerable patterns. Instead:

1. **Understand** how authorization works in THIS codebase 2. **Ask questions** about specific data flows 3. **Trace code** to find where (or if) access checks happen 4. **Report** only what you've confirmed through investigation

Every codebase implements authorization differently. Your job is to understand this specific implementation, then find gaps.

---

Phase 1: Understand the Authorization Model

Before looking for bugs, answer these questions about the codebase:

How is authorization enforced?

Research the codebase to find:

□ Where are permission checks implemented?
  - Decorators? (@login_required, @permission_required, custom?)
  - Middleware? (TenantMiddleware, AuthorizationMiddleware?)
  - Base classes? (BaseAPIView, TenantScopedViewSet?)
  - Permission classes? (DRF permission_classes?)
  - Custom mixins? (OwnershipMixin, TenantMixin?)

□ How are queries scoped?
  - Custom managers? (TenantManager, UserScopedManager?)
  - get_queryset() overrides?
  - Middleware that sets query context?

□ What's the ownership model?
  - Single user ownership? (document.owner_id)
  - Organization/tenant ownership? (document.organization_id)
  - Hierarchical? (org -> team -> user -> resource)
  - Role-based within context? (org admin vs member)

Investigation commands

# Find how auth is typically done
grep -rn "permission_classes\|@login_required\|@permission_required" --include="*.py" | head -20

# Find base classes that views inherit from
grep -rn "class Base.*View\|class.*Mixin.*:" --include="*.py" | head -20

# Find custom managers
grep -rn "class.*Manager\|def get_queryset" --include="*.py" | head -20

# Find ownership fields on models
grep -rn "owner\|user_id\|organization\|tenant" --include="models.py" | head -30

**Do not proceed until you understand the authorization model.**

---

Phase 2: Map the Attack Surface

Identify endpoints that handle user-specific data:

What resources exist?

□ What models contain user data?
□ Which have ownership fields (owner_id, user_id, organization_id)?
□ Which are accessed via ID in URLs or request bodies?

What operations are exposed?

For each resource, map:

• List endpoints - what data is returned?
• Detail/retrieve endpoints - how is the object fetched?
• Create endpoints - who sets the owner?
• Update endpoints - can users modify others' data?
• Delete endpoints - can users delete others' data?
• Custom actions - what do they access?

---

Phase 3: Ask Questions and Investigate

For each endpoint that handles user data, ask:

The Core Question

**"If I'm User A and I know the ID of User B's resource, can I access it?"**

Trace the code to answer this:

1. Where does the resource ID enter the system?
   - URL path: /api/documents/{id}/
   - Query param: ?document_id=123
   - Request body: {"document_id": 123}

2. Where is that ID used to fetch data?
   - Find the ORM query or database call

3. Between (1) and (2), what checks exist?
   - Is the query scoped to current user?
   - Is there an explicit ownership check?
   - Is there a permission check on the object?
   - Does a base class or mixin enforce access?

4. If you can't find a check, is there one you missed?
   - Check parent classes
   - Check middleware
   - Check managers
   - Check decorators at URL level

Follow-Up Questions

□ For list endpoints: Does the query filter to user's data, or return everything?

□ For create endpoints: Who sets the owner - the server or the request?

□ For bulk operations: Are they scoped to user's data?

□ For related resources: If I can access a document, can I access its comments?
  What if the document belongs to someone else?

□ For tenant/org resources: Can User in Org A access Org B's data by changing
  the org_id in the URL?

---

Phase 4: Trace Specific Flows

Pick a concrete endpoint and trace it completely.

Example Investigation

Endpoint: GET /api/documents/{pk}/

1. Find the view handling this URL
   → DocumentViewSet.retrieve() in api/views.py

2. Check what DocumentViewSet inherits from
   → class DocumentViewSet(viewsets.ModelViewSet)
   → No custom base class with authorization

3. Check permission_classes
   → permission_classes = [IsAuthenticated]
   → Only checks login, not ownership

4. Check get_queryset()
   → def get_queryset(self):
   →     return Document.objects.all()
   → Returns ALL documents!

5. Check for has_object_permission()
   → Not implemented

6. Check retrieve() method
   → Uses default, which calls get_object()
   → get_object() uses get_queryset(), which returns all

7. Conclusion: IDOR - Any authenticated user can access any document

What to look for when tracing

Potential gap indicators (investigate further, don't auto-flag):
- get_queryset() returns .all() or filters without user
- Direct Model.objects.get(pk=pk) without ownership in query
- ID comes from request body for sensitive operations
- Permission class checks auth but not ownership
- No has_object_permission() and queryset isn't scoped

Likely safe patterns (but verify the implementation):
- get_queryset() filters by request.user or user's