authz-bypass-hunter

Authorization Bypass Hunter

Purpose

Systematically identify authorization vulnerabilities: IDOR, privilege escalation, broken access control, missing permission checks, role confusion, and horizontal/vertical privilege escalation.

Focus Areas

• IDOR (Insecure Direct Object References): User-controllable IDs accessing other users' data
• Broken Object Level Authorization (BOLA): API endpoints not validating resource ownership
• Broken Function Level Authorization (BFLA): Admin functions accessible to regular users
• Missing Access Controls: Endpoints without any authorization checks
• Role/Permission Confusion: Inconsistent role checks across code paths
• JWT/Session Issues: Token manipulation, session fixation

Audit Checklist

1. Identify Authorization Entry Points

- API endpoints with resource IDs (/api/user/{id}, /api/order/{id})
- Query parameters (userId=, accountId=, orderId=)
- Request body fields controlling resource access
- File paths/names in requests
- GraphQL queries with object references

2. Check for Missing Checks

Look for patterns:
- Direct database queries without user filter
- Fetching resource by ID only (not ownership)
- Missing @authorize, @permission decorators
- Inconsistent middleware application

3. Verify Ownership Validation

VULNERABLE:
  order = Order.find(params[:id])  # No user check!

SECURE:
  order = current_user.orders.find(params[:id])  # Scoped to user

Output Format

When you find authorization issues, report as:

findings:
  - title: "IDOR in GET /api/users/{id}/profile"
    severity: high
    attack_scenario: "Authenticated user changes {id} parameter to access other users' profiles"
    preconditions: "Valid session required"
    reachability: auth_required
    impact: "Unauthorized access to PII of any user"
    confidence: high
    cwe_id: "CWE-639"
    affected_assets:
      - "/api/users/{id}/profile"
      - "src/controllers/user_controller.rs:42"
    taint_path: "request.params['id'] -> User.find(id) -> response"

Key Patterns to Hunt

Missing User Scope (Most Common)

// VULNERABLE - no ownership check
pub async fn get_order(id: i32) -> Order {
    Order::find(id).await
}

// SECURE - scoped to user
pub async fn get_order(user: User, id: i32) -> Order {
    Order::find_by_user(user.id, id).await
}

Inconsistent Role Checks

# VULNERABLE - role checked in UI but not API
@app.route('/admin/users')  # No @admin_required!
def list_users():
    return User.all()

Parameter Pollution

# If both accepted, which wins?
GET /api/profile?userId=1001&userId=1000

HTTP Method Bypass

GET /api/admin/users/1000 → 403 Forbidden
POST /api/admin/users/1000 → 200 OK  # Vulnerable!

Severity Guidelines

KYCo Integration

Register authorization bypass findings using the kyco CLI:

1. Check Active Project

kyco project list

2. Register Finding

kyco finding create \
  --title "IDOR in GET /api/users/{id}/profile" \
  --project PROJECT_ID \
  --severity high \
  --cwe CWE-639 \
  --attack-scenario "Authenticated user changes {id} parameter to access other users' profiles" \
  --impact "Unauthorized access to PII of any user" \
  --assets "/api/users/{id}/profile,src/controllers/user_controller.rs:42"

3. View in Kanban

kyco gui  # Opens GUI with Kanban board
kyco finding list --project PROJECT_ID  # CLI listing

Common CWE IDs for Authorization Issues

• CWE-639: Authorization Bypass Through User-Controlled Key (IDOR)
• CWE-862: Missing Authorization
• CWE-863: Incorrect Authorization
• CWE-284: Improper Access Control
• CWE-285: Improper Authorization