Capgo (capgo.app backend) before 12.127.5 contains an authorization flaw in the PATCH /private/role_bindings/:binding_id endpoint. The handler verifies that the newly assigned roles priority rank does not exceed the callers own rank, but — unlike the DELETE handler — it never checks the rank of the role currently bound to the target binding. An authenticated user holding the org_admin role (rank 90) can therefore change an org_super_admin binding (rank 95) to a lower-privileged role such as org_member (rank 75). Because the prevent_last_super_admin_binding_delete database trigger fires only BEFORE DELETE and not on UPDATE, an org_admin can demote every org_super_admin, leaving the organization with no super administrator. The issue is fixed in 12.127.5.
Weakness
The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.
Potential Mitigations
- Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) [REF-229] to enforce the roles at the appropriate boundaries.
- Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- For example, consider using authorization frameworks such as the JAAS Authorization Framework [REF-233] and the OWASP ESAPI Access Control feature [REF-45].
- For web applications, make sure that the access control mechanism is enforced correctly at the server side on every page. Users should not be able to access any unauthorized functionality or information by simply requesting direct access to that page.
- One way to do this is to ensure that all pages containing sensitive information are not cached, and that all such pages restrict access to requests that are accompanied by an active and authenticated session token associated with a user who has the required permissions to access that page.