OpenRemote has Improper Access Control via updateUserRealmRoles function

Summary

A user who has write:admin in one Keycloak realm can call the Manager API to update Keycloak realm roles for users in another realm, including master. The handler uses the {realm} path segment when talking to the identity provider but does not check that the caller may administer that realm. This could result in a privilege escalation to master realm administrator if the attacker controls any user in master realm.

Details

In manager/src/main/java/org/openremote/manager/security/UserResourceImpl.java, there is no check to validate if the caller should be able to administer a realm they're trying to update.

    @Override
    public void updateUserRealmRoles(RequestParams requestParams, String realm, String userId, String[] roles) {
        try {
            identityService.getIdentityProvider().updateUserRealmRoles(
                realm,
                userId,
                roles);
        } catch (ClientErrorException ex) {
            ex.printStackTrace(System.out);
            throw new WebApplicationException(ex.getCause(), ex.getResponse().getStatus());
        } catch (Exception ex) {
            throw new WebApplicationException(ex);
        }
    }

PoC

1. Create a new Keycloak realm other than master. Add a user and grant that user the OpenRemote client role write:admin. Remember the realm name (call it NEW_REALM).
2. In Keycloak realm master, pick a low-privilege user (no admin realm role). Copy that user’s UUID (<master-user-uuid>).
3. Authenticate as the user from step 1 and obtain a Bearer access token (<token>) for NEW_REALM.
4. Replace placeholders and run:

curl -k -X PUT "https://<host>/api/<NEW_REALM>/user/master/userRealmRoles/<master-user-uuid>" \
  -H "Authorization: Bearer <token>" \
  -H "Content-Type: application/json" \
  -d '["admin"]'

5. In the Keycloak Admin Console, realm master, that user, Role mapping. Confirm the admin realm role is assigned.

Impact

An attacker with the OpenRemote client role write:admin in any realm can call this API with {realm} set to another realm (for example master) and change Keycloak realm roles for users there. That can grant admin on master to a user UUID they target, which gives Keycloak administrator access for the master realm.