Anyway, my workaround for now:
- config.OpenWebif.auth=true in enigma settings
- reverse proxy access to OpenWebif using nginx, while embedding credentials:
proxy_set_header Authorization "Basic STR" where STR is base64 encoded root:box_password string
This way I can control access in a proper way, using either firewall rules or fully fledged HTTP auth solution, instead of half-baked and incorrect hack forced by OpenWebif.