This Recommendation analyzes security threats to connected vehicles in two parts: threats against interfaces which are used to communicate between a vehicle and its external devices, and threats against external devices which communicate with the vehicle. This Recommendation specifies security requirements for such external interfaces and external devices with vehicle access capability in telecommunication network environments to address identified threats depending on types of access interfaces. Interfaces and external devices with vehicle access capability include remote keyless entry (RKE) system with smart key, diagnostic tool and wireless dongle using on-board diagnostic II (OBD-II) port, telematics control units with wireless communication devices and so on.