# Security Threats in Intelligent Transportation Systems and Their Risk Levels
## 3 Risk Analysis Study
### Risk Analysis Study in ITSs
#### 3.1.3 Target of Evaluation (ToE)  
**Assumptions**  
We will consider the following assumptions:  
* There is a passenger in the vehicle;
* Threats require between one day and one week to be identified and developed;
* Attackers are experts.  
**System assets**  
Taking into account the last assumption, an ITS system is composed of logical assets, physical assets and human assets.  
As physical assets, we enumerate:  
Vehicles: vehicles are essential entities of VANET that can play different important roles in the network: (1) generate critical data (information about traffic state), (2) route data to other vehicles and (3) store critical data (user identity, alert messages). In VANET, each vehicle is composed of: (1) sensors, (2) application utility (AU) and (3) on board unit (OBU). The sensors receive information on the environment and the AU generates messages based on collected information. These messages are shared with neighbors via the OBU. The compromise of vehicles or other ITS components will cause modification of messages as well as routing operations, leading to the propagation of compromised messages in the system.  
Road Side Unit (RSU): an RSU, as a static component, is more vulnerable to cyberattacks, and constitutes one of the privileged passages for attackers to enter the VANET. An RSU serves as a link between vehicles and infrastructure (V2I). The important elements of the RSU are its hardware, its operating system (OS) and the software embedded in the OS. This software is used to interact with vehicles and infrastructure. If the RSU incurs a risk, the data stored in the RSU is compromised, and communication with the infrastructure is not secured.  
To these physical assets, we associate these logical assets:  
Shared Data: Important messages are communicated and shared between different vehicles and adjacent RSUs. Since these messages can be vital information, such as a crash warning, or critical information, such as private user data (e.g., ID and location), the security and confidentiality of the data need to be ensured in terms of confidentiality, integrity and availability ([PERSON] et al., 2016).  
Network Communication Protocols: Once we have introduced the different nodes of the VANET and their security role, we should provide secure communication between them. This involves the following kinds of communication:  
* In-vehicle communication between sensors, AU and OBU via Controller Area Network (CAN),
* Communication between two vehicles (V2V), and
* Communication between vehicle and adjacent RSU (V2I).  
An insecure communication protocol will not guarantee the safe transmission of data between vehicular nodes in the network.  
For human assets:  
VANET User: Since VANET is built to ensure the safety and convenience of vehicle users, the most important asset of VANET is the user. The safety of the users and their identity security are critical. In addition, the privacy of the user is considered the primary concern of VANET users and must be ensured. If the user is compromised, for example by a social engineering attack, all their personal information is compromised and their vehicle is a point of vulnerability for the entire VANET system ([PERSON] et al., 2016).  
**Threat agents**  
In our analysis, we adhere to the four dimensions of threat agents defined in [PERSON] et al. (2012):  
* A threat agent with programmable radio transmitters/receivers.
* A valid ITS-S (node of a system)
* used as an attack proxy by a remote threat agent;
* providing false or misleading information;
* using programmable radio transmitters/receivers.