# Survey on Security Threats in Agricultural IoT and Smart Farming
## 3 Security Threats in Modern Agriculture
### IoT Vulnerabilities, Risks and Threats in Agriculture  
The main cybersecurity threats were extensively presented in the previous subsection. Every and each of these threats are also applicable to IoT technologies and consist a threat for the associated agricultural applications. In the following paragraphs, a more detailed and focused survey on the IoT domain and its threats in agriculture is presented. IoT technologies are widely adopted by agricultural stakeholders in every part of the world and in every phase from production to supply chain. Thus, their role and their susceptibilities and risk are of high importance and worthy of study.  
IoT technology is consisted of four major systems, which render the communication between two endpoints (nodes) feasible. An IoT system technology is composed of: (i) the sensing technology; (ii) IoT gateways; (iii) cloud server/data storage and (iv) remote control using mobile applications.  
Current along with new risks and vulnerabilities come along with new as well as older types and architectures of IoT systems in agriculture. Such vulnerabilities can be attributed to hardware and software issues of the IoT devices, communication protocols, as well as data storage and processing solutions (e.g., in cloud infrastructures, data centers and smartphones) [2; 11]. A brief but accurate categorization of the main causes of low security in IoT include, according to [2; 104; 105], the following:  
* Unpatched firmware and/or extended use of default passwords, which allow for compromising the devices within an IoT network;
* Limited computational resources of smart devices, which hinders the implementation of complex cryptographic algorithms, due to the efforts of vendors to reduce the costs of their products in a competitive environment;
* Vulnerabilities in the communication protocols used by smart devices (e.g., ZigBee, Bluetooth);
* Low security level of the old version of the Wi-Fi Protected Access (WPA) protocol, which is still used in many cases;
* Search engines that can be used for executing passive vulnerability detection;
* The danger of organizing millions of smart devices in a powerful botnet (e.g., Mirai), due to the relatively easy detection of vulnerabilities by means of internet scanning;
* General lack of attention to the security of smart devices.  
Concisely, the overall lack of security of smart devices is caused by the general absence of standards or mandatory official recommendations for the security of IoT. The lack of legislative acts that regulate the responsibility between the manufacturer, the seller and the client, as well as the existence of a diversity of devices, combined with the need for costs savings, jointly affect the security of IoT [2; 78].  
Finally, IoT vulnerabilities, risks and threats can be classified using several different criteria. These threats apply to IoT applications in general, also including the agricultural domain. Firstly, there are two main classification categories of security threats in IoT applications in the agricultural sector, namely: (i) internal vs. external threats; (ii) passive vs. active threats [79]. Another interesting classification of threats for IoT follows a layer-based approach. [PERSON] et al. [22] propose that each of the following layers combines diverse technologies that bring a number of possible vulnerability issues, breaches and/or security threats. The architecture of IoT depends upon five distinct layers: (i) the application layer; (ii) the middleware layer; (iii) the internet layer, (iv) the access gateway layer and (v) the edge technology layer. Taking into account the layered architecture of a typical IoT system and the diverse technologies that it adopts, there is a significant number of possible vulnerability issues, security breaches and threats, which can result in major issues and/or problems for the organizations into the agriculture domain. Possible attacks on each layer of a typical IoT system are classified as depicted in Table 3