# Security Vulnerabilities in LPWANs--An Attack Vector Analysis for the IoT Ecosystem
## 1 Introduction
Narrowband IoT (NB-IoT) is an LTE-based protocol that has been designed to address the needs of very low data rate and low-power devices that need to connect to the Internet using standard mobile networks [20]. It can be operated in LTE or GSM under licensed frequency bands [21], which is a major drawback, due to the use of licensed spectrum, which increases considerably the operational cost (LTE frequency band for example, the price is over 500 million euro per MHz [22]). Mobile LPWA technologies, such as 5G -IoT and LTE-LPWA are still under development. It is anticipated that about 80 billion devices will be linked within a network, and 20.5 billion will be associated per user by 2030 [23; 24; 25]. The 5G network will be conceived to engage high data transfers and small packet transfers, that do not consume symbolic network signaling and power resources [26]. The reduction of energy consumption in 5G technologies can be accomplished by using green technologies and it can be capable of extensive connectivity and a high amount of data [27]. To make 5G-IoT less expensive over time, some solutions like large-scale manufacturing and common platforms optimization have been recommended [26]. LPWANs have been widely used in several IoT applications as the main communication technology [28]. This type of network is known for its low-power usability, long-range, low-cost, and high availability, being in use in several application domains, such as environmental monitoring for natural disaster detection [29], smart security [30], smart agriculture [31] and smart health [32]. This variety of application domains can work adequately on this technology. For example, in an e-Health IoT application, the body temperature or the blood pressure can be coded in small payloads and reported to Health Care centers, in a specific time interval (hours/days) [32]. However, if these communications are compromised, several high-risk attacks can be performed. In a scenario where a malicious  
Figure 2: Power/Bandwidth vs. Range in wireless communication Technologies. Adapted from [10]. agent interferes with the communications between the IoT devices and the Health Care centers, the user's health can be severely impacted. In other application domains, for example, in a bicycle sharing scenario, an attacker can compromise the location of a bicycle--by attacking the bicycle tracking system--to subtract/steal the bicycle from the system. Moreover, LPWAN technologies can lead to security issues that we aim to explore in this work. For instance, SigFox does not encrypt the transmitted frame (i.e., the encryption is done by the developer, in the application layer) [33]. In LoRaWAN, the join request is not encrypted in any way, which can lead to a possible eavesdropper that could gain information about the topology of the network [33]. Moreover, LPWAN technologies use, in general, symmetric-key cryptography in which, the end devices and the network, share the same secret key [28]. The main goal of this work is to provide a general overview of which LPWAN technologies are most used today, as well as, to address the core security gaps found in this type of technologies. After identifying its core vulnerabilities, defense strategies are put forward for each specific attack vector, to mitigate the risks that are directly related to each vector. Afterward, a general model for the IoT ecosystem is presented, making it possible to map the security vulnerabilities previously identified, and thus, making it easier to identify the critical attack vectors that can be exploited by malicious users. This paper provides a security analysis to the attack vectors regarding generic IoT application, given by the evolution (in the last 10 years) of the security issues regarding LPWANs and explore the most relevant state-of-the-art works (from the last three years) that address this topic. To attain this goal, the research methodology was divided into these three steps:  
1.