## 4 Resource Constrained IoT and Vulnerability to Cyber-Attacks
Some companies refrained from providing all resource information available within their IoT products: as a result, details of resources within some devices cover the above three resource aspects, whereas some only limit themselves to portray one to two of these aspects. Figure 3: IoT Prominent Application Domains. Generally, the IoT end devices have fewer resources as compared to their counterpart gateway devices. On top of that, the presented devices in Table 2 are usually constrained in-terms of one or more than one resource aspect, hence labeling them as not suitable for running resource-hungry security mechanisms such as the conventional IDS/IPS solutions. This in turn may allow malicious adversaries to exploit existing IoT vulnerabilities and launch devastating cyber-attacks. On top of that, most of the presented devices adopt communication technologies that are limited in terms of bandwidth usage, such as ZigBee, Bluetooth Low Energy (BLE), and LoRaWan, hence being exploitable to DDoS attacks that aim to saturate the available network bandwidth. On the other hand, some IoT devices  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Company** & **Product** & **IoT Device Type** & **Application Domains** & **Resources** \\ \hline \multirow{8}{*}{ \begin{tabular}{c} Milesight \\ (Xiamen, China) \\ \end{tabular}  } & \multirow{8}{*}{ \begin{tabular}{c} Indoor Ambience \\ Monitoring Sensor AM100 \\ Series \\ \end{tabular}  } & \multirow{8}{*}{End device} & & Power Source: \\  & & & Environment & (up to 32 h) \\  & & & & CPU:ARM Cortex-A7 \\  & & & & (528 MHz) \\  & & & & Memory: DDR4 RAM \\  & & & (256 MB) + eMMc Flash (4 GB) \\ \hline \multirow{8}{*}{ \begin{tabular}{c} MBobile Solutions Corp. \\ (New Taipei City, Taiwan) \\ \end{tabular}  } & \multirow{8}{*}{ \begin{tabular}{c} Gateway \\ \end{tabular}  } & \multirow{8}{*}{ \begin{tabular}{c} Water Supply \\ Management \\ \end{tabular}  } & \multirow{8}{*}{ \begin{tabular}{c} Power Source: \\ CPU: MediaTek 4X Arm \\ Cortex-A53 (2.0 GHz) \\ \end{tabular}  } \\  & & & Memory: RAM (4 GB) + \\  & & & & Flash (64 GB) \\ \hline \multirow{8}{*}{ \begin{tabular}{c} Four-Faith \\ (Xiamen, China) \\ \end{tabular}  } & \multirow{8}{*}{ \begin{tabular}{c} F-G100 Intelligent \\ Gateway \\ \end{tabular}  } & \multirow{8}{*}{ \begin{tabular}{c} Gateway \\ \end{tabular}  } & \multirow{8}{*}{ \begin{tabular}{c} Manufacturing \\ 32-bit communication \\ processor \\ \end{tabular}  } \\  & & & Memory: DDR3 (512 MB) \\  & & & & + Flash (32 MB) \\ \hline \multirow{8}{*}{ \begin{tabular}{c} Zoll \\ (Chelmsford, MA, USA) \\ \end{tabular}  } & \multirow{8}{*}{\ \begin{tabular}{c} Heart Failure \\ Management System \\ \end{tabular}  } & \multirow{8}{*}{End device} & \multirow{8}{*}{ \begin{tabular}{c} Power Source: \\ Redargeable Battery \\ (up to 18 H) \\ \end{tabular}  } \\  & & & & \\ \cline{1-1} \cline  
tend to have an abundant amount of resources to run heavy security solutions, such as the G350 Gateway by AMobile Solutions Corp (Taiwan)., but the presence of such an abundant amount of resources in an IoT gateway or end device might be limited, especially in deploymentson a large scale and over remote locations. An increasing number of sophisticated cyber-attacks have introduced significant concerns about the security of IoT-based systems. There are various types of attacks, including Prob, User to Root (U2R), Remote to Local (R2L), and DDoS attacks, that have a prominent impact on IoT-based systems. Such attacks are complex and have a large-scale impact, typically compromising thousands of IoT nodes. Table 3 presents a summary of the most prominent cyber-attacks at each layer over the three-layered IoT architecture [16], which can help in comprehending the imminent risk to IoT devices at each layer [60]. However, a recent survey showed that DDoS attacks have a dangerous and profound impact on the IoT ecosystem and are also frequently executed [61].