## 1 Introduction
\begin{table}
\begin{tabular}{p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \hline
**Cyberattack** & **Year** & **Target** & **Description** \\ \hline Stuxnet & 2010 & ICS/SCADA & It was against Iranian nuclear centrifuges, a real example of a spectacular cyberattack, propagated as powerful and structured malware capable of infiltrating industrial programmable logic controllers that electrically control nuclear centrifuges. \\ ShaMoon & 2012 & ICS/SCADA & It occurred against the Saudi Arabia oil companies. \\ BlackEnergy & 2015 & Smart Grid & It happened against the Ukrainian smart grid, Germany in 2014, another example which allowed the deletion of data, the destruction of hard drives and the takeover of infected equipment. Ukraine’s power central was unavailable through coordinated DDoS cyberattacks. \\ Mirai & 2016 & IoT Object & It was aimed at connected objects CCTV cameras. \\ WannaCry & 2017 & CPS/Healthcare & It was performed against hospitals in 2017. \\  & & & Supply chain attack started in March 2020, carried out through an update compromise of Orion management and supervision platform. Among the victims: Governmental institutions, Microsoft, FireEye, Palo Alto Networks, Malwarebytes and Mimecast. Which shows that the targets are big security companies as well. \\ Hospital & 2021 & CPS/Healthcare & In February 16 th, 2021, Oloran-Sainte-Marie France hospital victim of mansome cyberattack, which information system was paralyzed, none application works and neither external or internal network works. \\  & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The famous cyberattacks in the history targeted critical cyber infrastructure. subject to devastating and dramatic cyberattacks if cyber security requirements are not taken into consideration. Wherefore, protecting IoT-based critical cyber infrastructures from cyberattacks is essential. Herein, we answer the following relevant questions:  
* Who are the targets? * Who are the cyber attackers? * How do they attack? * How can we protect critical cyber infrastructures? The primary contributions of this paper are summarized as follows:  
* We provide a critical view of the most recent cybersecurity issues for IoT-based critical infrastructures. * We discuss probable cyber threats and cyber vulnerabilities, followed by the main exploitation strategies adopted by cyber criminals. In addition, we provide an in-depth taxonomy of cyberattacks that may affect IoT-based critical cyber infrastructures. * Finally, we present security requirements and some realistic recommendations and best practices to enhance cybersecurity solutions. The rest of the paper is organized as follows: Section 2 describes smart health and industrial control system as a critical infrastructure, through the presentation of the main characteristics and functions. The architecture layers are discussed in this section as well. Section 3 surveys the different studies about security issues and their proposed solutions. Section 4 presents the most important assets of cyber physical system, describes in detail cyber threats, cyber vulnerabilities, including exploitation strategies, and provides a taxonomy in-depth of cyberattacks affecting IoT-based critical infrastructure, followed by the specific sources behind cyber threats. CPS security requirements are also depicted in this section. In Section 5, we present some realistic cybersecurity guidelines. Finally, we conclude the paper and suggest some future developments in the last section.