# Security Challenges in Industry 4.0 PLC Systems
## 3 Risk Sources in OT Systems
### Software in Network Systems
#### 3.3.1 SCADA Systems  
Supervisory Control and Data Acquisition (SCADA) are IT systems aimed at supervising the course of the technological or production process. The specific functions of the production process supervision systems include collecting current data from measuring elements, visualizing data, controlling the production process, alerting errors or deviations as well as data archiving using comprehensive databases. SCADA systems play a superior role in relation to the PLC controllers and other devices directly influencing the production process. PLCs either collect information directly from sensors or use devices that collect such data. Thus, via the controller, the data go to a computer system such as SCADA, where it is processed, visualized and archived. Process control system operators can set process parameters and often control the process in manual or emergency mode. It is also worth noting that SCADA systems are scalable and can process thousands of input variables, depending on the complexity and scope of the technology. Industrial supervision, control and data acquisition systems can communicate with the control layer devices via special industrial buses or networks in standards such as RS-232, RS-485, CAN or Profibus. However, more often, due to lower costs, classic computer networks based on Ethernet are used. As in the case of PLC controllers (Section 3.2.3), one of the weakest points in SCADA are the protocols used for communication between individual system components. Their choice in the case of communication between the controller and the SCADA system depends mainly on the choice of the controller manufacturer and the possibilities offered. Designers of non-dedicated SCADA systems most often provide a full range of connection options and data acquisition from the controller. Communication protocols such as Modbus or Profinet significantly facilitate the software of data transmission and reception; however, they do not provide sufficient security for such a connection in order to minimize the risk of a cyber-attack. By taking advantage of weaknesses, such as the lack of a properly complex authentication system, the lack of a unique key for communication or ensuring confidentiality and data integrity control, a hacker attack may damage or cause malfunction of the SCADA system. The following are some examples of programs used to launch attacks: worms, viruses and Trojans:  
**Stuxnet**  
Stuxnet is a Windows-based computer worm that mainly targets devices using the Siemens WinCC SCADA system. It was detected in 2010 for the first time, and it is the first known worm used to spy on and make changes to the software of industrial installations. According to an independent Symantec report [87], Stuxnet is one of the most comprehensive cybersecurity threats facing industrial automation networks today. The Stuxnet worm mainly selects specific control systems related to services essential for the operation of the state (e.g., gas pipeline networks and power plants). The main purpose of this malware is to sabotage the production process by making changes in the PLC algorithms and hiding these changes from the SCADA system. Stuxnet has been used most widely in Iran, and despite its discovery in 2010, there are indications that the worm may have existed more than a year earlier and would have been undetected for that period of time. The complexity of the threat posed by Stuxnet has significantly influenced the perception of cybersecurity of industrial systems. Despite the fact that this worm mainly targets networks based on Siemens controllers, it is not difficult to imagine its modifications aimed at infecting third-party controllers or other industrial automation equipment in general. **Industroyer**  
Industroyer is a malware of the framework, which is considered to be the main tool used during the attack on a Ukrainian power plant in 2016. As a result of this attack, approximately one million people were deprived of electricity for six hours.