## 2 Background and Related Work
### Security for SOAs in Other Industries  
In addition to the automotive domain and the medical field, there are other domains in the CPS area addressing SOAs and security.  
[PERSON] et al. [48] present a cyber-security survey in the field of smart grids and discuss existing challenges. The authors classify 15 cyberattack techniques (e.g., traffic analysis, Denial of Service (DoS) or privacy violation) based on an attacking cycle typ  
Figure 3: Intrusion Detection Prevention System (IDPS) Architecture proposed by [PERSON] et al. [45].  
ically used by malicious attackers (reconnaissance, scanning, exploitation, maintaining access). Furthermore, they explain three security categories (network security, cryptography for data security and device security) to map 25 known attacks to possible countermeasures. In addition, they discuss different challenges of heterogeneous systems (e.g., smart grids) due to various network protocols or limited hardware resources. The devices are mainly trimmed for low-power consumption and therefore not able to support computing-intensive security mechanisms. Another challenge is the distributed environment with different applications, domains (e.g., generation, transmission, customer, service provider) and security requirements.  
[PERSON] et al. [49] present a comprehensive survey on Supervisory Control and Data Acquisition (SCADA) systems with a focus on security. First, they give an overview about established SCADA communication protocols, which is followed by a list of reported incidents. In the years 2000-2018, 15 attacks of high impact were reported. A well-known example is the _Stuxnet_ worm in 2010, which targeted the sabotage of a uranium enrichment facility. Moreover, the authors discuss fundamental lacks of security (e.g., missing authentication or integrity) in SCADA protocols and provide a summary of eight published IDS approaches. Five of them are based on the traffic classification detection technique, which processes network flows. Two of eight approaches are based on a system variable inspection, which determines correlations of physical sensor values in different system states or conducts a critical state analysis. One approach uses a multilayer security framework consisting of IDS by using physical and cyber features and firewalls with predefined whitelists for filtering network packets. Moreover, the survey includes further overviews about specific security solutions for protocols such as Distributed Network Protocol 3 (DNP3), PROeess Field NET (PROFINET), EtherCAT and IEC 61850. As a conclusion, the authors mention open research problems and challenges such as the introduction of Software-defined Networking (SDN), which provides more networks with flexibility; however, adapted security mechanism are needed.  
[PERSON] et al. [50] mention a related challenge through the deployment of SOA-based SCADA. The corresponding services are connected by Ethernet and TCP/Internet Protocol (IP) protocols to ensure a compatibility to existing services on the web. As a result, the risk for potential cyberattacks increases due to these well-known protocols. Furthermore, the distributed architecture design of such systems across local system boundaries leads to changed security concepts compared to field networks.