# 5G Support for Industrial IoT Applications--Challenges, Solutions, and Research Gaps
## 8 IoT Security in 5G
### General Security Considerations within 5G  
Since 5G was introduced, a huge emphasis is put on its benefits as an optimal telecommunication platform for IoT applications and systems. 5G meets such requirements related to IoT that can not be fulfilled before, in the terms of bitrate, latency, reliability, and many others. However, as general insufficiency of security in IoT systems remains unresolved, it is mandatory to discuss how security considerations have been taken into account in 5G in respect to IoT scenarios. Being a wireless communication network, a significant part of security schemes and solutions applied in 5G are adopted from other wireless technologies, but as it uses licensed spectrum, the main security concerns is inherited from legacy cellular networks, such as its ancestor, Long Term Evolution (LTE). It is also beneficial that fundamental technical improvements that aimed to enhance efficiency are valuable techniques against numerous security threats, such as Massive MIMO against eavesdropping. However, applying legacy security solutions, besides many others, plays only a minor role of the whole scheme, as security is intrinsically an integral part of the overall architecture. Therefore, it has flexible security scheme and methods by design to (i) deal with new requirements derived from huge number of possible use-cases where 5G will be utilized, (ii) support new trust models as well as new threat-handling models, and (iii) handle MMTC traffic and management -massive number of various types of connected devices. Before discussing concrete proposed solutions, it is worth reviewing what general considerations does 5G have regarding traditional CIA requirements of IoT security. Due to the separation of control and user planes, networking mechanisms are implemented in a different way than previous cellular networks: most functions are virtualized now, so they are purely software. Therefore, technologies, such as SDN and NFV, play a major role in implementing network elements and functions to provide the aforementioned high flexibility as well as network slicing. Using these technologies makes it possible to apply different approaches and techniques for each individual use case, thus adjusting 5G networks to specific criteria. On the other hand, all of these new solutions bring new security threats and challenges into 5G based systems [89]. Table 8 provides a summary of security challenges regarding technologies that 5G is build upon. Therefore, standards and related researches focus almost exclusively on solving these 5G specific issues, instead of use-case specific ones, i.e., CIA in an IIoT manner. \begin{table}
\begin{tabular}{p{85.4 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Layer** & **Threat type** & **Mitigation** \\ \hline \multirow{2}{*}{Physical} & Tampering & tamper-resistant packaging spread-spectrum techniques \\ \hline \multirow{3}{*}{Networking} & Denial of Service & active firewalls, passive monitoring (probing), traffic admission control, bi-directional link authentication encryption, authorization \\ \hline \multirow{3}{*}{Data processing} & Back door attack & properly configured firewalls on all system entry point educating employees to security awareness traffic monitoring malware detection \\ \hline \multirow{3}{*}{Application} & Client app. Comm. channel Integrity Modifications & anti-virus filtering proper authentication, authorization, integrity verification testing validation process planning and design Traceability \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Security threats in automation IoT and their possible mitigation [83]. The most important threats are well-known, such as the aforementioned DoS and man-in-the-middle attacks, where their main targets are SDN- and NFV-based elements, so the core parts of the network [90]. Although these are general 5G issues and not IoT-specific, it is still worth mentioning that the control plane in 5G relies upon cloud is basically operates as a cloud, thus general 5G threats can be considered as IoT related issues.