# The Security Perspectives of Vehicular Networks: A Taxonomical Analysis of Attacks and Solutions
## 5 Open Research Problems  
VANETs are one of the concerning research domains as it is connected with IoTs and IoEs. The increasing number of vehicles, applications and sophisticated attack processes are making it hard to stabilize the security notions of VANETs. Therefore, with the technology progress, VANETs also require some futuristic developments for secure sustainability. In this section, we discuss some open research problems in a multi-dimensional way as future directions. * _Dynamic topology:_ Dynamic topology is an obvious feature of VANETs. When a vehicle sends a message, it passes through several intermediate nodes. The maliciousness of those nodes is always a question due to the ad hoc-ness. Therefore, research must be carried out to map these dynamic topologies in some directed acyclic graph and to compute some reputation system over it depending upon the past behavior or trust score. Another considerable aspect is that we can also try to use distributed ledgers for the transparency of the system transactions in this dynamic topology. * _Real-time constraints:_ The mobility of vehicular networks always has been a challenging issue. The real-time data monitoring, prediction of anomalies with high accuracy, and low false rates always have attracted the research community. Various machine learning and deep learning methods exist for these; however, we should explore more for collaborative learning or federated learning to gather the attack knowledge from the environment adaptive. This would help to detect the zero-day vulnerabilities in VANETs. As VANETs majorly use Dedicated Short-Range Communication (DSRC), the novel futuristic methods must support the short range communication maintaining the QoS of the networks. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{**Sr. No.**} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \\ \hline
1 & [PERSON] et al. (2017) [131] & Yes & No & No & No & No & No & No & Yes \\ \hline
2 & [PERSON] et al. (2017) [55] & Yes & Yes & No & No & No & No & No & Yes \\ \hline
3 & [PERSON] et al. (2017) [132] & Yes & Yes & No & No & No & No & No & No \\ \hline
4 & [PERSON] et al. (2018) [133] & Yes & Yes & Yes & Yes & No & No & No & No \\ \hline
5 & [PERSON] et al. (2018) [89] & Yes & Yes & Yes & Yes & Yes & Yes & Yes & No & Yes \\ \hline
6 & [PERSON] et al. (2018) [134] & Yes & No & No & No & No & No & No & No \\ \hline
7 & [PERSON] et al. (2019) [28] & Yes & No & Yes & Yes & Yes & Yes & No & Yes \\ \hline
8 & [PERSON] et al. (2019) [63] & Yes & Yes & Yes & Yes & No & No & No & Yes \\ \hline
9 & [PERSON] et al. (2020) [41] & Yes & Yes & Yes & Yes & Yes & No & No & No & No \\ \hline
11 & Present survey & Yes & Yes & Yes & Yes & Yes & Yes & Yes & Yes & Yes \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Comparison of various related studies in the timeline* _Privacy_: Maintaining the privacy of user information is also an important research area. In today's VANETs or ITS, multimedia transmission is another issue. Users always prefer the seamless multimedia data transfer while moving from one place to another. These multimedia are controlled and stored by various clouds and service providers, and therefore, cloud security must be enhanced. On the other way, VANET security can also affect the cloud security. In both the cases, users' privacy must be protected. For example, the GPS-based location in taxi services must not unnecessarily reveal the user's travel behavior to a third party. The information that is sensitive and requires confidentiality, if leaked, may impact organizations by losing its credibility. Even users' personal information stored on a device from which multimedia is getting transferred using a VANET may be misused for financial frauds.