## 2 Related Work
### Man-In-The-Middle Attacks for VANET  
Recently, a significant research effort is being carried out to achieve security and privacy in VANET. [PERSON] et al. [16] were the pioneers to explore this area where they highlighted several security challenges in VANET. For instance, they argued that privacy preservation of vehicular users during highly mobile environment is extremely important. [PERSON] et al. [17] presented various security requirements in their study, i.e., authentication, integrity, availability, confidentiality, and non-repudiation to solve above issues. On the other hand, different studies identified attacker models which were classified into two classes: high and low level [18; 19]. However, these models are limited in scope and does not consider different strategies of these attackers. Similarly, several attacks were identified and classified according to security requirements [20; 21; 22; 23; 24]. For instance, DoS, MITM and eavesdropping attacks were major identified attacks. On the other hand, there are some studies which focused on performing risk assessment of various risks in VANET. For instance, [PERSON] et al. provided a context-based risk assessment framework where various attacks along with their risk in VANET are identified [10]. Further, the attacks are categorized according to three classes, i.e., critical, major and minor. According to this study, MITM attacks are critical and have severe impact on VANET. [PERSON] et al. analyzed the impact of black hole attacks on two routing protocols Ad Hoc On-Demand Distance Vector (AODV) and Ad Hoc On-Demand Multipath Distance Vector (AOMDV) in the context of VANET [25]. The findings showed that MITM attacker performing black hole attack affects the performance of the routing protocols in terms of throughput. Further, [PERSON] et al. proposed a solution to cater black holes by broadcasting unicast packets and integrating trust within AOMDV [26]. However, how the routing protocols will behave for urban and rural areas are missing from these studies. [PERSON] et al. studied the performance of wide range of routing protocols in VANET under black hole attacks [27]. The authors evaluated AODV, Optimized Link State Routing (OLSR), Dynamic Source Routing (DSR) and Destination-Sequenced Distance-Vector (DSDV) protocols for MITM attackers performing black hole attack for realistic network, concluding that the black hole attacks have severe impact on successful packet delivery in the network. Further, [PERSON] et al. studied the affect of black hole attacks for different routing protocols in VANET including AODV and Zone Routing Protocol (ZRP) [28]. However, the above studies consider routing protocols which are used mainly for traditional Mobile Ad-hoc Networks (MANET) environment and these routing protocols can not be used in VANET due to large-scale and high mobility of the vehicles. [PERSON] et al. adopted a different approach to mitigate the impact of black-hole attacks in VANET where every vehicle maintains a trust routing table for neighbors [29]. Further, in case no neighbor is present near the legitimate vehicle, then the messages are exchanged with RSU to avoid any miscommunication within the network. However, there are three main drawbacks of this study. Firstly, this solution requires the presence of RSU for black-hole detection, which cannot be ensured in every scenario of VANET. Secondly, this solution always assume that the vehicles have low mobility. Thirdly, how this approach will behave in a rural scenario is not addressed by the authors. To identify MITM attacks with dropping ability, [PERSON] et al. presented a study using quality control charts where abnormal activity is identified by continuously monitoring the network [30]. In the proposed method, two limits are identified for packet loses using statistical process control. This is an efficient technique to identify MITM attacks performing black-hole as the network is continuously monitored in a real-time environment. [PERSON] et al.