A Survey on Possible Attacks in Vehicular Ad Hoc Network

A Survey on Possible Attacks in Vehicular Ad Hoc Network Gabriel G. Kariuki [email protected] Abstract:-In this research a survey is conducted that looks into the architecture of VANETs and their areas of application. The architecture is broadly discussed in the introductory part, which also outlines the key role players. The paper also keenly focuses on the various security and privacy concerns that are experienced in the implementation of VANETs. Privacy and security issues found to affect VANET are based on integrity, confidentiality, availability, and reliability of data and information exchanged in VANETs. Attacks are major security concerns that are thoroughly surveyed in this work. Some of the means that attackers use in VANET include DoS attack, masquerade, eavesdropping, jamming, and others. Some of the popular means through which these attacks can be controlled include cryptographic means such as encryption. Other security measures that can be practiced to control the attacks include authentication and others that are broadly discussed in the paper. There is more to be done in the future to increase capabilities, security, and privacy of VANETs. Keywords: Vehicular Ad Hoc Network, Security, Privacy, Attack, Vehicle, Challenges  I. INTRODUCTION Vehicular ad hoc network (VANET) is a network implemented for vehicles. The network is made to allow for the vehicles while traveling at a relatively high speed to communicate among themselves. This network is developed from the Mobile Ad Hoc Network (MANET) technology, aiming at increasing security on the roads during travel and transit. MANETs provide spontaneous creation of a wireless network that is used in data exchange in a domain of vehicles [1][2]. Therefore, the main purpose of VANET can be identified to be inter-vehicle communication (IVC). Sensors are fitted into vehicles, and upon sensing each other, they create an infrastructure that connects cars as indicated in the image below. Fig 1: VATEN communication illustration [3]. As illustrated in the image above, VANETs are fitted with sensors and other components involved n sending and receiving signals in cars and on roadsides. As indicated in the image, three types of communication take place. These are the vehicle to vehicle (V2V) communication and Vehicle to roadside unity (V2I) communication. The third type is the cluster to cluster (C2C) communication. This type of communication takes place where the VANETs are divided into different clusters. Each cluster contains a given number of vehicles. Cunha et al. (2016) explains that VANETs are then integrated with vehicle mechanism that allows the vehicle to respond to communication signals automatically [3]. The roadside units represent all fixed structures that are near the roads, and in a position that can be easily or accidentally reached by the vehicle. Therefore, with VANET network integrated into vehicles, one can detect another in front, behind, or in a nearby distance. II. RELATED WORKS Thandil (2015) writes a survey on security and privacy in VANET [25]. According to the survey, one reason as to why authors should focus on these networks is the aspect of the great impact they have on road and traffic safety. This survey also looks into the major components of these networks that require special attention, which is the security and privacy. Therefore, the survey looks into many research works that have been undergone in the main of improving security and performance in VANET. The paper also looks into various researches that propose various solutions for enhancing security and performance in VANET [25]. In another work by Rivas et al. (2011), one can learn of various security issues in VANETs [24]. The major security issues looked at in this research include false information, data aggregation, privacy, and misbehaving nodes. The authors in this work looks into current issues in VANET. The research also looks into the challenges found in most areas that require privacy and anonymity in VANET along with mechanisms that can be applied in detection and eviction of nodes that misbehave. The authors also propose multiple solutions directed toward solving these issues. This paper proposes the use of public key infrastructure (PKI) and certificate revocation. It also discusses the use of anonymity group signatures and location privacy [24]. In another research by Qu et al. (2015), looks into vulnerabilities that can be found in VANET considering that it is an open network [10]. The authors then provide multiple solutions to the vulnerabilities identified. The authors also explain the basics of VANET, providing a basic classification of the attacks and security threats as well as challenges. Solutions to the challenges and security threats to VANETs identified in this research are explained. Also, there are certain standards that the VANETs should meet for them to qualify to be secure upon their deployments [10]. III. GENERAL SURVEY OF VANET How VANET Works The VANET network architecture has three primary components. They are the onbound unit (OBU), the Roadside Unit (RSU), and the blackhaul network. These three component work in two different ways, which may be used in classifying types of VANETs which are the V2V and the Vehicle to Infrastructure (V2I) networks. The VANET network, like most other networks, have architectures with layers [1][2][3]. They are the physical layer, the media access layer, the network layer, the transport layer, and the application layer. Below is a diagrammatic illustration of the VANET architecture. Fig 2 VANET Architecture [5]. As illustrated in the diagram above, before arriving at the development of VANET, concepts and architectural designs have to be borrowed from other more advanced networking architectures. However, Pathan (2016) explains that there are no significant differences between WANETs and MANETS [2]. The networks do not rely on infrastructure that is pre-existent. This implies that they do not use networking components such as routers, access points, or various components used in wired networks. In this case, each of the three components act as nodes for routing and forwarding data packets as well as the reception of the same [2]. A wireless mesh network (WMN) serve the purpose of interconnecting the nodes. Below is an illustration of wireless mesh network infrastructure. Fig 3: Wireless Mesh Network [4]. The above image illustrates cars in traffic. Every vehicle has a node or can be considered as the note, and when all the cars and the RSUs interconnect, WMNs are formed. The networks, however, work as Wi-Fi. When there are no two or more nodes to interconnect, the network is not formed. But, when in close range as illustrated in the image above, self-configuration takes place among the nodes and the networks are formed. These aspects make the network dynamic. The aspect of the networks being dynamic makes it sophisticated and complex to have centralized administrative control centers created, not even in the cloud as Bitam et al. (2015) illustrates [19]. It is considered complex to set this up on a network that is considered to be “on the fly”—anywhere, anytime. Hasrouny et al. (2017) [6] explains that wireless sensors, as used in networks are a group of spatially dispersed and dedicated sensors that are used in monitoring and recording aspects such as physical conditions in an environment [6][7]. The sensors collect the information, which then processed. For instance, the sensor helps cars notice other cars or infrastructure from a far distance, and as a result, they get to be able to respond adaptively to avoid any dangers that may occur. The VANETs are integrated with intelligence devices that send signals to other parts of the vehicle so that it can trigger response. Since vehicles act as network nodes and routers, the wireless sensor networks receive packets, and with the application of intelligence, the node can detect and connect to another node that away in between two hundred and three hundred meters [8]. Application Areas of VANET There are numerous areas of application of VANETs. First, they allow for triggering of some safety activities while driving such as braking. The driver may not be aware of another vehicle at a close range, but through the communication, an alert can be raised persuading the driver to act accordingly. Or, the vehicle can use the information to respond automatically. Also, with infrastructure that is not visible such as speed bumps being in place and drivers do not notice them, VANETs get to receive the signals and respond accordingly [11]. Zaidi et al. (2016) and that platooning is another area of application of VANETs [11]. In this case, vehicles get close to each other to inches Vehicles receive information on when to accelerate and when to decelerate. It is indeed hard for drivers of long trucks to notice what is behind them and therefore, the communication between the vehicles can be used in managing traffic. The use of VANET in the management of traffic information systems is expansive. They are used in providing real-time information about obstacles, traffic congestions, and other details that give drivers heads-up on the nature of roads in front or behind them. VANET is also very much helpful in the provision of road safety. Real-time communication help in detecting parts of the roads where there might be problems and therefore have any issue responded to immediately. Also, the real-time communication increased road safety by giving road status dissemination, giving warnings, and reduction of delays and speedups. In case of a rescue, emergency services can arrive fast because the incident can be reported fast through VANET [12]. Indeed, VANET provides an alternative of dialing an emergency number in case of road accidents. The network also makes it easy for highway patrol officers as they can detect any problems even from miles away provided that they are on the network. In the future, technology is working on information-driven transportation systems that are wirelessly connected. Indeed, engineers in different research and development industries have already launched driver-less truck prototypes. Self-driving vehicles will make great use of VANET. Indeed, driverless vehicles are already in place, to have their information. Examples of these innovation cases include the Uber’s self-driving trucks, as explained by Hawkins (2018) which have set a record of delivering freight in Arizona [13]. WAYMO, a car, and technology company in 2017 launched a self-driving car that is supported by Google networking technologies. Another Swedish Company recently launched an electronic carrier truck that can transport load for 120 miles on a single charge as explained by Davis (2017) [14]. These are examples of technologies that are effective when integrated with VANETs as they can make them more efficient. More about this integration is discussed in future works. IV. VANET SECURITY SURVEY In VANET, security is an important issue of concern. This is because breach of security leads to losses automatically. Indeed, human lives in most cases are dependent on secure systems. Any security issue in a system puts human life at stake. The major security concerns in VANETs does not only involve confidentiality, integrity, and availability. This is because none of them involve primarily involve the safety of human life. Developing and trusting on VANET to work on the read where fatal accidents can happen, requires of it to be secure in a way that it can have minimal chances of putting human life into risks [5][15][17]. Any communication being transmitted in the network need to be secured such that it cannot be hijacked and altered. Also, a potential attacker has to be denied any chanced of altering the data being transmitted. Nonetheless, a secure VANET system guarantees users that they can rely on it in determining the responsibility of a driver while maintaining their privacy. If the network is involved in exchanges information about a driver in a car, it has to be secured, and more importantly, it has to be delivered on time without delay. Speed is considered to be of great importance mainly because the systems move in relatively high speed and therefore, delay in transmission of information can automatically lead to accidents from the collision of vehicles [17][21][24]. In information systems, the term absolute security does not apply, but developers can work on ensuring that the security is strong enough to be sufficient or make it hard for an attacker to conduct any illegal activities on the network. However, to make the security sophisticated enough in VANETs is challenging. The considerations of severe consequences as described above are the major concerns that are put forth [6]. Another issue that creates a great challenge is the aspect of the network being highly dynamic, where a centralized control point cannot be created. The dynamic nature of the network is experienced as a result of frequent and instantaneous arrivals and departures that drivers do. Also, the period through which a vehicle stay in a network is short unless there is traffic congestion and the distance of travel is long [12][16]. Moreover, vehicles have varying speeds which makes them not keep short distances in roads that are less busy. Another concern is the aspect of high mobility on top of the dynamic nature of the network. The network implements wireless means of communication and vehicles connect to the networks automatically. This implies an attacker cannot struggle to join the network. Indeed, for an attacker targeting a certain vehicle, they only need to stalk it and keep a close distance between them. The aspect of an adversary joining anytime increases the vulnerability of the network. Attacks on VANETs can be classified into various categories such as the cryptographic attacks. Also, general network security issues and unique network challenges arise as a result of unique characteristics of VANETs [6] [9][17]. These characteristics include the ones mentioned above. They are high mobility, dynamic topology, short connection duration, frequent disconnections, and short range of connection. Security Requirements for VANET Access Control This type of security requirements allows for vehicles to function by the rules and should do what is required of them. Access control is implemented to ensure that the nodes act by the specification and authorization that is in place regarding access control accordingly [9]. Message Integrity Ensuring that packets being transmitted over a network retain their integrity is ensured through their aspect of arriving at the destination as they were from source without having any changes made to them during transit. Thus, the message has to be protected from alteration or falsification for it to arrive accurately [7][9]. Authentication According to Manvi and Tangade (2017) [7] there exist greedy drivers and adversaries whom through the implementation of VANETs can be greatly condensed by the mechanism of authentication. This can be done by ensuring that all messages being transmitted are received from actual nodes. But privacy concerns are increased basically because authentication requires of users share their credentials yet they would be doing it on an open network. However, authentication, which is found to be a great necessity can be facilitated through the provision of a property that can be used in verifying and certifying that indeed a member in the network is valid or not [7][12][15]. This can be used in verifying information such as the confirming that indeed a vehicle is in a position that it claims to be in. Privacy Privacy of data and messages remains a concern. The information involved in the communication between cars needed to be confirmed and ensured that it does not leak to unauthorized parties. The same case applies to third parties who should not have access to the systems or the information about the vehicles in the network. There should not be information leaked about a particular vehicle that can distinguish it from others. As such, no vehicle can be tracked down, and no personal privacy can be violated [6][7][17]. Also, the location of a vehicle cannot be detected by others on the network to enhance location privacy. Not even the present, but also the past and future locations should not be disclosed in the network. Message Confidentiality This involves the maintenance of private information in the systems. The message can only be shared among nodes, and still, it has to remain confidential. Authorities may not be able to enforce laws that violate personal privacy whatsoever [7] [17] [19]. Real-Time Guarantee VANETs should be at work at all times. This is because VANETs are applied in safety services, which as mentioned earlier, put the lives of people at stake. Therefore, the systems should be guaranteed to remain working at all times [17]. Message Non-Repudiation The sender of a signal can be easily identified, which is not required at this juncture. Thus, fellow persons on the network should be restricted from identifying such a person. It is only specific authorities such as traffic control officers should be approved to have identification details of say vehicle owners in a network. A vehicle can be identified from a message that it my send, which may be authenticated [17] [19]. Some of the security issues that result from the above characteristics include trust group formation, position detection and prevention, and management of certificates. Classification of Attacks Implementation of VANETs to some is a great milestone that is very much beneficial. Cars run on power that is regenerated and therefore their circuit is always on power so long as they are running. The cars can be installed with processors and computing devices, to create portable workstations in them. This can enable individuals to conduct their businesses and exchange information as they interact through the systems built in the cars. Attackers can have such computational power which can be sufficient for facilitating an attack on VANNET [21]. The attacks are not computationally intensive and are not feasible in a normal ad-hoc network. The unique nature of VANET equals unique vulnerabilities and different types of attacks. As explain in the research by Amoozadeh et al. (2015) and others, classifying them is important as it is helpful in allowing for their better understanding and formulation of approaches of resolving them [17]. One way of categorization of the threats and vulnerabilities is through cryptographic means which is easy and straight due to its similarity with traditional means. This approach comes up with categories of attack base in security requirements of a network. To it to be accurate, it tries to compromise. Major categories are threats and attacks on availability, integrity, and confidentiality. Others include threats and attacks on accountability and authentication [15][17]. Fig 3: Classification of threats and attacks on VANETs [23]. As observed in the chart above, each category of security category is faced with various threats and attacks that are different from those done on others. Attacks on confidentiality: Under confidentiality, attackers can eavesdrop, gather information, or analyze traffic. Eavesdropping is the act of secretly listening or tapping communication lines to get the content being transmitted without the consent of either the sender or the receiver. Traffic analysis, on the other hand, is the act of intercepting and examining messaged exchanged in a communication line with the aim of deducing the communication line being used. This technique can be applied even in encrypted messages because it does not necessarily require the attacker to decode a message [4][9]. Attacks on integrity: Under integrity, message suppression is the act of reducing the number of packets being exchanged in a communication line. Alteration is the act of changing the meaning of the original message. Fabrication, on the other hand, is sending false message or signal [17][19]. For example, in the context of a situation where VANET is implemented, an attacker can block some signals from being sent. This can make the driver cause accidents especially if he can be relying on the network to get alerts. Also, false information and inadequate information, having been caused by the attacker through fabrication and suppression respectively, can lead to a driver causing accidents [4][8][23]. Attacks on authentication and identification: In masquerade, attackers disguise themselves as other persons who cannot be suspected. For instance, an attacker can make their malicious signals resemble ones that are used in VANETs, which can make them fail to be suspected. Replay attack, also identified as playback attack involves the transmission of valid data through the VANET getting maliciously and fraudulently repeated in a loop or delayed [23]. The replay can happen to security attacks that target integrity, authorization, and identification. In GPS spoofing attack, the attacker may use a program in successfully masquerading a legit user or by use of false data. This helps the adversary gain illegitimate privileges on the network. In cases where VANETs are implemented, an adversary can use GPS spoofing in altering the flow of V2V, RSI, and C2C communications [9]. Attacks on Availability: Indeed, some adversaries can use position faking an attack by broadcasting false information. For the case of self-drive cars or cars whose drivers may be over-reliant on the vehicles’ driver support systems, the false information can lead to such vehicles getting into accidents. Tunneling attack, also known as DNS tunneling involved encoding data from another program or protocol in DNS queries and responses. This type of attack can be better described as the addition of more packets into the packets in transit. WNSs are usually faced with the problem of key/certificate replication. Considering that they are major components that makeup VANETs, they expose the network into a vulnerability that can lead to an attack on the system [19][20]. Replication involves capturing some nodes physically and collecting all crucial information from it. The attacker can then reprogram the node or even replicate it to produce a similar node that they can control themselves. The replications can then be used in eavesdropping. Other methods of attaching as illustrated in the chart include message tampering which is a method of attack where the adversary alters message before delivery. The attacker puts the data in a way that upon reaching its destination, the aftermath of its reception or the effects caused by the altered data may be of benefit to the adversaries. On the other hand, as explained by Hasbullah et al. (2010), denial of service (DoS) attack, also known as the distributed denial of service (DDoS) attack involves adversaries denying the legitimate users of networks from accessing services [9]. In the case of VANET, the attackers may hack the network making nodes fail to interconnect automatically. In DoS attack, the adversaries may not manage to cut off the whole network mainly because it is highly dynamic. But, they can deny implementation of services in some sections. Nonetheless, VANETs may be susceptible to jamming attacks. Jamming, also known as radio jamming involves disruption of radio frequency waves, which are also involved in wireless communication. Jamming is an exploit that is used in compromising a wireless environment [9]. It is part of DoS attack where it denies services to authorized and legitimate users of a network. Adversaries succeed in this through overwhelming the traffic with illegitimate or fake traffic. In VANET, adversaries can introduce many of the components that make up the VANET. Which can introduce signals that may be abnormal and confusing [10]. Packet ball or black hole attack is a practice used by adversaries in a meshed network. With VANETs being made of ad hoc networking, the ad hoc architecture introduces vulnerabilities to the system because this type of attack is specially designed against ad hoc networks. It is also a type of DoS attack where the router is attacked, and instead of relaying packets, it discards them. For the router or the node to arrive at this, the adversary introduces overloads of inappropriate packets into the router [9][23][24]. This makes it fail to differentiate between the legitimate packets and the fake ones. It gets compromised. In VANET, the nodes act as routers, and therefore adversaries may target the nodes. Broadcast tampering, also known as broadcast intrusion involves hijacking broadcast signals in wireless networks, radio, or television signals as well as satellite signals. The attacker can then redirect or divert the signals to areas without legitimate recipients or ones who do not need them. Also, the signals can be redirected to the wrong recipients, who may receive wrong information. Last but not the least, spamming and malware attack can also be introduced in the network. Countermeasures and Control Strategies There are various solution techniques as that can be applied in solving these security issues on VANETs as discussed in this section. These solutions include cryptographic ones, use of trust grouping frameworks, and implementation of ID-based security systems for user privacy [16]. Cryptographic Solutions According to the results of a comprehensive survey conducted in this paper, the table below is developed illustrating a type of cryptography related attack, the services that are targeted, and the cryptographic solutions that can be applied [2][4][5][23][25]. Type of Attack Targeted Service Cryptographic Solutions and Proposals Illegal Tracking Privacy Implementation of an ID-based system for user privacy Position faking Authentication Implementation of activity detection systems Brute force attack Confidentiality Use of public key schemes DoS Availability Implementation of signature-based access control and authentication [15] Illusion/Impersonation Authentication Use of trusted hardware modules Packets modification Integrity Application of integrity metrics in inspecting the delivered content Eavesdropping Confidentiality Heavily encrypting sensitive data Jamming Availability Apply pseudorandom frequency hopping Traffic Analysis Confidentiality Use of randomized traffic patterns Table 1: Attacks and their solution. V. CHALLENGES IN VANET There are a variety of challenges that are experienced upon implementation of VANET. These challenges include technical issues, security issues, an attacker on VANET and attackers in VANET as explained below. Technical Issues The network, as indicated earlier, is highly dynamic. Thus, high portability is experienced—where cars move from one network cluster to another. Consequently, the network topology and conditions of the channels change fast. These aspects make it extremely difficult to have the traffic managed through the network in an attempt to avoid congestion and collision in the network. Sensors communicate through exchanging electromagnetic waves, which are affected by environmental conditions while in transit. They get obstructed by other waves in the traffic, heat, physical obstacles, wind, and other conditions that make then fail to more appropriately. Thus, in the implementation of VANETs, environmental considerations should be carefully looked. Also, design and architecture of some VANETs may not be up to standards [20]. Since this is modern technology, there are no well-known security considerations put in place to control the design and architecture of VANETs. Security Issues Security is one of the greatest concern as far as VANET is concerned. Technical issues can result in security issues. Attacks are security issues as well. Thus, various issues that are in place about VANETs are interlinked and affect each other either directly or indirectly. Messages should be delivered safely and in optimum speed without delay since delays can cause a collision in the traffic. Various attach techniques identified in Table 1 can lead to failure or breakage of the network. Others identified in the same table can cause critical interference in the network, which can lead to the network failing to work appropriately. Indeed, some course that a network is in favor of adversaries [15][20][21]. Security Requirements Issues There are various security requirements discussed earlier which include privacy, authentication, real-time guarantee, among others. All these security requirements have to be satisfied before a VANET is considered efficient for use. These requirements play a very great role but designing and developing an architecture that satisfies them all is complex and challenging. Also, even after they are all in place and working, they need to be inspected of functionality regularly. If faults may be identified, it is hard to repair since the network does not have a control center, it is dynamic. But, as explained by Bayat et al. (2016), authentication has to be maintained, false messaging should be eliminated, non-repudiation should be maintained, and attacks should be kept away [15]. Attacks on VANET This type of attack involves both insider and outsider attack. An insider is an adversary within the network while an outsider is one who is without the network. Insider attackers are authenticated users. These attacks can either be active or passive. Active attacks are ones that are generated in signals whereas passive attackers are ones that only sense signals in a network. Malicious and rational activities must be conducted on the papers as well. However, malicious attackers do not enjoy any benefits after conducting attacks [7]. Their motives are solely to harm the functionality of the network. The rational attackers, however, gain personal benefits after the attack Attackers in VANET Attacks in VANET are facilitated by hijackers who hijack sessions easily after they establish connections. The hijackers only need to pose as authenticated users of the network for them to gain access. The driver whose network channel get hijacked can have their privacy exposed, which by itself is a security issue [7][9][10]. VI. CONCLUSION VANET technology has not been administered vastly. However, there have been numerous researches that have been conducted, and most of them have identified that VANET is faced with great challenges that are caused by its unique features. Security and privacy issues are the basic issues along with an inability to cope with or keep away attackers. Attackers can use various methods of attack that are vastly discussed in the paper. However, Table 1 briefly illustrate strategies that can be applied in fighting attacks and privacy issues in VANET. The functionality and purpose of VANET, however, are very effective if implemented successfully. Indeed, collisions in traffic can reduce, and the authorities can have a very easy time managing traffic. Also, as discussed earlier, response to emergencies on the roads can greatly improve. On the other hand. Shao et al. (2016) [16] explains that ways of administering security and privacy enhancement practices such as authentication are complex and therefore difficult to implement. It would require all vehicles to be registered [16]. Also, authentication requires personal identification details, which again is an issue especially in controlling them from being accessed by adversaries. But, with further research in the future, the solution to the discussed challenges and attacks can be reduced significantly. Also, VANET capabilities can be expanded as discussed in the “future work” section below. VII. FUTURE WORK Various companies have launched self-driving cars. VANETs can be integrated with the cars and help them in advancing their sensitivity capability of obstacles, infrastructure, and other vehicles in the traffic. With VANETs, driving experience for the self-drive vehicles can be improved where their reliability can greatly increase. Indeed, the challenge that was found in Uber’s self-driving trucks was the aspect of their low reliability, and significant improvement was recommended. 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