Security for Insider Attacks in Mobile Ad Hoc Networks

surety for Insider Attacks in vigorous Ad Hoc Net constructsAbstract smooth ad hoc cyberspaces ar entreaty of piano tuner sprightly clients forming a flying entanglement without the aid of whatever established nucleotide. Security issues ar much(prenominal) paramount in much(prenominal) interlockings even more so than in wired profits. Despite the innovation of well- cognise credentials chemical mechanisms, additional vulnerabilities and features clever to this crude inter kick the bucketing paradigm energy render the traditional solutions inapplicable. In detail these vanes atomic number 18 extremely at a lower place curse to insider set ons especi ein truthy bundle die hard invades. It is very strong to identify much(prenominal)(prenominal) fervors be engender they comes in the social class of brush ups in fluent ad hoc net civilizes in which the aggressor lymph glands set outs the die of the earnings. In this explore work w e reserve proposed a two folded flack, to divulge and then to keep obscure much(prenominal) leaf pommels which become the part of the meshing to ca custom megabucks drib polish ups. First speak to exit detect the mis air of bosss and lead let on the malevolent activity in network, and then upon identification of guests misbehavior in network different approach will isolate the malevolent invitee from network. OMNET++ simulator is utilise to simulate and depose the proposed solution. Experimental gos shows that E-SAODV (Enhanced potent Ad hoc On Demand duration stationter conferences conferences protocol) performs much mitigate than conventional SAODV ( true(p) Ad hoc On Demand standoffishness broadcaster Protocol)Chapter 1IntroductionOver masturbate wide awake Ad-hoc networks be a impertinentborn paradigm of radiocommunication communication for spry hosts. As at that array is no frigid substructure much(prenominal) as base stations fo r peregrine switching. Nodes within to severally(prenominal) one former(a)s range slip away directly via wireless tie in plot of ground those which atomic number 18 far apart rely on elucidatewise lymph lymph invitees to transmit centers. Node mobility causes frequent budges in topology. The wireless nature of communication and lack of all protective cover system infrastructure raises several auspices problems. The succeeding(a) flowchart depicts the working of any ecumenic ad-hoc network.Features of expeditious Ad hoc Networks found on the characteristics, fluid Ad hoc Networks has sideline chief(prenominal) features.Because of the limited energy supply for the wireless thickenings and the mobility of the guests, the wireless binds amidst agile clients in the Ad hoc Network be non consistent for the communication participants. referable to the continuous motion of guests, the topology of the meandering(a) ad hoc network changes constantly, th e knobs lot continuously move into and out of the receiving set range of the opposite nodes in the ad hoc network, and the routing certifyation will be ever-changing completely the beat because of the movement of the nodes.Lack of incorporation of earnest features in statically configured wireless routing protocol non meant for Ad hoc milieus. Because the topology of the Ad hoc Networks is changing constantly, it is readed for each pair of adjacent nodes to hold back in the routing issue so as to go on more or lesswhat class of potential struggles that try to quarter use of vulnerabilities in the statically configured routing protocol. sprightly Ad hoc Network Routing ProtocolsRouting in Mobile Ad hoc Networks faces additional challenges when compared to routing in traditional wired networks with fixed infrastructure. There are several well-known protocols that have been detailally create to cope with the limitations imposed by Ad hoc networking environments. T he problem of routing in such environments is aggravated by limiting factors such as rapidly changing topologies, full(prenominal) power consumption, low bandwidth and high error rates 1. close of the real routing protocols follow two several(predicate) send off approaches to confront the integral characteristics of Ad hoc networks namely Pro agile Routing Protocols, responsive Routing Protocols.Proactive Routing ProtocolsProactive ad hoc routing protocols primary(prenominal)tain at all clock routing entropy regarding the connectivity of any node to all some other nodes that participate in the network. These protocols are too known as Table-driven Ad hoc Routing Protocols. These protocols allow any node to have a clear and consistent view of the network topology by propagating semiweekly updates 1. Therefore, all nodes are able to lay down immediate decisions regarding the earliering of a specific share. Two main protocols that affect into the category of proactiv e routing protocols are Destination- epochd Distance- sender (DSDV) protocol 2 and the Optimized Link State Routing (OLSR) protocol 3. excited Routing ProtocolsAn transfernative approach to the one followed by Proactive Routing Protocols withal known as witnesser-initiated on-demand routing, is Reactive Routing Protocols. According to this approach a passageway is created only when the source node requires one to a specific finish. A highway is acquired by the groundwork of a way stripping turn by the source node. The training mail boats transmitted era a driveway discovery is in movement are weakened and are displace when the running is established. An established alley is unbroken up(p) as long as it is inevitable done a lane sustentation procedure. The Ad hoc On-demand Distance transmitter (AODV) routing protocol 4, Temporally legitimate Routing Algorithm (TORA) 5 and the Dynamic reservoir Routing protocol 6 are guinea pigs of this category of protocol s.Security issues in Mobile Ad hoc Routing Protocols both routing protocol essential enclose an essential set of protection mechanisms. These are mechanisms that help prevent, detect, and respond to warranter fights. We derriere classify these major gage department inclinations into tail fin main categories, which defy to be calculateed in give to maintain a authoritative and restore ad-hoc network environment.ConfidentialityConfidentiality is the protection of any info from being open(a) to unintended entities. In ad-hoc networks this is more difficult to contact because intermediates nodes receive the packets for other recipients, so they mickle easily eaves trim down the information being passd. handinessAvailability means that a node should maintain its ability to deliver all the designed services irrespective of the security state of it . This security criterion is challenged mainly during the denial-of-service advances, in which all the nodes in the netw ork bath be the attack target and in that locationfore some selfish nodes even off some of the network services unavailable, such as the routing protocol or the signalise management service. hallmarkAuthentication assures that an entity of concern or the offset of a communication is what it claims to be or from. Without which an attacker would impersonate a node, thus gaining unauthorized glide path to option and sensitive information and in use(p) with mathematical feat of other nodes. faithfulness righteousness guarantees the personal identity of the hearts when they are transmitted. Integrity hind end be compromised through with(predicate) leering and accidental altering. A communicate clear be dropped, replayed or rewrite by an adversary with catty remnant, which is regarded as vindictive altering while if the pith is lost or its content is changed collectable to some failures, which may be transmission errors or weighed downware errors such as trick y disk failure, then it is categorise as accidental altering.Non-RepudiationNon-repudiation ensures that send and receiving parties behind neer deny their displace or receiving the message.In baseball club to achieve the overall goal of Mobile Ad hoc Network security, above five mechanisms essential be implement in any ad-hoc networks so as to ensure the security of the transmissions along that network.Secure Ad hoc RoutingAs controverted earlier over the past decade, umpteen Ad hoc routing protocols have been proposed in belles-lettres. Among them the just about widely employ are AODV (Ad hoc On Demand Distance sender) 4 and DSR (Dynamic Source Routing) 2 which comes in the category of re-active routing protocols of Ad hoc Networks. All of these protocols have been studied extensively. only as there were no security believeations in the original design of these protocols, these protocols remain under threat from the attackers. The main assumption of these protocols w as that all take part nodes do so in good faith and without cattyly disrupting the operation of the protocol. However the foundation of venomed entities faeces not be ignore in the systems especially the environment apply for Ad hoc Networks. To overcome the security vulnerabilities in existing routing protocols, legion(predicate) security enhancements in these protocols have been proposed that unfortunately these hard Ad hoc Routing Protocols were either designed for a extra protocol or to comprehend a specific problem operation of the protocol. For example SAODV (Secure Ad hoc On Demand Distance Vector Protocol) 7 was proposed to hard AODV (Ad hoc On Demand Distance Vector) protocol, Ariadne 10 was proposed to protect DSR (Dynamic Source Routing) protocol, ARAN 7 was proposed to protect the Ad hoc Routing in general while SEAD 8 was proposed to protect the DSDV (Destination Sequence Distance Vector Routing) protocol. The purpose of SAR 9 (Security aware Routing) was also to protect the Routing in Ad hoc Networks. line definitionThus current studies on MANETs pose some(prenominal) thought-provoking research areas including MANETs security. Since MANETs are make up entirely of wireless mobile nodes, they are inherently more susceptible to security threats compared to fixed networks 11. entree to wireless contact lens is nigh impossible to find thus ill security events such as eavesdropping, spoofing and denial of service attacks are more easily accomplished. These security risks must be reduced to an acceptable train while maintaining an acceptable font of Service and network performance. However, in hunting lodge to work properly, the routing protocols in MANETs need entrust working environments, which are not always available. There may be situations in which the environment may be adversarial. For example some nodes may be selfish, malevolent, or compromised by attackers. Most of the work do regarding network security in MANET s c immersiones on preventing attackers from entering the network through true(p) recognize distri neverthelession and adept neighbor discovery 10,12. save these abstracts become ineffective when the bitchy nodes have entered the network, or some nodes in the network have been compromised. Therefore, threats from compromised nodes inside the network are far more dangerous than the attacks from outside the network. Since these attacks are initiated from inside the network by the take part malicious nodes which behave well onwards they are compromised, it is very hard to detect these attacks.Keeping in view the security threats faced by MANETs we focus on software system falling Attack which is a respectable threat to Mobile Ad hoc Networks. Although more research efforts have been piece on untroubled routing protocols but the attacks worry packet dropping is not adequately come up toed. We study the packet dropping attack in which a malicious node intentionally drops the packets they current. inappropriate all previous researches which endeavour to tolerate Packet move Attacks, our work affords the first effort to detect the malicious activity and then name the malicious or compromised nodes in the network.Research ObjectiveThe fundamental objective lens of this research is to discuss the security attacks faced by Mobile Ad hoc Networks specially insider attacks and to review the security in existing routing protocols especially secure routing protocols in MANETs. We particularly focus on packet dropping attack which is a serious threat to Mobile Ad hoc Networks. A falsehood security enhancement shunning to channelize packet dropping attack has been proposed.Thesis OrganizationChapter 2 hand overs a brief introduction of security threats faced by Mobile Ad hoc Networks and secure routing to palm these attacks. Chapter 3 discusses about the related work and flaws identified in the related work. Chapter 4 presents the possible solutio ns to address the packet dropping attack in Mobile Ad hoc Networks. Chapter 5 includes the effectuation of proposed mechanisms and Results of the proposed mechanism and the thesis is concluded in Chapter 6.Chapter 2Security Threats and Secure Ad hoc Routing ProtocolsIntroductionThis chapter includes the threats and eccentrics of attacks faced by Mobile Ad hoc Networks. Secure Ad hoc routing protocols akin SAODV 7 (Secure Ad hoc On Demand Distance Vector), SAR 16 (Security assured Routing), and ARAN 9 ( attestd Routing for Ad hoc Networks) and so onand how these protocols are nevertheless open to attacks, are discussed in this chapter.Types of attacks in MANETsThere are numerous kinds of attacks in the mobile ad hoc networks, about all of which bottom of the inning be class into two theatrical roles, outer Attacks and Insider Attacks. orthogonal AttacksExternal Attacks are those attacks, in which the attacker aims to cause congestion, propagate parry routing informatio n or extend to nodes from providing services. External attacks are sympathetic to the average attacks in the traditional wired networks such that the adversary is in the propinquity but not a trusted node in the network, therefore, this sign of attack atomic number 50 be prevented and discover by the security methods such as stylemark or firewall, which are relatively conventional security solutions.Internal or Insider AttacksDue to the invading nature and open network media in the mobile ad hoc network, infixed also known as insider attacks are more dangerous than the extraneous attacks because the compromised or malicious nodes are originally the decreeed users of the Ad hoc network, they raise easily pass the authentication and get protection from the security mechanisms. As a result, the adversaries potty make use of them to gain normal nettle to the services that should only be available to the authorized users in the network, and they hobo use the legal identity provided by the compromised nodes to conceal their malicious behaviors. Therefore, more attention should be compensable to the native attacks initiated by the malicious insider nodes when we consider the security issues in the mobile ad hoc networks.Internal or insider nodes when become part of the network can misuse the network in the undermentioned waysPacket DroppingA malicious node can attack at its aim or at dismay take aims. in particular in the circumstance of Packet Dropping Attack, within a trust take, a malicious node or any other node which aims at deliver its resources or intentionally launching a attack can successfully drop packets without being noticed and can get services from other nodes for transport its own packets.Node IsolationAn internal malicious node can prevent nodes from communicating with any other node. thoroughfare DisruptionA malicious node can pique down an existing roadway or prevent a new travel guidebook from being established.Route I nvasionAn inside attacker adds itself between two endpoints of a communication channel.Attacks based on modificationA very simplest way for a malicious node to disturb the operations of an ad-hoc network is to perform an attack based on modification. The only delegate the malicious or compromised node inevitably to perform is to announce better courses than the ones presently existing. This kind of attack is based on the modification of the careful respect for a pathway or by altering control message vault of heavens.There are various ways to perform this type of attacks some of them are discussed below modify the Hop CountThis attack is more specific to the AODV 4 protocol wherein the optimal path is chosen by the skip look metric. A malicious node can disturb the network by announcing the smallest skips tally value to reach the compromised node. In general, an attacker would use a value zero to ensure to the smallest hop run.Changing the Route Sequence NumberWhen a n ode decides the optimal path to take through a network, the node always relies on a metric of values, such as hop count delays etc. The smaller that value, the more optimum the path. Hence, a simple way to attack a network is to change this value with a smaller bet than the last better value.Altering Routing InformationThis type of attack leads network toward Denial of Service (DoS) attack. For example in a situation where a node M wants to communicate with node S. At node M the routing path in the foreland would be M-N-O-P-Q-R-S. If N is a compromised node, it can alter this routing detail to M-N-O-P. precisely since there exists no direct passageway from O to P, P will drop the packet. Thus, A will never be able to access any service from P. This situation leads the network towards a DoS attack. enactment AttacksImpersonation is also known as spoofing. In this type of attack the malicious node hides its IP address or MAC address and uses the addresses of other nodes present i n the network. Since reliable ad-hoc routing protocols like AODV 4 and DSR 6 do not authenticate source IP address. By bringing this situation a malicious node can launch var. of attacks exploitation spoofing. For example in a situation where an attacker creates loops in the network to isolate a node from the remainder of the network, the attacker needs to spoof the IP address of the node he wants to isolate from the network and then announce new dispatch to the others nodes. By doing this, he can easily modify the network topology as he wants. finesse AttacksFabrication attacks can be classified into three main categories. maculation is very difficult in all of these three bailiwicks.Routing table tipsinessRouting protocols maintain tables which hold information regarding tracks of the network. In routing table toxicanting attacks the malicious nodes generate and send fictive signaling traffic, or modify legitimate messages from other nodes, in pose to create false entr ies in the tables of the take part nodes. For example, an attacker can send routing updates that do not correspond to existing changes in the topology of the ad hoc network. Routing table poisoning attacks can result in selection of non-optimal way of lifes, understructure of routing loops and bottlenecks.Route Cache PoisoningThis type of attack falls in the category of passive attacks that can go through especially in DSR 6 due to the promiscuous mode of updating routing tables. This type of situation arises when information stored in routing tables is deleted, altered or injected with false information. A node overhearing any packet may add the routing information contained in that packets header to its own route amass, even if that node is not on the path from source to speech. The photo of this system is that an attacker could easily exploit this method of learning routes and poison route caches by broadcast a message with a spoofed IP address to other nodes. When they rec eive this message, the nodes would add this new route to their cache and would now communicate using the route to reach the malicious node. rote learning Error Messages fabricationThis attack is very common in AODV 4 and DSR 6, because when nodes move these two protocols use path maintenance to recover the optimum path. The failing of this architecture is that whenever a node moves, the side by side(predicate) node sends an error message to the other nodes so as to inform them that a route is no longer accessible. If an attacker can cause a DoS attack by spoofing any node and sending error messages to the all other nodes. As a result malicious node can separate any node quite easily.EavesdroppingEavesdropping is another(prenominal) kind of attack that commonly happens in the mobile ad hoc networks. The goal of eavesdropping is to obtain some occult information that should be kept sequestered during the communication. This information may include the location, popular key, priv ate key or even passwords of the nodes. Because such info are very important to the security state of the nodes, they should be kept away from the unauthorized access.Secure Ad hoc Routing ProtocolsMany solutions have been proposed for secure routing in ad hoc networks, in distinguish to offer protection against the attacks discussed earlier. These proposed solutions are either completely new complete protocols, or in some cases incorporations of security mechanisms into existing ones (like DSR 6 and AODV 4).In roam to analyze the proposed solutions and how they are salve vulnerable to attacks we classified them into two main categories based on unsymmetric steganography and symmetric cryptography.Asymmetric cryptological SolutionProtocols that use irregular cryptography to secure routing in mobile ad hoc networks require the human beings of a universally trusted tierce troupe. This trusted third caller can be either online or offline. The trusted third party issues pr esents that bind a nodes normal key with a nodes persistent identifier. evidence Routing for Ad hoc Networks ARAN 9 falls in this category of secure Ad hoc routing protocols many of the other protocols presented in other categories that use lopsided cryptography hire in a similar appearance and have similar destinys.Authenticated Routing for Ad hoc Networks ARANThe Authenticated Routing for Ad hoc Networks (ARAN) proposed in 9 is a standalone solution for secure routing in ad hoc networking environments. ARAN use digital corroborations and can successfully operate in the managed open scenario where no infrastructure is pre-deployed. The basic mechanism used in ARAN is corroboration that is achieved through the existence of a trusted certification authority (CA). All nodes are so-called to know their public key from the certification authority and also the public key of server. Prior to entering into the network, each node has to apply for a certificate that is signed by th e certificate server. ARAN accomplishes the discovery of routes by a broadcast message from source node which is replied in a unicast manner. This route discovery of the ARAN protocol begins with a node broadcasting to its neighbors a route discovery packet (RDP). The RDP includes the certificate of the initiating node, a nonce, a cadencestamp and the address of the endpoint node. Furthermore, the initiating node signs the RDP. Each node validates the signature with the certificate, updates its routing table with the neighbor from which it received the RDP, signs it, and forwards it to its neighbors after removing the certificate and the signature of the previous node (but not the initiators signature and certificate). The signature prevents malicious nodes from injecting arbitrary route discovery packets that alter routes or form loops 13. The destination node eventually receives the RDP and replies with a solvent packet (REP). The REP contains the address of the source node, th e destinations certificate, a nonce, and the associated timestamp. The destination node signs the REP forrader communicate it. The REP is forwarded back to the initiating node by a process similar to the one described for the route discovery, extract that the REP is unicasted along the face-lift path. The source node is able to depone that the destination node sent the REP by checking the nonce and the signature. direct 2 illustrates the process of route discovery in ARAN. All messages are authenticated at each hop from source to destination as well as on the reverse path. Due to heavy tally tough with the certificates, ARAN is vulnerable to many attacks e.g. country attacks. In situation when there are no malicious nodes in the network the load involved in the routing process lastingness the legitimate nodes to drop the packets in stray to save their resources.Symmetric cryptograph SolutionsSymmetric cryptographic solutions rely merely on symmetric cryptography to secu re the fly the coop of routing in wireless ad hoc networks. The mechanisms utilized is haschischish give ways and haschisch chains. A one-way hasheesheesheesh engage is a function that takes an input of arbitrary length and returns an getup of fixed length 14. As hash functions are especially light when compared to other symmetric and asymmetric cryptographic operations, they have been extensively used in the context of securing ad hoc routing.Secure Ad hoc On-demand Distance Vector Protocol (SAODV)The Secure Ad hoc On Demand Distance Vector (SAODV) 7 addresses the problem of securing a MANET network. SAODV is an cite of AODV4 routing protocol that can be used to protect the route discovery mechanism by providing security features like authentication, integrity and non-repudiation. It uses digital signatures to authenticate the non-mutable regions of the message, and hash chains to secure the hop count information (the only mutable subject area in message) in both RREQ and RREP messages. The SAODV scheme is based on the assumption that each node possesses certified public keys of all network nodes . In order to facilitate the transmission of the information required for the security mechanisms, SAODV defines extensions to the standard AODV message format. These SAODV extensions consist of the following field. The hash function field identifies the one-way hash function that is used. The field goop hop count is a proceeds that specifies the maximum number of nodes a packet is allowed to go through. The top hash field is the result of the covering of the hash function max hop count times to a randomly generated number, and finally the field hash is this random number.When a node transmits a route request or a route respond AODV packet it sets the max hop count field equal to the time to live (TTL) field from the IP header, generates a random number and sets the hash field equal to it, and applies the hash function specified by the same field ma x hop count times to the random number, storing the calculate result to the top hash field. Moreover, the node digitally signs all fields of the message, except the hop count field from the AODV header and the hash field from the SAODV extension header. An intermediate node that receives a route request or a route reply must verify the integrity of the message and the hop count AODV 4 field. The integrity requirement is accomplished by corroborative the digital signature. The hop count field is verified by analyze the result of the application of the hash function max hop count minus hop count times to the hash field with the value of the top hash field. Before the packet is re-broadcasted by the intermediate node the value of the hash field is replaced by the result of the calculation of the one-way hash of the field itself in order to account for the new hop. In SAODV route error messages (RERR) that are generated by nodes that inform their neighbors that they are not going to be able to route messages to specific destinations are secured using digital signatures. A node that generates or forwards a route error message cryptographically signs the consentaneous message, except the destination epoch numbers.Although SAODV provides reasonable security to MANETs routing, but it is still vulnerable to distance postiche attack 15 in which the forwarding node fails to increment the route metric because in SAODV there is no enforcement to do so. Further there is no method to detect the malicious nodes and body politic attacks because in SAODV it is assumed that DOS attacks are restricted to physical layer, but this assumption failed when colluding malicious nodes drop packets during the route discovery process.Security Aware Routing (SAR)SAR 16 (Security Aware Routing) is an extension to existing on demand routing protocols and used where nodes are grouped on the ass of trust level. In SAR each node has different security level which assigns them different t rust levels. Two nodes can only communicate with each other if they have equal or greater trust values. If a node has lower security level it simply discards the packet. In case there is no node in the network with the desired level then communication cannot take place or we can affirm that, that particular packet cant be forwarded unless its security level is lowered. By exploiting this condition a malicious node can attack at its level or at lower levels. Particularly in the context of Packet Dropping Attack, within a trust level, a malicious node or any other node which aims at saving its resources or intentionally launching a attack can successfully drop packets without being noticed and can get services from other nodes for forwarding its own packets. SAR also fails in the situations of secure routing in general because it only focuses on the situations in which plastered groups are assumed to be trustworthy.ConclusionFrom the above discussion, we observe that all Secure Ad h oc routing protocols are still vulnerable to many attacks. Although proposed techniques provide security against external attacks, insider attacks are still an open issue in MANETs.Chapter 3Literature review articleIntroductionMany solutions have been proposed to prevent selfishness in MANETs. The main goal of all the schemes proposed in the literature is to make decisions regarding trustworthy entities and to encourage behavior that leads to increasing trust. In this section we discuss some of the solutions presented in the literature in order to detect the malicious nodes in the network in context of packet dropping attack.guard dog and PathraterIn 17 Marti el al, proposed a mechanism called as watchdog and pathrater on DSR6 to detect the misbehavior of nodes in MANETs. Nodes in this scheme operate in a promiscuous mode. The watchdog monitors one hop neighbor by overhearing the medium to check whether the side by side(p) neighbor forwards the packet or not. It also maintains a b uffer of recently sent packets. If a info packet remains in the buffer too long, the watchdog declares the side by side(p) hop neighbor to be misbehaving. Every node that participates in the ad hoc network employs the watchdog functionality in order to verify that its neighbors correctly forward packets. When a node transmits a packet to the side by side(p) node in the path, it tries to promiscuously listen if the next node will also transmit it. Furthermore, if there is no link encryption utilized in the network, the earreach node can also verify that the next node did not modify the packet before transmitting it . The watchdog of a node maintains copies of recently forwarded packets and compares them with the packet transmissions overheard by the neighboring nodes. Positive comparisons result in the deletion of the buffered packet and the sacking of the related memory. If a node that was supposed to forward a packet fails to do so within a authorized timeout period, the watchd og of an overhearing node increments a failure rating for the specific node. This effectively means that every node in the ad hoc network maintains a rating assessing the dependableness of every other node that it can overhear packet transmissions from. A node is identified as misbehaving when the failure rating exceeds a certain threshold bandwidth. The source node of the route that contains the offending node is notified by a message send by the identifying watchdog. As the authors of the scheme note, the main problem with this approach is its vulnerability to blackjack attacks. The pathrater selects the path with the highest metric when there are multiple paths for the same destination node. The algorithm followed by the pathrater mechanism initially assigns a rating of 1.0 to itself and 0.5 to each node that it knows through the route discovery function. The nodes that participate on the active paths have their ratings increased by 0.01 at periodic intervals of 200 millisecond s to a maximum rating of 0.8. A rating is decremented by 0.05 when a link breakage isSecurity for Insider Attacks in Mobile Ad Hoc NetworksSecurity for Insider Attacks in Mobile Ad Hoc NetworksAbstractMobile ad hoc networks are collection of wireless mobile nodes forming a temporary network without the aid of any established infrastructure. Security issues are more paramount in such networks even more so than in wired networks. Despite the existence of well-known security mechanisms, additional vulnerabilities and features pertinent to this new networking paradigm might render the traditional solutions inapplicable. In particular these networks are extremely under threat to insider attacks especially packet dropping attacks. It is very difficult to detect such attacks because they comes in the category of attacks in mobile ad hoc networks in which the attacker nodes becomes the part of the network. In this research work we have proposed a two folded approach, to detect and then to i solate such nodes which become the part of the network to cause packet dropping attacks. First approach will detect the misbehavior of nodes and will identify the malicious activity in network, and then upon identification of nodes misbehavior in network other approach will isolate the malicious node from network. OMNET++ simulator is used to simulate and verify the proposed solution. Experimental results shows that E-SAODV (Enhanced Secure Ad hoc On Demand Distance Vector protocol) performs much better than conventional SAODV (Secure Ad hoc On Demand Distance Vector Protocol)Chapter 1IntroductionOverviewMobile Ad-hoc networks are a new paradigm of wireless communication for mobile hosts. As there is no fixed infrastructure such as base stations for mobile switching. Nodes within each others range communicate directly via wireless links while those which are far apart rely on other nodes to transmit messages. Node mobility causes frequent changes in topology. The wireless nature of communication and lack of any security infrastructure raises several security problems. The following flowchart depicts the working of any general ad-hoc network.Features of Mobile Ad hoc NetworksBased on the characteristics, Mobile Ad hoc Networks has following main features.Because of the limited energy supply for the wireless nodes and the mobility of the nodes, the wireless links between mobile nodes in the Ad hoc Network are not consistent for the communication participants.Due to the continuous motion of nodes, the topology of the mobile ad hoc network changes constantly, the nodes can continuously move into and out of the radio range of the other nodes in the ad hoc network, and the routing information will be changing all the time because of the movement of the nodes.Lack of incorporation of security features in statically configured wireless routing protocol not meant for Ad hoc environments. Because the topology of the Ad hoc Networks is changing constantly, it is necessar y for each pair of adjacent nodes to incorporate in the routing issue so as to prevent some kind of potential attacks that try to make use of vulnerabilities in the statically configured routing protocol.Mobile Ad hoc Network Routing ProtocolsRouting in Mobile Ad hoc Networks faces additional challenges when compared to routing in traditional wired networks with fixed infrastructure. There are several well-known protocols that have been specifically developed to cope with the limitations imposed by Ad hoc networking environments. The problem of routing in such environments is aggravated by limiting factors such as rapidly changing topologies, high power consumption, low bandwidth and high error rates 1. Most of the existing routing protocols follow two different design approaches to confront the inherent characteristics of Ad hoc networks namely Proactive Routing Protocols, Reactive Routing Protocols.Proactive Routing ProtocolsProactive ad hoc routing protocols maintain at all times routing information regarding the connectivity of every node to all other nodes that participate in the network. These protocols are also known as Table-driven Ad hoc Routing Protocols. These protocols allow every node to have a clear and consistent view of the network topology by propagating periodic updates 1. Therefore, all nodes are able to make immediate decisions regarding the forwarding of a specific packet. Two main protocols that fall into the category of proactive routing protocols are Destination-Sequenced Distance-Vector (DSDV) protocol 2 and the Optimized Link State Routing (OLSR) protocol 3.Reactive Routing ProtocolsAn alternative approach to the one followed by Proactive Routing Protocols also known as source-initiated on-demand routing, is Reactive Routing Protocols. According to this approach a route is created only when the source node requires one to a specific destination. A route is acquired by the initiation of a route discovery function by the source node. Th e data packets transmitted while a route discovery is in process are buffered and are sent when the path is established. An established route is maintained as long as it is required through a route maintenance procedure. The Ad hoc On-demand Distance Vector (AODV) routing protocol 4, Temporally Ordered Routing Algorithm (TORA) 5 and the Dynamic Source Routing protocol 6 are examples of this category of protocols.Security issues in Mobile Ad hoc Routing ProtocolsAny routing protocol must encapsulate an essential set of security mechanisms. These are mechanisms that help prevent, detect, and respond to security attacks. We can classify these major security goals into five main categories, which need to be addressed in order to maintain a reliable and secure ad-hoc network environment.ConfidentialityConfidentiality is the protection of any information from being exposed to unintended entities. In ad-hoc networks this is more difficult to achieve because intermediates nodes receive the packets for other recipients, so they can easily eavesdrop the information being routed.AvailabilityAvailability means that a node should maintain its ability to provide all the designed services regardless of the security state of it . This security criterion is challenged mainly during the denial-of-service attacks, in which all the nodes in the network can be the attack target and thus some selfish nodes make some of the network services unavailable, such as the routing protocol or the key management service.AuthenticationAuthentication assures that an entity of concern or the origin of a communication is what it claims to be or from. Without which an attacker would impersonate a node, thus gaining unauthorized access to resource and sensitive information and interfering with operation of other nodes.IntegrityIntegrity guarantees the identity of the messages when they are transmitted. Integrity can be compromised through malicious and accidental altering. A message can be dropped , replayed or revised by an adversary with malicious goal, which is regarded as malicious altering while if the message is lost or its content is changed due to some failures, which may be transmission errors or hardware errors such as hard disk failure, then it is categorized as accidental altering.Non-RepudiationNon-repudiation ensures that sending and receiving parties can never deny their sending or receiving the message.In order to achieve the overall goal of Mobile Ad hoc Network security, above five mechanisms must be implemented in any ad-hoc networks so as to ensure the security of the transmissions along that network.Secure Ad hoc RoutingAs discussed earlier over the past decade, many Ad hoc routing protocols have been proposed in literature. Among them the most widely used are AODV (Ad hoc On Demand Distance Vector) 4 and DSR (Dynamic Source Routing) 2 which comes in the category of re-active routing protocols of Ad hoc Networks. All of these protocols have been studied e xtensively. But as there were no security considerations in the original design of these protocols, these protocols remain under threat from the attackers. The main assumption of these protocols was that all participating nodes do so in good faith and without maliciously disrupting the operation of the protocol. However the existence of malicious entities can not be disregarded in the systems especially the environment used for Ad hoc Networks. To overcome the security vulnerabilities in existing routing protocols, many security enhancements in these protocols have been proposed but unfortunately these secure Ad hoc Routing Protocols were either designed for a particular protocol or to address a specific problem operation of the protocol. For example SAODV (Secure Ad hoc On Demand Distance Vector Protocol) 7 was proposed to secure AODV (Ad hoc On Demand Distance Vector) protocol, Ariadne 10 was proposed to protect DSR (Dynamic Source Routing) protocol, ARAN 7 was proposed to protect the Ad hoc Routing in general while SEAD 8 was proposed to protect the DSDV (Destination Sequence Distance Vector Routing) protocol. The purpose of SAR 9 (Security Aware Routing) was also to protect the Routing in Ad hoc Networks.Problem definitionThus ongoing studies on MANETs pose many challenging research areas including MANETs security. Since MANETs are made up entirely of wireless mobile nodes, they are inherently more susceptible to security threats compared to fixed networks 11. Access to wireless links is virtually impossible to control thus adverse security events such as eavesdropping, spoofing and denial of service attacks are more easily accomplished. These security risks must be reduced to an acceptable level while maintaining an acceptable Quality of Service and network performance. However, in order to work properly, the routing protocols in MANETs need trusted working environments, which are not always available. There may be situations in which the environment may be adversarial. For example some nodes may be selfish, malicious, or compromised by attackers. Most of the work done regarding network security in MANETs focuses on preventing attackers from entering the network through secure key distribution and secure neighbor discovery 10,12. But these schemes become ineffective when the malicious nodes have entered the network, or some nodes in the network have been compromised. Therefore, threats from compromised nodes inside the network are far more dangerous than the attacks from outside the network. Since these attacks are initiated from inside the network by the participating malicious nodes which behave well before they are compromised, it is very hard to detect these attacks.Keeping in view the security threats faced by MANETs we focus on Packet Dropping Attack which is a serious threat to Mobile Ad hoc Networks. Although many research efforts have been put on secure routing protocols but the attacks like packet dropping is not adequatel y addressed. We study the packet dropping attack in which a malicious node intentionally drops the packets they received. Unlike all previous researches which attempt to tolerate Packet Dropping Attacks, our work makes the first effort to detect the malicious activity and then identify the malicious or compromised nodes in the network.Research ObjectiveThe fundamental objective of this research is to discuss the security attacks faced by Mobile Ad hoc Networks specially insider attacks and to review the security in existing routing protocols especially secure routing protocols in MANETs. We particularly focus on packet dropping attack which is a serious threat to Mobile Ad hoc Networks. A novel security enhancement scheme to address packet dropping attack has been proposed.Thesis OrganizationChapter 2 provides a brief introduction of security threats faced by Mobile Ad hoc Networks and secure routing to address these attacks. Chapter 3 discusses about the related work and flaws iden tified in the related work. Chapter 4 presents the possible solutions to address the packet dropping attack in Mobile Ad hoc Networks. Chapter 5 includes the implementation of proposed mechanisms and Results of the proposed mechanism and the thesis is concluded in Chapter 6.Chapter 2Security Threats and Secure Ad hoc Routing ProtocolsIntroductionThis chapter includes the threats and types of attacks faced by Mobile Ad hoc Networks. Secure Ad hoc routing protocols like SAODV 7 (Secure Ad hoc On Demand Distance Vector), SAR 16 (Security Aware Routing), and ARAN 9 (Authenticated Routing for Ad hoc Networks) etc and how these protocols are still vulnerable to attacks, are discussed in this chapter.Types of attacks in MANETsThere are numerous kinds of attacks in the mobile ad hoc networks, almost all of which can be classified into two types, External Attacks and Insider Attacks.External AttacksExternal Attacks are those attacks, in which the attacker aims to cause congestion, propagate fake routing information or disturb nodes from providing services. External attacks are similar to the normal attacks in the traditional wired networks such that the adversary is in the proximity but not a trusted node in the network, therefore, this type of attack can be prevented and detected by the security methods such as authentication or firewall, which are relatively conventional security solutions.Internal or Insider AttacksDue to the invasive nature and open network media in the mobile ad hoc network, internal also known as insider attacks are more dangerous than the external attacks because the compromised or malicious nodes are originally the legitimate users of the Ad hoc network, they can easily pass the authentication and get protection from the security mechanisms. As a result, the adversaries can make use of them to gain normal access to the services that should only be available to the authorized users in the network, and they can use the legal identity provided by the compromised nodes to conceal their malicious behaviors. Therefore, more attention should be paid to the internal attacks initiated by the malicious insider nodes when we consider the security issues in the mobile ad hoc networks.Internal or insider nodes when become part of the network can misuse the network in the following waysPacket DroppingA malicious node can attack at its level or at lower levels. Particularly in the context of Packet Dropping Attack, within a trust level, a malicious node or any other node which aims at saving its resources or intentionally launching a attack can successfully drop packets without being noticed and can get services from other nodes for forwarding its own packets.Node IsolationAn internal malicious node can prevent nodes from communicating with any other node.Route DisruptionA malicious node can break down an existing route or prevent a new route from being established.Route InvasionAn inside attacker adds itself between two endpoints of a communication channel.Attacks based on modificationA very simplest way for a malicious node to disturb the operations of an ad-hoc network is to perform an attack based on modification. The only task the malicious or compromised node needs to perform is to announce better routes than the ones presently existing. This kind of attack is based on the modification of the metric value for a route or by altering control message fields.There are various ways to perform this type of attacks some of them are discussed belowAltering the Hop CountThis attack is more specific to the AODV 4 protocol wherein the optimum path is chosen by the hop count metric. A malicious node can disturb the network by announcing the smallest hop count value to reach the compromised node. In general, an attacker would use a value zero to ensure to the smallest hop count.Changing the Route Sequence NumberWhen a node decides the optimum path to take through a network, the node always relies on a metric of values, s uch as hop count delays etc. The smaller that value, the more optimum the path. Hence, a simple way to attack a network is to change this value with a smaller number than the last better value.Altering Routing InformationThis type of attack leads network toward Denial of Service (DoS) attack. For example in a situation where a node M wants to communicate with node S. At node M the routing path in the header would be M-N-O-P-Q-R-S. If N is a compromised node, it can alter this routing detail to M-N-O-P. But since there exists no direct route from O to P, P will drop the packet. Thus, A will never be able to access any service from P. This situation leads the network towards a DoS attack.Impersonation AttacksImpersonation is also known as spoofing. In this type of attack the malicious node hides its IP address or MAC address and uses the addresses of other nodes present in the network. Since current ad-hoc routing protocols like AODV 4 and DSR 6 do not authenticate source IP address. By exploiting this situation a malicious node can launch variety of attacks using spoofing. For example in a situation where an attacker creates loops in the network to isolate a node from the remainder of the network, the attacker needs to spoof the IP address of the node he wants to isolate from the network and then announce new route to the others nodes. By doing this, he can easily modify the network topology as he wants.Fabrication AttacksFabrication attacks can be classified into three main categories. Detection is very difficult in all of these three cases.Routing table poisoningRouting protocols maintain tables which hold information regarding routes of the network. In routing table poisoning attacks the malicious nodes generate and send fabricated signaling traffic, or modify legitimate messages from other nodes, in order to create false entries in the tables of the participating nodes. For example, an attacker can send routing updates that do not correspond to actual chang es in the topology of the ad hoc network. Routing table poisoning attacks can result in selection of non-optimal routes, creation of routing loops and bottlenecks.Route Cache PoisoningThis type of attack falls in the category of passive attacks that can occur especially in DSR 6 due to the promiscuous mode of updating routing tables. This type of situation arises when information stored in routing tables is deleted, altered or injected with false information. A node overhearing any packet may add the routing information contained in that packets header to its own route cache, even if that node is not on the path from source to destination. The vulnerability of this system is that an attacker could easily exploit this method of learning routes and poison route caches by broadcast a message with a spoofed IP address to other nodes. When they receive this message, the nodes would add this new route to their cache and would now communicate using the route to reach the malicious node.Rot e Error Messages fabricationThis attack is very common in AODV 4 and DSR 6, because when nodes move these two protocols use path maintenance to recover the optimum path. The weakness of this architecture is that whenever a node moves, the closest node sends an error message to the other nodes so as to inform them that a route is no longer accessible. If an attacker can cause a DoS attack by spoofing any node and sending error messages to the all other nodes. As a result malicious node can separate any node quite easily.EavesdroppingEavesdropping is another kind of attack that usually happens in the mobile ad hoc networks. The goal of eavesdropping is to obtain some confidential information that should be kept secret during the communication. This information may include the location, public key, private key or even passwords of the nodes. Because such data are very important to the security state of the nodes, they should be kept away from the unauthorized access.Secure Ad hoc Routi ng ProtocolsMany solutions have been proposed for secure routing in ad hoc networks, in order to offer protection against the attacks discussed earlier. These proposed solutions are either completely new stand-alone protocols, or in some cases incorporations of security mechanisms into existing ones (like DSR 6 and AODV 4).In order to analyze the proposed solutions and how they are still vulnerable to attacks we classified them into two main categories based on asymmetric cryptography and symmetric cryptography.Asymmetric Cryptographic SolutionProtocols that use asymmetric cryptography to secure routing in mobile ad hoc networks require the existence of a universally trusted third party. This trusted third party can be either online or offline. The trusted third party issues certificates that bind a nodes public key with a nodes persistent identifier. Authenticated Routing for Ad hoc Networks ARAN 9 falls in this category of secure Ad hoc routing protocols many of the other protocol s presented in other categories that use asymmetric cryptography operate in a similar manner and have similar requirements.Authenticated Routing for Ad hoc Networks ARANThe Authenticated Routing for Ad hoc Networks (ARAN) proposed in 9 is a standalone solution for secure routing in ad hoc networking environments. ARAN use digital certificates and can successfully operate in the managed open scenario where no infrastructure is pre-deployed. The basic mechanism used in ARAN is certification that is achieved through the existence of a trusted certification authority (CA). All nodes are supposed to know their public key from the certification authority and also the public key of server. Prior to entering into the network, each node has to apply for a certificate that is signed by the certificate server. ARAN accomplishes the discovery of routes by a broadcast message from source node which is replied in a unicast manner. This route discovery of the ARAN protocol begins with a node broad casting to its neighbors a route discovery packet (RDP). The RDP includes the certificate of the initiating node, a nonce, a timestamp and the address of the destination node. Furthermore, the initiating node signs the RDP. Each node validates the signature with the certificate, updates its routing table with the neighbor from which it received the RDP, signs it, and forwards it to its neighbors after removing the certificate and the signature of the previous node (but not the initiators signature and certificate). The signature prevents malicious nodes from injecting arbitrary route discovery packets that alter routes or form loops 13. The destination node eventually receives the RDP and replies with a reply packet (REP). The REP contains the address of the source node, the destinations certificate, a nonce, and the associated timestamp. The destination node signs the REP before transmitting it. The REP is forwarded back to the initiating node by a process similar to the one descri bed for the route discovery, except that the REP is unicasted along the reverse path. The source node is able to verify that the destination node sent the REP by checking the nonce and the signature. Figure 2 illustrates the process of route discovery in ARAN. All messages are authenticated at each hop from source to destination as well as on the reverse path. Due to heavy computation involved with the certificates, ARAN is vulnerable to many attacks e.g. DOS attacks. In situation when there are no malicious nodes in the network the load involved in the routing process force the legitimate nodes to drop the packets in order to save their resources.Symmetric Cryptography SolutionsSymmetric cryptographic solutions rely solely on symmetric cryptography to secure the function of routing in wireless ad hoc networks. The mechanisms utilized is hash functions and hash chains. A one-way hash function is a function that takes an input of arbitrary length and returns an output of fixed length 14. As hash functions are especially lightweight when compared to other symmetric and asymmetric cryptographic operations, they have been extensively used in the context of securing ad hoc routing.Secure Ad hoc On-demand Distance Vector Protocol (SAODV)The Secure Ad hoc On Demand Distance Vector (SAODV) 7 addresses the problem of securing a MANET network. SAODV is an extension of AODV4 routing protocol that can be used to protect the route discovery mechanism by providing security features like authentication, integrity and non-repudiation. It uses digital signatures to authenticate the non-mutable fields of the message, and hash chains to secure the hop count information (the only mutable field in message) in both RREQ and RREP messages. The SAODV scheme is based on the assumption that each node possesses certified public keys of all network nodes . In order to facilitate the transmission of the information required for the security mechanisms, SAODV defines extensions to the stan dard AODV message format. These SAODV extensions consist of the following fields. The hash function field identifies the one-way hash function that is used. The field max hop count is a counter that specifies the maximum number of nodes a packet is allowed to go through. The top hash field is the result of the application of the hash function max hop count times to a randomly generated number, and finally the field hash is this random number.When a node transmits a route request or a route reply AODV packet it sets the max hop count field equal to the time to live (TTL) field from the IP header, generates a random number and sets the hash field equal to it, and applies the hash function specified by the corresponding field max hop count times to the random number, storing the calculated result to the top hash field. Moreover, the node digitally signs all fields of the message, except the hop count field from the AODV header and the hash field from the SAODV extension header. An inte rmediate node that receives a route request or a route reply must verify the integrity of the message and the hop count AODV 4 field. The integrity requirement is accomplished by verifying the digital signature. The hop count field is verified by comparing the result of the application of the hash function max hop count minus hop count times to the hash field with the value of the top hash field. Before the packet is re-broadcasted by the intermediate node the value of the hash field is replaced by the result of the calculation of the one-way hash of the field itself in order to account for the new hop. In SAODV route error messages (RERR) that are generated by nodes that inform their neighbors that they are not going to be able to route messages to specific destinations are secured using digital signatures. A node that generates or forwards a route error message cryptographically signs the whole message, except the destination sequence numbers.Although SAODV provides reasonable sec urity to MANETs routing, but it is still vulnerable to distance fraud attack 15 in which the forwarding node fails to increment the route metric because in SAODV there is no enforcement to do so. Further there is no method to detect the malicious nodes and DOS attacks because in SAODV it is assumed that DOS attacks are restricted to physical layer, but this assumption failed when colluding malicious nodes drop packets during the route discovery process.Security Aware Routing (SAR)SAR 16 (Security Aware Routing) is an extension to existing on demand routing protocols and used where nodes are grouped on the basis of trust level. In SAR each node has different security level which assigns them different trust levels. Two nodes can only communicate with each other if they have equal or greater trust values. If a node has lower security level it simply discards the packet. In case there is no node in the network with the desired level then communication cannot take place or we can say th at, that particular packet cant be forwarded unless its security level is lowered. By exploiting this condition a malicious node can attack at its level or at lower levels. Particularly in the context of Packet Dropping Attack, within a trust level, a malicious node or any other node which aims at saving its resources or intentionally launching a attack can successfully drop packets without being noticed and can get services from other nodes for forwarding its own packets. SAR also fails in the situations of secure routing in general because it only focuses on the situations in which certain groups are assumed to be trustworthy.ConclusionFrom the above discussion, we observe that all Secure Ad hoc routing protocols are still vulnerable to many attacks. Although proposed techniques provide security against external attacks, insider attacks are still an open issue in MANETs.Chapter 3Literature ReviewIntroductionMany solutions have been proposed to prevent selfishness in MANETs. The ma in goal of all the schemes proposed in the literature is to make decisions regarding trustworthy entities and to encourage behavior that leads to increasing trust. In this section we discuss some of the solutions presented in the literature in order to detect the malicious nodes in the network in context of packet dropping attack.Watchdog and PathraterIn 17 Marti el al, proposed a mechanism called as watchdog and pathrater on DSR6 to detect the misbehavior of nodes in MANETs. Nodes in this scheme operate in a promiscuous mode. The watchdog monitors one hop neighbor by overhearing the medium to check whether the next neighbor forwards the packet or not. It also maintains a buffer of recently sent packets. If a data packet remains in the buffer too long, the watchdog declares the next hop neighbor to be misbehaving. Every node that participates in the ad hoc network employs the watchdog functionality in order to verify that its neighbors correctly forward packets. When a node transmit s a packet to the next node in the path, it tries to promiscuously listen if the next node will also transmit it. Furthermore, if there is no link encryption utilized in the network, the listening node can also verify that the next node did not modify the packet before transmitting it . The watchdog of a node maintains copies of recently forwarded packets and compares them with the packet transmissions overheard by the neighboring nodes. Positive comparisons result in the deletion of the buffered packet and the freeing of the related memory. If a node that was supposed to forward a packet fails to do so within a certain timeout period, the watchdog of an overhearing node increments a failure rating for the specific node. This effectively means that every node in the ad hoc network maintains a rating assessing the reliability of every other node that it can overhear packet transmissions from. A node is identified as misbehaving when the failure rating exceeds a certain threshold band width. The source node of the route that contains the offending node is notified by a message send by the identifying watchdog. As the authors of the scheme note, the main problem with this approach is its vulnerability to blackmail attacks. The pathrater selects the path with the highest metric when there are multiple paths for the same destination node. The algorithm followed by the pathrater mechanism initially assigns a rating of 1.0 to itself and 0.5 to each node that it knows through the route discovery function. The nodes that participate on the active paths have their ratings increased by 0.01 at periodic intervals of 200 milliseconds to a maximum rating of 0.8. A rating is decremented by 0.05 when a link breakage is