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Vijaya Bhaskar .Ch, Nagaraju.M, Chaitanya Kumar.N / International Journal of Engineering
Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 2, Issue4, July-August 2012, pp.1227-1231
Review Of Attacks And Security Threats As Securing In Wireless
Ad Hoc Networks
Vijaya Bhaskar .Ch , Chaitanya Kumar.N, Nagaraju.M

Abstract

Security is an essential requirement in mobile ad devices. In this paper an effort has been made to evaluate
hoc network (MANETs). Compared to wired networks, various security threats.
MANETs are more vulnerable to security attacks due to the
lack of a trusted centralized authority and limited
resources. Attacks on ad hoc networks can be classified as 2. SECURITY REQUIREMENTS
passive and active attacks, depending on whether the
normal operation of the network is disrupted or not. The In any fixed or wireless network, the security is
study here proposes a theory in this paper based on incorporated at three stages: prevention, detection and cure.
Hashing as a tool. This scheme can make most of the on Key parts of prevention stage are authentication and
demand protocols secure. The study should help in making authorization. The authentication is associated with
protocols more robust against attacks and standardize authenticating the participating node, message and any other
parameters for security in routing protocols. meta-data like topology state, hop counts etc. Authorization
is associated with recognition. Where detection is the ability
Keywords: security threats, Attacks, secure routing, hash to notice misbehavior carried out by a node in the network,
function. the ability to take a corrective action after noticing
misbehavior by a node is termed as cure.
1. INTRODUCTION
Different possible attacks on ad hoc networks are
Wireless Ad Hoc networks interesting and eavesdropping, compromising node, distorting message,
challenging is its potential use in situations where the replaying message, failing to forward message, jamming
infrastructure support to run a normal network does not signals etc. The central issues behind many of the possible
exist. Some applications include a war zone, an isolated attacks at any level of security stage are authentication,
remote area, a disaster zone like earthquake affected area confidentiality, integrity, non repudiation, trustworthiness
and virtual class room etc. and availability.

Ad-hoc networks are self-organizing wireless There are several proposals available to solve these
networks, in which all end nodes act as routers. A Mobile issues, but are not comprehensive in nature as they target
Ad hoc Networks (MANET) consists of a set of mobile specific threats separately. Therefore there is a strong need
hosts within communication range and exchange the data to have an efficient security regime which can take care of
among themselves without using any preexisting all the aspects of security.
infrastructure. MANET nodes are typically distinguished
by their limited power, processing and memory resources 3. SECURITY THREATS
as well as high degree of mobility. In such networks, the
wireless mobile nodes may dynamically enter the network
and leave the network. Due to the limited transmission
range of wireless network nodes, multiple hops are usually
needed for a Node to exchange information with any other
node in the network.

It is very challenging for researchers to provide
comprehensive security for ad hoc networks with the
desired quality of service from all possible threats.
Providing security becomes even more challenging when
The two broad classes of network attacks are active attacks
the participating nodes are mostly less powerful mobile
and passive attacks.

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Vijaya Bhaskar .Ch, Nagaraju.M, Chaitanya Kumar.N / International Journal of Engineering Research
and Applications (IJERA) ISSN: 2248-9622 www.ijera.com

3.1 Passive Attack  Masquerading: The attacker impersonates an authorized
user and thereby gains certain unauthorized privileges.
A passive attack on a communications system is
one in which the attacker only eavesdrops; he may read  Replay: The attacker monitors transmissions (passive
messages he is not supposed to see, but he does not create attack) and retransmits messages as the legitimate user.
or alter messages. This contrasts with an active attack in
which the attacker may create, forge, alter, replace or  Message modification: The attacker alters a legitimate
reroute messages. Generally, the term "passive attack" is message by deleting, adding to, changing, or reordering it.
used in the context of cryptanalysis. For example,
wiretapping an unencrypted line is a passive attack.  Denial-of-service: The attacker prevents or prohibits the
normal use or management of communications facilities.
There are three passive attacks that will in theory break The consequences of these attacks include, but are not
any cipher except a one-time pad; variants of this work for limited to, loss of proprietary information, legal and
either block ciphers or stream ciphers: recovery costs, tarnished image, and loss of network service.

 brute force attack — try all possible keys Ad hoc networks face many problems due to which a
 algebraic attack — write the cipher as a system of consistent and secure network flow becomes challenging
equations and solve for the key task. Some of the issues associated are given below.
 code book attack — collect all possible
plaintext/cipher text pairs for a block cipher, or 1) Ad Hoc networks primarily being wireless have limited
the entire pseudorandom stream until it starts band-width in comparison to wired networks. Smaller
repeating for a stream cipher . packets are available to transfer data and it further
constraints to use lesser number of bits for security
An attack in which an unauthorized party gains purposes. It has been expected that this limitation will be
access to an asset and does not modify its content (i.e., eased with the advancement of hardware in future.
eavesdropping). Passive attacks can be either
eavesdropping or traffic analysis (sometimes called traffic 2) The participating nodes of an Ad Hoc networks usually
flow analysis). These two passive attacks are described as are mobile devices which have limited capabilities in terms
of processing power, memory size and battery backup. It
 Eavesdropping: The attacker monitors transmissions for makes the use of digital signature , as a security measure
message content. An example of this attack is a person less suitable as digital signatures are computation intensive.
listening into the transmissions on a network topology The use of digital signatures may also consume considerable
between two workstations or tuning into transmissions memory if digital signatures are appended by each node that
between a wireless handset and a base station. forwards the packet to its destination. Furthermore a PKI
infrastructure is not practical in case of Ad Hoc networks.
 Traffic analysis: The attacker, in a more subtle way, Other problem with use of digital signature is to maintain a
gains intelligence by monitoring the transmissions for certificate revocation list (CRL), in the absence of a central
patterns of communication. A considerable amount of server. The solution to this problem can be achieved by
information is contained in the flow of messages between using some light weight security arrangements only.
communicating parties.
3) The use of hashing techniques although offer efficient
3.2 Active Attack security measures but have been used relatively less.
Hashing technologies like MAC [4], HMAC [4], one way
An active attack attempts to alter or destroy the hash chains etc have mostly been used for authenticating
data being exchanged in the network there by disrupting routing and message information. The effectiveness of
the normal functioning of the network. hashing techniques depends on the way the collisions have
been treated.
An attack whereby an unauthorized party makes
modifications to a message, data stream, or file. It is
possible to detect this type of attack but it may not be
preventable. Active attacks may take the form of one of
four types masquerading, replay, message modification, LAYER Active Attacks comment
and denial-of-service (DoS). These attacks are summarized MAC LAYER Jamming attack The particular
as: ATTACKS class of DoS

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attacks. messages
NETWORK Wormhole attack severe threats TRANSPORT Session Hijacking spoofs the
LAYER to MANET LAYER attack victim‟s IP
ATTACKS routing ATTACKS address.
protocols, DSR SYN Flooding denial-of-
or AODV, the attack service attack
attack could APPLICATION Repudiation attack
prevent the LAYER
discovery ATTACKS
of any routes
other than 4. SECURE ROUTING
through the The routing protocols [1,2,3] with in ad hoc
wormhole. networks are more vulnerable to attacks as each device acts
Blackhole attack exploits the as a relay. Any tampering with the routing information can
mobile ad hoc be compromise the whole network. An attacker can
routing introduce rogue information with in routing information or
protocol, replay old logged or stored information.
consumes the The aim is to protect any information or behavior
intercepted that can update or cause a change to the routing tables on
packets cooperating nodes involved in an ad hoc routing protocol.
without any For completeness, timeliness and ordering are added to the
forwarding. list of desirable security properties that can eliminate or
Byzantine attack Creates routing reduce the threat of attacks against routing protocols.
loops. Techniques that can be used to guarantee these properties
Routing Attacks - are described in Table 1.
Routing Table
Overflow, Properties Techniques
Routing Table Timeliness Time stamping, Slotted
Poisoning, Time
Route Cache Ordering Sequence Numbering
Poisoning,
Rushing Attack Authenticity Password, Certificate
Packet Authorization Credential
Replication, Integrity Digest, Digital Signature
Resource Forward Confidentiality Encryption
consumption attack unnecessary
packets to the Non-Repudiation Chaining of Digital
victim node. Signature
IP Spoofing attack impersonates a
member by Table 1: Properties of secured routing
occupying IP
address. The following properties can be integrated into
State Pollution a malicious routing protocol messages to prevent attacks that exploit the
attack node gives vulnerability of unprotected information in transit:
incorrect  Timeliness: Routing updates need to be delivered in a
parameters in timely fashion. Update messages that arrive late may not
reply reflect the true state of the links or routers on the network.
Sybil attack impersonates They can cause incorrect forwarding or even propagate false
nonexistent information and weaken the credibility of the update
nodes information. Most ad hoc routing protocols have timestamps
Fabrication Injects huge and timeout mechanisms to guarantee the freshness of the
routes they provide.
packets into
the networks  Ordering: Out-of-order updates can also affect the
Modification make changes correctness of the routing protocols. These messages may
to the routing not reflect the true state of the network and may propagate

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false information. Ad hoc routing protocols have sequence Each of these desirable properties has a cost and
numbers that are unique within the routing domain to keep performance penalty associated with it. Some options such
updates in order. as enforcing access control to routing tables using
 Authenticity: Routing updates must originate from credentials and providing non repudiation by chaining
authenticated nodes and users. Mutual authentication is the signatures are extremely expensive and impractical to
basis of a trust relationship. Simple passwords can be used implement and enforce in a generalized routing protocol.
for weak authentication. Each entity can append a public
key certificate, attested by a trusted third party to claim its 5. PROPOSED SOLUTION - HASHING TECHNIQUES
authenticity. The certifying authority can implement a
password based login or a challenge-response mechanism Hash Function: Hashing techniques available are
to authenticate the identity in the first place. The receiving based on the concept of a hash function that transforms a
node can then verify this claim by examining the given input of arbitrary length to a value of a fixed length,
certificate. One of the problems in ad hoc networking is the called the hash value. The transformation is done in a
absence of a centralized authority to issue and validate manner that it is computationally infeasible to transform the
certificates of authenticity. hash value to the original value. Hash functions are very
 Authorization: An authenticated user or node is issued efficient as they do not involve heavy computations and
an unforgeable credential by the certificate authority. hence are applied in the area of security for message
These credentials specify the privileges and permissions authentication and integrity checks.
associated by the users or the nodes. Currently, credentials The problem with hash functions is collision.
are not used in routing protocol packets, and any packet Collision is a situation where a hash function generates the
can trigger update propagations and modifications to the same hash value for more than one different input values.
routing table. Collisions are possible in a hash function due to the fact that
 Integrity: The information carried in the routing updates it transforms an input of any length to an output of fixed
can cause the routing table to change and alter the flow of length, meaning a mapping from a larger set to a smaller set.
packets in the network. Therefore, the integrity of the The solution to this problem is achieved through the
content of these messages must be guaranteed. This can be adoption of appropriate collision resolution or avoiding
accomplished by using message digests and digital techniques. There can be three ways in which the collisions
signatures. can be handled: first by selecting a hash function that is
more and more collision resistant, second by putting the
 Non-repudiation: Routers cannot repudiate ownership
processing in an environment to minimize the chance of
of routing protocol messages they send. A major concern
collisions and third by resolving when the collision really
with the updates is the trust model associated with the
takes place. The choice of a hash function, its
propagation of updates that originate from distant nodes.
implementation and its associated collision resolution
Ad-hoc nodes obtain information from their neighbors and
technique depends on problem area that is being solved.
forward it to their other neighbors. These neighbors may
The popular examples of hashing functions found
forward it to other neighbors and so on. In most existing
to be used in different places are HMAC, MD5, SHA-1.
protocols, nodes cannot vouch for the authenticity of
One way hash chain: A unique way of using hash functions
updates that are not generated by their immediate
is „one way hash chain‟. This concept was firstly used to
neighbors. In order to preserve trust relationships, it
provide one time password authentication and later for one
becomes necessary to form a chain of routers (using
time use of digital cash. One way hash chain is the list of
signatures to protect integrity) and authenticate every one
values that are generated by applying a hash function on an
in turn, following the chain to the source. This is necessary
initial value repeatedly. Every value, except the initial one,
because trust relationships are not transitive. Alternative
is therefore generated by applying hash function to its
solutions that avoid chaining include the path attribute
previous value exactly one time. This way, any value from
mechanism developed for Secure BGP and secure distance
that list can be authenticated by providing the previous
vector routing.
value in the sequence as a key. Therefore the values of a
 Confidentiality: In addition to integrity, sometimes it
chain can be used in the reverse order of their generation.
may be necessary to prevent intermediate or non-trusted
The problem with hash chain is to synchronize the
nodes from understanding the contents of packets as they
authentication process with the revealing of the validating
are exchanged between routers. Encrypting the routing
keys. A message will be incorrectly invalidated if time
protocol packets themselves can prevent unauthorized
duration in which the validating key (the previous hash
users from reading it. Only routers that have the decryption
value from the hash chain) is being advertised is missed
key can decrypt these messages and participate in the
Many of the implementations of one way hash chains in ad
routing. This is employed when a node cannot trust one or
hoc network are based on TESLA[4] protocol which was
more of its immediate neighbors to route packets correctly,
initially developed for authenticating broadcast messages.
etc.

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Hash Trees: Hash tree is a tree of hash values that has protocols, but neither work discusses the mechanisms for
been built up on a set of some initial values. The lowest detecting the status of these links.
layer of the tree comprise of the initial values as the leaf
nodes, In the next layer of the tree the initial values are 7. CONCLUSION
individually converted to their corresponding hash values In this paper, the security threats for an ad hoc
while in the subsequent layers, the hash values are network has been analyzed and presented with the security
computed by utilizing more than one values of the lower objectives that need to be achieved. The paper represents the
layer. Eventually we have a top hash value representing the first step of research to analyze the security threats, to
root of the tree. The top hash value can be used to understand the security requirements for ad hoc networks,
authenticate any of the values within the tree. and to identify existing techniques, as well as to propose
new mechanisms to secure ad hoc networks. Hashing has
6. RELATED WORK been used as one of the tools. More skilled technical work
Most of the work done around using Hashing has to be done to deploy these security mechanisms in an ad
techniques is around authenticating messages and route hoc network and to investigate the impact of these security
table entries. Bayyaet al [3] demonstrate the use of hashing mechanisms on the network performance depending up on
as part of password based authenticated key exchange. The the requirements.
problems given in this protocol are (1) the need of a strong
shared secret (2) the need to constantly change the shared 8. REFERENCES
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