Analysis of wireless sensor networks

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 03 Issue: 03 | Mar-2014, Available @ http://www.ijret.org 160
ANALYSIS OF WIRELESS SENSOR NETWORKS: SECURITY, ATTACKS
AND CHALLENGES
Sunil Ghildiyal1
, Ashish Gupta2
, Musheer Vaqur3
, Anupam Semwal4
1
Assistant Professor, Department of CSE, Uttaranchal University, Prem Nagar, Dehradun (UK) India
2
Assistant Professor, Department of IT, Dev Bhoomi Institute of Technology, Dehradun (UK) India
3
Assistant Professor, Department of IT, Uttaranchal University, Prem Nagar, Dehradun (UK) India
4
Assistant Professor, Department of Mathematics, IEC University, Alal Nagar, Baddi, Solan (HP) India
Abstract
Recent advancements in MEMS technologies and development in the area of low power microcontrollers have resulted as
implementation of wireless sensor networks in real life problem solving in areas like traffic monitoring, patient monitoring ,
battlefield surveillance. These wireless sensors are very small in size and are operated at low power for low data rate applications.
WSN nodes include features like scalability, self-organizing, self-healing. WSN nodes face many challenges starting from deployment
till their life span which is dependent on very low battery strength. Since these nodes are operated in unattended environments, many
security threats are for them to survive. These nodes face variety of attacks at different layers of their architecture, ranging from
physical stealing, tempering to reprogramming. Applying any traditional security mechanism over wireless sensor nodes is also not
possible as those traditional algorithms or protocols consume very much processing and power due to their complexity. In this paper,
we have mentioned. This paper aims at reporting an initial introduction of WSN, WSN architecture, challenges and security threats
subsequently.
Keywords: Wireless, Sensor, Threat, Security, Power, Node
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1. INTRODUCTION
Wireless Sensor networks (WSN) is an emerging technology
that shows result oriented promise for many applications for
defense as well as mass public[1].WSN nodes are low power,
low cost smart devices having limited computing
resources[2]. In last few recent years, Wireless Sensor
Networks (WSNs) have gained worldwide attention
particularly with the proliferation in Micro-Electro-
Mechanical Systems (MEMS) technology which has
facilitated the development of sensors[3]. Rapid demand of
wireless sensor nodes indicates how these can be utilized in
different areas of real-life applications. Main aim is to
interpret, observe and handle the WSN node data at base
station (BS). WSNs form an ad-hoc network that operate with
nominal or no infrastructure. WSNs merge a wide range of
information technology that spans multiple computer
hardware vendors, software, networking and programming
methodologies. WSNs make it possible to perceive what takes
place in the physical world in ways, was not previously
possible [4].
2. REVIEW OF LITERATURE
Set of challenges in sensor networks are diverse and focused
on supporting multi-hop communication, data management,
geographic routing challenges in networks and monitoring and
maintenance of such dynamic, resource-limited WSNs.
Ganeshan et al.[5] Current surveys and forecast predict that
the number of wireless devices is going to increase
tremendously. These wireless devices can be computers of all
kinds, notebooks, net-books, Smart-phones and sensor nodes
that evolve into real- world scenarios forming a ”Real-World-
Internet” in the future. Horst Hellbruck et al.[6] In WSNs.
application domains are diverse due to availability of tiny
micro sensors with low power wireless communications.
These can be densely deployed with their auto configuration
features in different areas of application to solve real world
problems. Kalitha et al.[7]. Wireless sensors are not isolated
from attacks easily. They are prone to physical attacks. Any
traditional security algorithm is not applicable due to resource
constraint. Kavitha et al.[8]
3. CHARACTERISTICS OF WSN
The main characteristics of a WSN include: WSN are getting a
lot of popularity day by day due to their low costing solutions
to variety of real world applications, many other favoring
factors of WSN use are low power consumption constraints
for nodes: portability, unattended operation, using batteries or
energy harvesting, ability to withstand bad environmental
conditions, having dynamic network topology, to cope with
node malfunctioning and failures, Mobility of deployed nodes,
Heterogeneity of nodes, Scalability, at the time of deployment
and after deployment, Easy use.

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4. THREAT MODEL
In WSN, threats are from outside the network and within the
network. If attacks are from the nodes of the native network
then it is much harmful. Also, it is quite difficult to find out
the malicious or compromising node within the native
network. Another classification of the attacks may be passive
and active where passive attacks don‟t modify or alter the data
as active attacks do. If the opponent attack by using similar
capacity nodes for network penetration it is called mote class
attack but when powerful devices like laptop are used to
penetrate the network then such attack is called laptop attack.
5. WSN SECURITY GOALS
Traditional security goals for an ad-hoc network and specific
to the WSN security goals can be classifies in two categories
as primary and secondary [9]. The primary goals are known as
standard security goals such as Confidentiality, Integrity,
Authentication and Availability (CIAA). The secondary goals
are Data Freshness, Self-Organization, Time Synchronization
and Secure Localization.
5.1 Primary Goals:
5.1.1 Data Confidentiality
Confidentiality means to reveal the data to the authorized
persons only not to everyone in the networks. It is the ability
to conceal messages from a passive attacker so that any
message communicated via the sensor network remains
confidential.
5.1.2 Data Integrity
It ensures the data during transition is not altered, tempered by
an unauthorized one may be an attacker. Even if the network
has confidentiality measures, there is still a possibility that the
data integrity has been compromised by alterations. If any
malicious node is present in the network or medium of
transmission is damages, then also integrity may get affected
[10].
5.1.3 Data Authentication
Authentication ensures the reliability of the message by
identifying its origin. In WSN attacks, adversaries can also
inject additional false packets [11]. Data authentication
verifies the identity of the senders and receivers.
5.1.4 Data Availability
It is the ability of a node to ensure the availability of the
resources for use. It also ensures the network for message
communications. This goal of security ensures the
functionality of the network. However failure of central hub or
cluster head may make a node unavailable for use.
5.2 Secondary Goals:
5.2.1 Data Freshness
It ensures that data contents are recent and there no replay of
any old content. Even though Integrity and confidentiality is
there, data freshness is to be checked separately.
5.2.2 Self-Organization
Each node must be self organized, self configured while
joining its ad-hoc nature networking environment. Nodes must
be independent and must have self-healing capabilities even in
critical situations. There is no any fixed infrastructure for
WSN implementation, so nodes must their selves adapt the
topology and deployment strategy.
5.2.3 Time Synchronization
Many WSN applications demand some form of time
synchronization for execution. Sensors organized in group
collaboration may require time synchronization for application
tracking.
5.2.4 Secure Localization
Sensors may get displaced while deploying them or after a
time interval or even after some critical displacement incident.
The utility of a sensor network will rely on its ability to
accurately and automatically locate each sensor in the
network. A sensor network designed to locate faults will
require precise location in order to detecting fault location.
6. ATTACKS ON SENSOR NETWORKS
Broadcast nature of communication is WSN is vulnerability
for them. Subsequently, wireless sensor networks have an
additional threat from their physical deployment as these
nodes are not physically protected. Mainly, attacks are
classified as active attacks and passive attacks. All the
classical techniques of attacks will also be applied on WSN.
But due to limited capability of node, some specific attacks
can also damage node and network subsequently. For
examples an adversary can eavesdrop on the communication,
perform traffic analysis of the observed network behavior, can
replay the communication traffic later on. [12].
The attacks of WSN can be classified into two categories:
invasive and non-invasive. Non-invasive attacks generally
target to timings, power and frequency of channel. Invasive
attacks target to availability of service, transit of information,
routing etc. In DoS attack, hacker tries to make service or
system inaccessible.

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6.1 Attacks at Physical Layer
6.1.1 Jamming
Jamming attacks leads to the interference by identical radio
frequencies used by the network nodes. The adversary can
either disrupt entire network or a particular small portion of it.
It depends on the power of jamming nodes distributed nearby
the network. Jamming is of various types Constant, Deceptive,
Random and Reactive[13]. Handling the jamming at MAC
layer needs to control the requests which may exhaust the
resources by ignoring them. However network layer also deals
with jamming by mapping jamming area in the network or in
surrounding routing area.
6.1.2 Tempering
As nodes are operated in unattended areas, attacker may
physically temper the node and can compromise with them. It
is not possible to control hundreds of nodes spread over large
area. Attacker may extract the sensitive information like
cryptographic keys from node by damaging it.
6.2 Attacks at Link Layer
6.2.1 Exhaustion (Continuous Channel Access)
In this attack, attacker may disrupt the channel by
continuously requesting and transmitting over it. It results in
starvation for channel access for other nodes. It is usually done
by sending a large numbers of RTS (Request to Send) packets
over channel, leading multiple collisions and draining out the
nodes of their power.
6.2.2 Collision
Collision occurs when two nodes intend for simultaneous
transmission on same frequency channel. If the packets
collide, a small change in packet will take place which will be
encountered as mismatch at the time of checksum at receiving
end and hence packets will be discarded, to be re transmitted.
6.2.3 Unfairness
Unfairness is referred as repeated collision based or
exhaustion based attacks or an abusive use of cooperative
MAC layer priority mechanisms. Also may be called as a
weaker form of DoS. This threat may not entirely prevent
legitimate access to the access channel but it could degrade
service in order to gain an advantage such as causing other
nodes in a real-time MAC protocol to miss their transmission
deadline.
6.3 Attack s at Network Layer
6.3.1 False Routing or Spoofed, Altered, Replayed
Routing Information
Such attacks primarily focus on routing protocols mainly for
routing information. While nodes exchanging the routing
information, by changing the routing information by a
malicious node, it is possible to change the routing of entire
WSN structure or its any network partition. This can be done
by altering or changing the routing information, by shortening
or extending the route information in the routing table or by
generation of false error messages.
6.3.2 Selective Forwarding
Fundamental principle of WSN is „Multi-hop”. It means that
sensor nodes will forward the entire message to next node in
line what they have received. In this attack, nodes drop few
messages instead of forwarding everything of what they have
received. Attacking nodes deny routing some messages and
drop them. If all the packets are denied for forwarding by
anode after receiving, is called black hole attack.
6.3.3 Sinkhole Attacks
In this attack attackers seem to be more attractive to its
surrounding nodes by forging the routing information. Main
aim of attacker is to tempt all the nodes in close proximity,
constructive a figurative sinkhole. It results in the malicious
node to be most chosen for data forwarding through it by other
surrounding nodes.
6.3.4 Sybil Attack
In this attacker attacks a single node in the network with a
malevolent code masked with multiple identities. Then this
node behaves as polymorphic. Its multiple identities mislead
to all other nodes. Some of such identities are decreasing
topology maintenance schemes, disparity in storage, disparity
in routing.
6.3.5 Wormhole
Wormhole is referred as low latency link between two
portions of a WSN network over which an attacker replays
network messages [14]. Here an adversary convinces the
nodes which are multi hop away that they are closer to the
base station (BS).The wormhole attack usually engage two
different and far away malevolent codes conspire to minimize
their remoteness from each other by replaying packets next to
an out-of-reach channel, is only available to attacker.
6.3.6 Hello Flood
Malicious nodes sometime can cause of immense traffic of
useless messages. It is known as flooding. Malicious nodes,
sometime replay some broadcast traffic which is useless but

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congest the channel. In hello flood type attack, attackers use
very high power RF transmitters to handle the large area of
nodes into trusting that they are neighbors of it. Attacker will
broadcast a false superior route so that other nodes will
attempt very far from it in RF distance.
6.4 Attacks at Transport Layer
6.4.1 Flooding
Any protocol which maintain state at either end, it has to face
a problem called flooding. Attacker may repeatedly establish
new connection requests until the resources are exhausted,
which were required by each connection or reached maximum
limit. Under such conditions, further legitimate requests will
be ignored. Limiting the number of connections prevents from
complete resource exhaustion.
6.4.2 De-synchronization
Connection between two endpoints can be disrupted by de-
synchronization. In this attack, the adversary repeatedly forges
messages to either or both endpoints. For example, there may
be requests for retransmissions of missed frames by the
repeated spoof messages. If timed correctly, an attacker may
degrade the functionality, capability of end hosts by
retransmission of frames unnecessarily. It causes endpoints to
waste the energy for attempt to recover from errors which
never really exist.
7. WSN CHALLENGES
WSNs. are specific real world problem solving methods not
merely as combination of sensor and electronics circuit along
with wireless communication linking capability. Many
challenges on WSN are to be considered before applying
wireless sensors to a particular application, solving a problem
7.1 Resource Constraints
Wireless sensors are low costing, low power tiny devices
which may handle and process a limited amount of data , low
amount of data transmission capability since transmission
require a significant amount of power, very low battery life
and memory space. Cause of limited transmission capability
bandwidth of channel is also limited resulting limiting radio
range of channel. Since it is not possible to replace or recharge
the battery of sensor nodes after deployed once, conservation
of energy is also to be considered as main factor before
designing any software routine or protocol for WSNs.
7.2 Platform Heterogeneity
Wireless sensor network (WSN) may run different
applications for different tasks, such as event detection,
localization, tracking, or monitoring. Different types of sensor
node are therefore required, and to handle heterogeneous
WSNs with a large number of these different sensor nodes,
comprehensive heterogeneity management architecture is also
necessary. When deployed in large networks, sensors, may
behave differently due to environment they are deployed in
terms of infrastructure or networking technologies. Hence
capability and functionality of sensor node may vary.
7.3 Dynamic Network Topology
WSNs may consist of mobile nodes instead of static nodes.
Many application demand node mobility such as intelligent
transportation, planetary exploration, and animal control. In
such solutions new nodes are to added with sleep or
replacement on existing nodes. Even after a time period many
node me die due to power exhaust. These factors lead to
network topology of WSNs to be dynamic, not static. This
dynamic topology results in uncertainty of QoS in WSNs.
7.4 Mixed Traffic
Sensor nodes are randomly deployed at large scale to fulfill
the requirements of multiple application over heterogeneity.
Those application may use or handle the data which are
different in nature like as streaming, periods. To meet out such
mixed traffic demands WSNs have to be scalable as needed by
the applications. However some extra sensor may be required
to detect such uncommon properties of applications. Variety
of detected inputs or data may vary in size, magnitude,
resulting handling of this mixed traffic generated from input of
different types of sensors.
7.5 Sensor Deployment and Location:
In WSNs. applications based geographical constraints; require
random deployment of sensors in an affected area like as
avalanche prone area, volcano prone area. Since sensors are
scattered in such critical areas from a distance to be deployed
in unknown manner, their position after deployment is
uncertain, resulting drastic variance in topology they have
formed their selves after deployment. Even some sensor may
get damaged or lost during deployment.
7.6 Security
Wireless medium of linking between the node itself is a
vulnerability to the architecture due to its easy access to all.
Any standard cryptographic strategy or similar one can also
not be applied directly to the sensor nodes due to their
execution complexity and required many resources like space,
memory and energy.
8. WSN SECURITY COMPLICATIONS
Several constraints of the WSN architecture and their low
capabilities make security issue complicated in WSN.
Physical stealing or capture is one of the issue while securing
wireless sensor network. As these network use open air
medium for communication, which is easy to penetrate is
another security implementation issue with WSN. Any

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attacker may inject malicious information or data easily into
the wireless network. Many anti-jamming techniques are
available to eliminate attacks like jamming but those are very
complex, energy and processing consuming, hence difficult to
be implemented on tiny sensor nodes. Sensors are very tiny,
low powered and low processing capable hence more
susceptible for DoS attacks. Since sensor nodes form ad-hoc
network, attacker may get access to the network easily and can
damage the infrastructure.
9. CONCLUSIONS
Limited capability and less capable hardware of WSN nodes
make them more susceptible for attacks.
Any traditional security mechanism can also not be applied at
any level of WSN architecture to prevent for its respective
attacks as nodes will not be able to execute same mechanism
or will be exhausting their power and life. Large scale
deployment for tightening the security measures are also not
possible over low capability nodes. If security is maximized
then consumption of resources will increase, result of node‟s
life exhaust. Since sensor nodes usually have severely
constrained, asymmetric cryptography is often too expensive
for many applications. Thus, a promising approach is to use
more efficient symmetric cryptographic alternatives.
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