Determine the Security Issues in Wireless Sensor Networks
Prof.Shashikant B. Ahire.
Assistant Professor of Master of Computer Application Department,
A.C.Patil College of Engineering, Kharghar-410210,
Navi-Mumbai, Maharashtra
sbahire.acpce@gmail.com
Mr. Pankaj Pimple
Student of of Master of Computer Application Department,
A.C.Patil College of Engineering, Kharghar-410210,
Navi-Mumbai, Maharashtra
pppankaj39@gmail.com
Abstract--Wireless Sensor Network (WSN) is an emerging
technology which shows a very good number of valid futuristic
applications both for common people and military. As wireless
sensor networks continue to grow, so does the need for
effective security mechanisms. The basic idea of asensor
network is to disperse tiny sensing devices that are capable of
sensing some changes of incidents/parameters and
communicating with other devices. The inclusion of wireless
communication technology incurs various types of security
threats. This paper introduces determination of security issues
in wireless sensor network, by identifying various threats and
the research issues some security measures in the WSN is
proposed. In this paper I introduce different security
considerations for accessing efficient security in a real time
security processes. I also discuss the security for ensuring
layered and robust security in wireless sensor networks.
pressure, etc. and the corresponding data are transmitted
through the network to a main location.The more modern
networks are bi-directional, also enabling control of sensor
activity. The development of wireless sensor networks was
motivated by military applications such as battlefield
surveillance; today such networks are used in many
industrial and consumer applications, such as industrial
process monitoring and control, machine health monitoring,
and so on.
Basic Idea about WSN
The WSN (Figure 1) is built of "nodes" – from a few
hundreds or even thousands, where each node is connected
to one or more sensors.
Index Terms-Wireless Sensor Network (WSN), Security.
I. INTRODUCTION
Wireless Sensor Networks:Wireless Sensor Network is an
ad hoc(created or done for a particular purpose as necessary)
network that consists of a number of resource constrained
devices spread across some geographical area to monitor the
physical or environmental conditions, such as temperature,
sound, vibration, pressure, motion or pollutants detection
and for the surveillance in the military applications.
Now-a-days sensor networks are used in many industrial
and civilian application areas including industrial process
monitoring and control, health monitoring, environment and
habitat monitoring, healthcare applications, home
automation, traffic controls, etc.
Security:
Security means to provide the protection against the danger,
loss and criminals but in the networks it is the Protection of
information from theft, corruption or natural disaster while
allowing the information to be accessible by the intended
users.
A wireless sensor network (WSN) consists of spatially
distributed autonomous sensors to monitor physical or
environmental conditions such as temperature, sound,
Fig.1 WSN
Each such sensor network node has typically several parts:
a radio frequency trans receiver with an internal antenna or
connection to an external antenna, a microcontroller, an
electronic circuit for interfacing with the sensors and an
energy source, usually a battery or an embedded form of
energy harvesting.
A sensor node might vary in size from that of a shoebox
down to the size of a grain of dust, although functioning
"motes" of genuine microscopic dimensions have yet to be
created. The cost of sensor nodes is similarly variable,
ranging from a few thousands of rupees, depending on the
complexity of the individual sensor nodes. Size and cost
constraints on sensor nodes result in corresponding
constraints on resources such as energy, memory,
computational speed and communications bandwidth.
WSN Topologies
WSN nodes are typically organized in one of three types of
network topologies. In a star topology, each node connects
directly to a gateway. In a cluster tree network, each node
connects to a node higher in the tree and then to the
gateway, and data is routed from the lowest node on the tree
to the gateway. Finally, to offer increased reliability, mesh
networks feature nodes that can connect to multiple nodes in
the system and pass data through the most reliable path
available. This mesh link is often referred to as a router (see
Figure 2).
Figure 2. Common WSN Network Topologies
II. APPLICATIONS OF WSN
Wireless Sensor Networks (WSN) has off late, found
applications in wide-ranging areas. In this section I list some
of the prominent areas of applications of WSN. The list
would bevery lengthy if I exhaust all the areas of WSN
applications. Therefore, in this paper only handful
applications are provided.
>The military applications of sensor nodes include
battlefield surveillance and monitoring, guiding systems
ofintelligent missiles and detection of attack by weapons of
massdestruction.
>The Medical Application: Sensors can beextremely
useful in patient diagnosis and monitoring. Patientscan wear
small sensor devices that monitor their physiologicaldata
such as heart rate or blood pressure.
>Environmental monitoring: It includes traffic,habitat,
Wild fire etc.
>Industrial Applications: It includes industrialsensing and
diagnostics. For example appliances, factory, supplychains
etc.
>Infrastructure Protection Application: Itincludes power
grids monitoring, water distribution monitoringetc.
>Miscellaneous Applications: Sensors will soonfind their
way into a host of commercial applications at home andin
industries. Smart sensor nodes can be built into appliances
athome, such as ovens, refrigerators, and vacuum cleaners,
whichenable them to interact with each other and be remotecontrolled.
III. SECURITY ISSUES IN WSN
Security issues in sensor networks depend on the need to
know what we are going to protect. Four security goals in
sensor networks which are Confidentiality, Integrity,
Authentication and Availability. Confidentiality is the
ability to conceal message from a passive attacker, where
the message communicated on sensor networks remain
confidential. Integrity refers to the ability to confirm the
message has not been tampered, altered or changed while it
was on the network. Authentication Need to know if the
messages are from the node it claims to be from,
determining the reliability of message’s origin. Availability
is to determine if a node has the ability to use the resources
and the network is available for the messages to move on.
Freshness implies that receiver receives the recent and fresh
data and ensures that no adversary can replay the old data.
This requirement is especially important when the WSN
nodes use shared-keys for message communication, where a
potential adversary can launch a replay attack using the old
key as the new key is being refreshed and propagated to all
the nodes in the WSN. To achieve the freshness the
mechanism like nonce or time stamp should add to each
data packet.
Why is security necessary in WSN? The reasons are
many. First of all Wireless networks are vulnerable to
security attacks due to the broadcast nature of the
transmission medium. Furthermore, wireless sensor
networks have an additional vulnerability because nodes are
often placed in a hostile or dangerous environment where
they are not physically safe.
Attacks on WSNs can be classified from two different
levels of views:1. Attack against security mechanisms.
2. Attack against basic mechanisms (like routing
mechanisms).
In many applications, the data obtained by the sensing nodes
needs to be kept confidential and it has to be authentic. In
the absence of security a false or malicious node could
intercept
private information, or could send false messages to nodes
in the network. The major attacks are: Denial of Service
(DOS), Wormhole attack, Sinkhole attack, Sybil attack,
Selective Forwarding attack, Passive information gathering,
Node capturing, false or malicious node, Hello flood attack
etc. In this section a brief overview on these attacks are
presented.
> Denial of Service (DoS)
It occurs by the unintentional failure of nodes or malicious
action. The simplest DoS attack tries to exhaust the
resources available to the victim node, by sending extra
unnecessary packets and thus prevents legitimate network
users from accessing services or resources to which they are
entitled.
DoS attack is meant not only for the adversary’s attempt to
subvert, disrupt, or destroy a network, but also for any event
that diminishes a network’s capability to provide a service.
In wireless sensor networks, several types of DoS attacks in
different layers might be performed. At physical layer the
DoS attacks could be jamming and tampering, at Data link
layer, collision, exhaustion, unfairness, at network layer,
neglect and greed, homing, misdirection, black holes and at
transport layer this attack could be performed by malicious
flooding and asynchronization.
>The Wormhole attack
One node in the network (sender) sends a message to
another node in the network (receiver node).Then the
receiving node attempts to send the message to its
neighbours. The neighbouring nodes think the message was
sent from the sender node (which is usually out of range), so
they attempt to send the message to the originating node,
but it never arrives since it is too far away.
Wormhole attack is a significant threat to wireless sensor
networks, because, this sort of attack does not require
compromising a sensor in the network rather, it could be
performed even at the initial phase when the sensors start to
discover neighbouringinformation.
the traffic from a particular area through a compromised
node, creating a metaphorical sinkhole with the adversary at
the centre. Sinkhole attacks typically work by making a
compromised node look especially attractive to surrounding
nodes with respect to the routing algorithm.
Sinkhole attacks are difficult to counter because routing
information supplied by a node is difficult to verify.
As an example, a laptop-class adversary has a strong power
radio transmitter that allows it to provide a high-quality
route by transmitting with enough power to reach a wide
area of the network.
>Passive Information Gathering
An intruder with an appropriately powerful receiver and
well-designed antenna can easily pick off the data stream.
Interception of the messages containing the physical
locations of sensor nodes allows an attacker to locate the
nodes and destroy them. Besides the locations of sensor
nodes, an adversary can observe the application specific
content of messages including message IDs, timestamps and
other fields.
> Node Capturing
Wormhole attacks are difficult to counter because routing
information supplied by a node is difficult to verify.
A particular sensor might be captured, and information
stored on it might be obtained by an adversary.
> The Sybil attack
> False or Malicious Node
In this attack, a single node i.e. a malicious node will appear
to be a set of nodes and will send incorrect information to a
node in the network.
The incorrect information can be a variety of things,
including position of nodes, signal strengths, making up
nodes that do not exist.
Most of the attacks against security in wireless sensor
networks are caused by the insertion of false information by
the compromised nodes within the network.
>Hello flood attacks
Authentication and encryption techniques can prevent an
outsider to launch a Sybil attack on the sensor network.
However, an insider cannot be prevented from participating
in the network, but he should only be able to do so using the
identities of the nodes he has compromised.
Public key cryptography can prevent such an insider attack,
but it is too expensive to be used in the resource constrained
sensornetworks.
> Selective Forwarding attack
It is a situation when certain nodes do not forward many of
the messages they receive. The sensor networks depend on
repeated forwarding by broadcast for messages to propagate
throughout the network.
> Sinkhole attacks
In a sinkhole attack, the adversary’s aim is to lure nearly all
The Hello flood attacks can be caused by a node which
broadcasts a Hello packet with very high power, so that a
large number of nodes even far away in the network choose
it as the parent. All messages now need to be routed multihop to this parent, which increases delay.
IV.DEFENSE MECHANISMS
This section highlights the preventive measures of all the
attacks mentioned above.It is to be noted that the list would
be very vast if I try to exhaustively list all the preventive
measures. So the list is restricted to only a handful of the
solutions.
> DOS prevention
The mechanisms to prevent DoS attacks include payment
for network resources, pushback, strong authentication and
identification of traffic. One security technique uses
authentication streams to secure the reprogramming process.
This divides a program binary into a series of messages,
each of which contains a hash of the next message. This
mechanism ensures that an intruder can’t hijack an ongoing
program transmission, even if he or she knows the hashing
mechanism. This is because it would be almost impossible
to construct a message that matches the hash contained in
the previous message. A digitally signed advertisement,
which contains the program name, version number, and
hash of the first message, ensures that the process is
securely initiated.
We can defeat many threats using existing encryption and
authentication mechanisms, and other techniques (such as
identifying jamming attacks) can alert network
administrators of ongoing attacks or trigger techniques to
conserve energy on affected devices.
>Wormhole attack prevention
The mechanism to combat the wormhole attack include,
DAWWSEN, a proactive routing protocol based on the
construction of a hierarchical tree where the base station is
the root node, and the sensor nodes are the internal or the
leaf nodes of the tree. A great advantage of DAWWSEN is
that it doesn’t require any geographical information about
the sensor nodes, and doesn’t take the time stamp of the
packet as an approach for detecting a wormhole attack,
which is very important for the resource constrained nature
of the sensor nodes.
>Sybil prevention
The mechanisms to prevent against Sybil attacks are to
utilize identity certificates. The basic idea is very simple.
The setup server, before deployment, assigns each sensor
node some unique information. The server then creates an
identity certificate binding this node’s identity to the
assigned unique information, and downloads this
information into the node. To securely demonstrate its
identity, a node first presents its identity certificate, and
then proves that it possesses or matches the associated
unique information. This process requires the exchange of
several messages. Merkle hash tree can be used as basic
means of computing identity certificates. The Merkle hash
tree is a vertex-labelled binary tree, where the label of each
non-leaf vertex is a hash of the concatenation of the labels
of its two child vertexes. The primary path of a leaf vertex
is the set of vertexes on the path from the leaf to the root
of the tree. The authentication path consists of the siblings
of the vertexes on this primary path. Given a vertex, its
authentication path, and the hash function, the primary
path can then be computed, up to and including the root of
the tree. This computed value of the root can then be
compared with a stored value, to verify the authenticity of
the label of the leaf vertex.
>Passive information gathering prevention
To minimize the threats of passive information gathering,
strong encryption techniques need to be used.
> Node capture prevention
If a node has been compromised then how to exclude that
node and that node only, from the sensor network is at
issue. This issue is solved by Localized Encryption and
Authentication protocol (LEAP). LEAP (localized
encryption and authentication protocol) is an efficient
protocol for inter-node traffic authentication. This protocol
relies on a key sharing approach that authorizes in-network
processing, and at the same time mitigates a number of
possible attacks.
> False or Malicious Node prevention
This attack basically should be checked in the Routing
layer itself. Details pertaining to the preventive measures
for „false node‟ attack are out of the scope of this paper.
>Hello flood attacks prevention
This can be avoided by checking the bidirectional of a
link, so that the nodes ensure that they can reach their
parent within one hop.
>Selective Forwarding attack prevention
Multipath routing can be used to counter these types of
selective forwarding attacks. Messages routed over paths
whose nodes are completely disjoint are completely
protected against selective forwarding attacks involving at
most compromised Allowing nodes to dynamically choose a
packet‟s next hop probabilistically from a set of possible
candidates can further reduce the chances of an adversary
gaining complete control of a data flow.
>Sinkhole attacks prevention
Such attacks are very difficult to defend against. One class
of protocols resistant to these attacks is geographic routing
protocols. Geographic protocols construct a topology on
demand using only localized interactions and information
and without initiation from the base station.
V. CONCLUSION
All of the previously mentioned security threats, the Hello
flood attack, wormhole attack, Sybil attack, sinkhole attack,
serve one common purpose that is to compromise the
integrity of the network they attack. Also In the past, focus
has not been on the security of WSNs, but with the various
threats arising and the importance of data confidentiality,
security has become a major issue. Although some solutions
have already been proposed, there is no single solution to
protect against every threat. In our paper I mainly focus on
the security threats in WSN. I’ve presented the summery of
the WSNs threats affecting different layers along with their
defense mechanism. I conclude that the defense mechanism
presented just gives guidelines about the WSN security
threats; the exact solution depends on the type of
application the WSN is deployed for. There’re many
security mechanisms which are used in „layer-by-layer‟
basis as a security tool. Recently researchers are going for
integrated system for security mechanism instead of
concentrating on different layers independently. Through
this paper I’ve tried to present the most common security
threats in various layers and their most probable solution.
ACKNOWLEDGEMENT
I would gratefully and sincerely appreciate my supervisor:
Assistant Prof. Shashikant B. Ahire. Their inspiring
guidance, rich experience and sustained encouragement
enabled me to develop an intensive understanding of my
research area. Without the generous help of my supervisor,
this work would not have been possible. I am honored to
have Prof. Shashikant B. Ahire from A.C.Patil College as
my opponent. I thank her for her kind support and helpful
suggestions during the discussions in my MCA.
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