The document outlines the key topics in wireless sensor network (WSN) security. It begins with an introduction to WSN specifications, constraints, security requirements and threats. It then discusses various denial of service attacks against WSN availability, as well as threats against data secrecy. Potential countermeasures are also reviewed, along with defenses against different privacy attacks. Finally, important WSN security protocols are mentioned. The overall document provides an overview of important WSN security concepts and challenges due to the unique constraints of sensor networks.
3. 3
WSN Specification Review
High
number of nodes
High-density deployment of nodes
Vast and various applications
Energy, memory and processing limit
No communication Infrastructure
Remote area deployment
Being Unattended after deployment
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4. 4
WSN Security Concerns
How
to secure against physical attacks in
unattended deployments?
How to secure in accordance with WSN
constraints?
How to adapt security mechanisms in
other networks to WSN?
How to design secure routing, clustering,
MAC, data aggregation and locationing
protocols?
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5. 5
WSN Constraints Review
Energy
constraint
Memory constraint
Unreliable communication
High latency
Remote intermittent support
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6. 6
Energy Constraint
Energy
Transducer unit
Communication unit
Processing unit
To
need :
communicate 1 bit
800 to 1000 instructions
Communication
consumes the most.
Security mechanisms impose
communication overhead and more cost.
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7. 7
Memory Constraint
Memory
Type :
Flash : Program code
RAM: Running application, Processing and
aggregated data
Not
enough space to support security
mechanisms
SMART DUST: 4KB for Tiny OS, Just 4.5KB to…
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8. 8
Unreliable Communication
Channel
destroying nature
Noise, Interference, fading
Congestion
in nodes
Collision
More
overhead to assure communication
Less space remained to security
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9. 9
High Latency
Multi
hop connection-less routing
Congestion and need to retransmission
But in Security synchronization is important
Security log Review
Security log correlation and analysis
Key management
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10. 10
Remote Intermittent Support
Remote
deployment
Not management and maintenance for
long periods
They are exposed to physical attacks
They need to be secured against that
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11. 11
WSN Security Entities
What
Data
Resources
From
what to protect ?
Attacks
Anomalies
How
to Protect ?
to protect ?
Mechanisms and protocols
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13. 13
Security Requirements(Cont..)
Confidentiality: Data understood just at
authorized node.
Integrity : No change or modification at
intermediate nodes.
Availability : WSN service Availability in spite
of security breaches like DoS attack.
Freshness : Data is not replayed or replicated.
Self organization and healing: Protocols
dynamicity not only in … but also in security
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14. 14
Security Requirements(Cont..)
Secure
Localization : where that is critical
the protocols must be robust enough like
Verifiable Multilateration.
Authentication : Ensures integrity
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15. 15
WSN Security Threats
Against
Availability: They are generally
DoS Attacks.
Against Secrecy and Authentication:
Attacks like eavesdropping, IP spoofing
and Packet Replay.
Against Service Integrity : Make the
network accept false data values.
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16. 16
Threats Against Availability
DoS
An event to reduce a network’s capacity
to perform an expected function.
Common defense mechanisms need large
overhead and not suitable for WSN.
DoS
attacks in general:
attack in WSN:
They are considered in different layers
Defense mechanisms are developed
specially
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17. 17
DoS Attack in WSN
Physical
Jamming : continuous, intermittent, distributed
Tampering : the node or its function change
Data
Layer:
Link Layer:
Intentional Collision: Back-off time increase
Resource Exhaustion: impose retransmission
Unfairness: degradation of real-time
applications/ weak form of DoS attack
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19. 19
Network Layer DoS
Spoofing Routing Information:
An attacker may spoof, alter, or replay
routing information to disrupt traffic in the
network.
These disruptions include :
creation of routing loops
attracting or repelling network traffic from
selected nodes
extending or shortening source routes
generating fake error messages
causing network partitioning
increasing end-to-end latency
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20. 20
Network Layer DoS
Selective Packet Forwarding:
Multihop Nets like WSN require accurate forwarding
An attacker may compromise a node in such a way
that it selectively forwards some messages and drops
others.
Sinkhole:
an attacker makes a compromised node look more
attractive to its neighbors by forging the routing
information
Facilitates the selective forwarding
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21. 21
Network Layer DoS
Sybil:
One node presents more that one identity in a network
To defeat objective of redundancy mechanisms in
distributed data storage systems in peer to peer Nets.
effective against routing algorithms, data aggregation,
voting, fair resource allocation, and foiling misbehavior
detection.
Wormhole:
Creating low latency link between two portions of a network
over which an attacker replays network messages via :
Single node connecting two adjacent non-neighboring nodes.
Pairs of nodes in two portion of the network (Facilitates Sinkhole).
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22. 22
Network Layer DoS
Hello
Flooding:
the attacker node falsely broadcasts a shorter route to the
base station through high power hello packet transmission.
All nodes in spite that of being out of the radio range of the
attacker, attempt to send packets to it.
It facilitates Sinkhole attack.
Acknowledge
Spoofing:
attacking node may overhear packet transmissions from its
neighboring nodes and spoof the acknowledgments
The attacker is able to disseminate wrong information about
the status of the nodes
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23. 23
Transport Layer DoS
Flooding:
Any protocol with status keeping at connection end is
vulnerable to this.
An attacker may repeatedly make new connection
request.
The resources required by each connection are
exhausted or reach a maximum limit.
Further legitimate requests will be ignored
De-synchronization:
Disruption of an existing connection .
Accurately timed, repeatedly spoof messages to an end
host causing the host to request the retransmission of
missed frames.
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25. 25
Threats Against Secrecy
Node
Replication :
An attacker attempts to add a node to an
existing WSN by replication (i. e. copying) the
node identifier of an already existing node in
the network.
Leads to network partitioning, communication
of false sensor readings.
Accessing Crypto keys, attacker can easily
manipulate a specific segment of the network
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26. 26
Threats Against Secrecy
Unauthorized Data aggregation:
Eavesdropping and Passive Monitoring:
Traffic Analysis:
Possible if communication is not protected by
cryptographic mechanisms
Example: Location information gathering
identify some sensor nodes with special roles and
activities in a WSN.
It usually precedes the eavesdropping.
2 Mechanism : Rate Monitoring and Time Correlation
Camouflage:
An adversary may compromise a sensor node in a WSN
and later on use it to masquerade a normal node
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27. 27
Defense Against Attacks on
Sensor Privacy
Defense against Node Replication:
Randomized multicast:
Location Info is multicast to random witnesses.
Birthday Paradox is used to detect replicated
In a network of n nodes, if each location produces √n
witnesses, then, the birthday paradox predicts at least
one collision with high probability.
Line-selected multicast:
It uses network topology to detect replicated
It is based on the rumor routing protocol
If a conflicting location claim ever crosses the line
segment of location claim route to random witness,
replication is detected.
Communication overhead reduces from O(n2) to O(n√n)
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28. 28
Defense Against Attacks on
Unauthorized Data Aggregation
Defense against Traffic Analysis:
It prevents both rate monitoring and time
correlation.
It includes four mechanisms:
Forwarding to multiple parents
Controlled Random Walk in multi hop path
selection to distribute packet traffic
Random fake paths are introduced
Random areas of high communication
activities are created to deceive the attacker
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29. 29
Defense Against Attacks on Sensor
Privacy
Anonymity mechanisms:
An anonymity mechanism depersonalizes the data
before it is released from the source.
privacy and disclosure trade-off in location-based
services.
Four proposed approaches:
decentralization of storage of sensitive data
establishment of secure channel for communication
changing the pattern of data traffic
exploiting mobility of the nodes
Policy-Based approaches
Information Flooding:
Four mechanisms are proposed as follows.
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30. 30
Information Flooding mechanisms
to protect privacy
Baseline flooding:
Probabilistic flooding:
only a subset of nodes in the entire network participates in data
forwarding
There is packet loss possibility.
Flooding with fake messages:
every node in the network forwards a message only once
(Broadcast to all neighbors)
More sources can be introduced that inject fake messages into
the network to prevent back tracing.
Phantom flooding:
Probabilistic flooding same concept but changing the shortest
path in each packet transmission.
First phase takes hops through random walk (unicast)
Second phase floods the message through baseline flooding
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31. 31
Other security Mechanisms…
Intrusion
Detection
Secure Data Aggregation and Clustering
Secure Routing
Cryptography and key management
Trust Management
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32. 32
Important WSN Security
Protocols
SPIN
:
SNEP(secure network encryption protocol)
Provides
data confidentiality, two-party data
authentication, and data freshness for peer
to peer communication.
uTELSA (timed efficient streaming loss-tolerant
authentication protocol)
provides authenticated broadcast
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