The Feasibility of Launching
and Detecting Jamming
Attacks in Wireless Networks
Authors: Wenyuan XU, Wade Trappe, Yanyong Zhang and Timothy Wood
Wireless Information Network Laboratory, Rutgers University
Presented by Zigeng Wang and Shaobo Zheng
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What is Jamming?
Useful Information
Alice
Bob
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What is Jamming?
Useful Information
Alice
Bob
Eve (Jammer)
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What is Jamming?
• Jamming is the (usually deliberate)
transmission of radio signals that disrupt
communications by decreasing the signal-tonoise ratio.
• Radio interference attack
• In network scenario, how to measure the
effectiveness of a Jammer?
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Jamming Performance Metrics
• Packet Send Ratio (PSR)
The ratio of packets that are successfully sent out by a
legitimate traffic source compared to the number of
packets it intends to send out at the MAC layer.
• Packet Delivery Ratio (PSR)
The ratio of packets that are successfully delivered to a
destination compared to the number of packets that have
been sent out by the sender.
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Jamming Attack Models
• Constant Jammer
• Continually emitting random signals
• Deceptive Jammer
• Constantly injecting regular packets
• Random Jammer
• Switching between sleeping and Jamming
• Reactive Jammer
• Start transmission when senses activity on the channel
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Jamming Attack Models
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Jamming Attack Detection
• Signal Strength
• discrimination
- Detect jamming by extracting spectral characteristics of
the signal strength for the basis of discrimination by
implying higher order crossings (HOC)
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Jamming Attack Detection
• Signal Strength
• Signal Strength Spectral Discrimination
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Jamming Attack Detection
• Signal Strength
• Signal Strength Spectral Discrimination
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Jamming Attack Detection
• Carrier Sensing Time
• Thresholding mechanism: Each time A wishes
to transmit, it will monitor the time spent
sensing the channel, and if that time is above a
threshold (or if it is consistently above the
threshold), it will declare that a jamming is
occurring.
• Theoretically calculating is hard
• Statistics approach
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Jamming Attack Detection
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Jamming Attack Detection
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Jamming Attack Detection
• Packet Delivery Ratio
• Any one of the four jammers, if placed within a
reasonable distance from the receiver, can
cause the corresponding PDR to become close
to 0.
• Even under such a congestion level, the PDR
measured by the receiver is still around 78%.
• It is not as effective for other network
dynamics, such as a sender battery failure, or
the sender moving out of the receiver's
communication range.
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Basic Detection Summary
• Both Signal Strength and Carrier Sensing time can
only detect the constant and deceptive jammer.
Neither of these two statistics is effective in
detecting the random or the reactive jammer.
• Packet Delivery Ratio is a powerful statistic to
determine Jamming vs. congestion. It can not
account for all network dynamics.
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We need Consistency Checks to
be Sure
1.
2.
Signal Strength Consistency Checks
Location Consistency Checks
Assumptions
•
Each node detects whether it is jammed
•
Each node maintains a neighbor list from routing layer
•
Network deployment is dense so each node has several neighbors
•
All legitimate nodes participate by sending heartbeat beacons(
allows for reliable estimate of PDR over time)
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Advanced Jamming Detection
• Signal Strength Consistency Checks
• In order to combat false detections due to legitimate
causes of link degradation, we use the signal strength as
a consistency check. Specifically, we check to see
whether a low PDR value is consistent with the signal
strength that is measured.
• it may not be practical to sample the signal strength with
a fine granularity over a long window of time
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4.1 Signal Strength Consistency Checks
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4.1 Signal Strength Consistency Checks
PDR VS. SS
Observed Normal relationships
•High signal strength yields a high PDR
•Low signal strength yields a low PDR
Jammed Region
•The Jammed region has above 99%
signal strength confidence intervals and
whose PDR is below 65%
SS(dBm)
•Jammed scenario: a high signal
strength but a low PDR
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PDR %
Advanced Jamming Detection
• Location Consistency Checks
• a proactive consistency check.
• all legitimate neighbor nodes transmit with a
fixed power level
• requires the support of a localization
infrastructure
• every node periodically advertise its current
location and further let each node keep track
of both the PDR and the location of its
neighbors.
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Advanced Jamming Detection
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PDR VS Distance
Observations:
•Neighbors that are close should have
high PDR values, if they have low PDR
values they are Jammed
•All nodes advertise their current
location and their PDRs to their
neighbors to ensure there is a minimum
amount of traffic to establish PDR. Thus
PDR = 0 if no packets received
•Similar to the SS consistency check. An
initial baseline to represent the profile
of a normal environment (PDR,d) for
each node.
•If a lower PDR is observed than should
be for a given distance under normal
radio conditions than the node declares
it is Jammed.
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• Countermeasures : Physical layer design
technologies such as spread spectrum work but
have not found wide spread deployment in
commodity wireless devices.
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Conclusions
• Protecting our wireless networks is important
• Jamming is a viable threat
• Detecting Jamming is the first step in defeating it
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