policy-driven physical attacks in sensor networks: modeling and measurement

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T H E O H I O S T A T E U N I V E R S I T Y

Computer Science and EngineeringComputer Science and EngineeringT H E O H I O S T A T E U N I V E R S I T Y

Computer Science and EngineeringComputer Science and Engineering

Xun Wang†, Sriram Chellappan†, Wenjun Gu†,

Wei Yu‡ and Dong Xuan†

Presented by Wei Yu

†Department of Computer Science and EngineeringThe Ohio State University

‡ Department of Computer ScienceTexas A & M University

Xun Wang†, Sriram Chellappan†, Wenjun Gu†,

Wei Yu‡ and Dong Xuan†

Presented by Wei Yu

†Department of Computer Science and EngineeringThe Ohio State University

‡ Department of Computer ScienceTexas A & M University

Policy-driven Physical Attacks in Sensor Networks:Modeling and Measurement

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Physical Attacks are Salient Threats to Sensor Networks

• Sensor network applications that operate in hostile environments– Volcanic monitoring– Battlefield applications– Anti sensor network forces

• Physical attacks are inevitable in sensor networks– Physical attacks: destroy sensors physically – Simple to launch

• Small form factor of sensors• Unattended and distributed nature of deployment

– Can be fatal to sensor networks– Different from other types of electronic attacks

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Outline

• Physical attacks in sensor networks

• Modeling Policy-driven physical attacks

• Measurement of Policy-driven physical attacks

• Countermeasures to physical attacks

• Final remarks

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Physical Attacks – A General Description

• Physical attacks are those that result in the physical destruction of sensors

• Two broad types of sensor destruction methods – Bombing:

• Brute-force physical destruction with bombs/ grenades; Sensors in the attack area are destroyed.

• Fast; Not accurate due to blind destruction. – Sweeping:

• Detecting sensors by detecting signals emitted by sensors then isolating an area for the detected sensor; Reaching the isolation area; Destroying small size sensors through physical destruction methods.

• Slow; Accurate destruction of only isolated area.

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Attacker Objectives and Dilemma

• Two objectives of the attacker – Destroy sensor network.

– Preserve the sensor network deployment field.

– Attacker might have certain bias between them.

– How the attacker can achieve its objectives with certain bias?

• Choose Bombing or Sweeping?– Bombing is good at rapidly destroy sensor network, but causes too large

causalities to deployment field.

– Sweeping is good at preserve sensor network deployment field, but it is slow in destroying sensors.

• A policy-controlled combination of Bombing and Sweeping to achieve the desired bias between the two objectives– Policy-driven physical attacks

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Policy-driven Physical Attacks• Targeting phase

– Search for sensors by detecting signals emitted by sensors and isolating an area (isolation-area) for each detected sensor.

• Destruction phase– Choose destruction method (bombing or sweeping) according to

policy and information of the detected sensor.– If choose bombing

• Use brute-force physical destruction with bombs/ grenades or tanks/ vehicles on the isolation area of the detected sensor.

– If choose sweeping • Reach the isolation area of the detected sensor• Destroying small size sensor through physical destruction

methods (like physical force, radiation, hardware/ circuit tampering).

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Modeling of Policy-driven Physical Attacks

• Sensor network signals– Passive signal and active signal

• Attacker capacity– Signal detection and sensor Isolation– Sensor destruction methods

• Attack Model– Attack model procedure– Attacker’s bias between two objectives– Attack action control

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Network Parameters and Attacker Capacities

• f: Active signal frequency

• Rps: The maximum distance can detect a passive signal • Ras

s: The maximum distance can detect an active signal emitted by a normal sensor

• θ: Isolation accuracy

–ri =di θ

–Isolation/sweeping area: Dswi=πri

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• Vmv: Attacker moving speed

• Vsw: Attacker sweeping speed

•μ: bombing rate

• Rb: Radius of destruction area of

each bombing

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Policy-driven Physical Attack procedure

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Metrics and Quantification of Policy• AC: Accumulative Coverage

– EL: Effectively Lifetime is the time period until when the sensor network becomes nonfunctional because the coverage falls below a certain threshold α

– Coverage(t): Instant network coverage at time t

• DC: Destruction CasualtyIf the attacker attacked a set of n sensors K = {S1, ..., Sn}, and the

destroyed area for sensor Si is Di, then

• P : In Policy-driven Physical Attacks, the policy (P) represents the bias among the twin objectives of the attacker.

0( )

EL

tAC coverage t dt

i

iS K

DC D

i

iS K

DC D

i

iS K

DC D

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Impact of Destruction Methods on DC, ACand Attack Action Control

• Impact of Sweeping and Bombing on DC (Destruction area)

Dswi=πri

2 , Dboi=π(ri+Rbe)2

Rbe is is the bombing area error margin which represents the extra casualty (extra destruction area) caused by the less-accurate bombing.

• Impact of Sweeping and Bombing on AC (Time cost)

Tswi = tsw

i + tmvi = πri

2/vsw + d’i/vmv

Tboi = tbo

i = Dboi/ π Rb

2/ μ = π(ri+Rbe)2 / π Rb2/ μ

• Selection between Sweeping and Bombing

Fbo(i) = Tboi * (Dbo

i)P Fbo(i) = Tswi * (Dsw

i)P

- Choose Bombing if Fbo(i) ≤ Fsw(i)

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Sensitivity of AC, DC to P with Different μand Rb

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Sensitivity of AC, DC to P with Different vsw and θ

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Countermeasures to Physical Attacks

• For Blind Physical Attacks– Overly and optimally deploying sensors to prolong lifetime of

sensor networks under blind physical attacks

• For Search-based Physical Attacks– Deterring the search process (at the target phase)

┼ Physically protecting sensors

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Final Remarks

• Physical attacks are patent and potent threats to sensor networks.

• Policy-driven physical attacks can achieve desired bias between the twin objectives of the attacker (rapidly destroying sensors, and preserving the deployment field).

• Viability of future sensor networks is contingent on their ability to resist physical attacks.

• Our research is an important first step in this regard.

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Q&A

Thank You !

policy-driven physical attacks in sensor networks: modeling and measurement

Documents

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sensor networksmodeling

bombs grenades sensors

sriram chellappan

wenjun gu

dong xuanpresented

salient threats