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Mobile Security

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Satellites provide a 3-D position. No information about positions of neighbour devices ... Ultrasound (US) Measure the ToF of the sound signal between two nodes ... – PowerPoint PPT presentation

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Title: Mobile Security


1
CS 260 Seminar on Network Topology
How Does Topology Affect Security in Wireless Ad
Hoc Networks?
Ioannis Broustis broustis_at_cs.ucr.edu
2
Motivation
  • Wireless networks are more vulnerable to
    malicious attacks than wireline networks
  • Lack of base station
  • Limited power supply
  • Dynamically changing topology
  • Demand for innovative security algorithms
  • A lot of work has been done with private/public
    keys and cryptography
  • Only a few studies address topology-related
    aspects of security

3
Problems
  • Dynamically changing topology ? hard to
    distinguish between legitimate and malicious
    actions
  • Attackers can cheat on their actual location
  • Intrusion detection must be performed in a
    distributed manner
  • No base stations exist

4
Contribution
  • In this work..
  • We show how can the topological aspects of the
    network affect its safety from attackers
  • We describe the four location estimation
    techniques
  • We explain why these methods are vulnerable to
    attacks
  • We present all current mechanisms that detect
    intrusions having to do with topological aspects
  • We propose a new topology-related scheme that
    addresses most of the attacks

5
Attacks
  • Wormhole / tunnelling
  • Two attackers create a tunnel that can be
    secretly used to transmit packets.
  • Fake location claim
  • A node advertizes an erroneous location to its
    neighbours

6
Attacks
7
Relation to Topology
  • Fake location claims
  • Mobility allows a modification of the routing
    table of the victim node
  • Mobility of legitimate nodes may help attackers
    disperse their malicious information
  • Mobile nodes have power and computation
    limitations

8
Location Estimation
  • GPS(Global Positioning System)
  • Satellites provide a 3-D position
  • No information about positions of neighbour
    devices
  • Nodes must exchange their GPS information
    (dangerous)
  • Was not designed for security purposes
  • Attack Attacker feeds the GPS receiver with fake
    GPS messages

9
Location Estimation
  • Radio (RF)
  • Measure either the received RF signal strength,
    or the signal's ToF
  • Receiver calculates the distance from the RF
    sender by measuring the signal strength.
  • The receiver must trust the sender for the power
    at which the latter sent the RF signal.
  • - RF signals travel at the speed of light ?
    attackers cannot decrease the ToF of the signal ?
    ToF better

10
Location Estimation
  • Ultrasound (US)
  • Measure the ToF of the sound signal between two
    nodes
  • Often used together with the RF
  • Both the US and RF signals are transmitted at the
    same time.
  • Cannot be used outdoors
  • Animal unfriendly
  • Attacker may use the RF link to send the US

11
Location Estimation
  • Infrared (IR)
  • Measure ToF of the IR signal
  • Disadvantage a direct line-of-sight between the
    nodes is necessary
  • New links can be established by redirecting the
    existing light beams
  • Attacker cannot speed-up the signal from one node
    to the other upper-bound distances

12
Previous studies
  • They are divided into 3 main categories
  • Private/public key authentication and management
    (beyond the scope of our study)
  • Secure position-related ad hoc routing
    (interesting but we don't have time to talk about
    it now)
  • Secure location verification of a node's claim

13
N. Sastry, U. Shankar and D. Wagner, "Secure
Verification of Location Claims", EECS,
University of California, Berkeley.
  • A set of verifiers V wish to verify whether a
    prover p is in a region R of interest
  • Use of RF and US techniques
  • Time to reach p using RF the time for the
    return of the packet using US
  • If elapsed time gt threshold, V will reject the
    claim

14
N. Sastry, U. Shankar and D. Wagner, "Secure
Verification of Location Claims", EECS,
University of California, Berkeley.
  • Receiver's processing delay must be considered
  • Attack submit a position claim at the border of
    R
  • At the same time, advertise an erroneous value
    for processing delay
  • V thinks that p is inside R when in fact it is
    not
  • Solution V shrinks the allowable area
  • V should reject the claim when the claimed
    position is within Dp s of the outside border

15
N. Sastry, U. Shankar and D. Wagner, "Secure
Verification of Location Claims", EECS,
University of California, Berkeley.
  • Region of acceptance (ROA)

16
N. Sastry, U. Shankar and D. Wagner, "Secure
Verification of Location Claims", EECS,
University of California, Berkeley.
  • Region R is not always a circle
  • Use more verifiers to
  • cover the whole area
  • No key management or cryptography required.
  • No synchronization between V and p is required.
  • Problem is advertised Dp the actual one?

17
S. Capkun et. al, "Location Verification And Key
Management In Wireless Networks", MSc thesis,
EPFL 2004
  • 1. Use of Verifiable Multilateration
  • It is performed by a set of verifiers

18
S. Capkun et. al, "Location Verification And Key
Management In Wireless Networks", MSc thesis,
EPFL 2004
  • 2. Use of Verifiable Time Difference of Arrival
  • A set of verifiers is also used

19
S. Capkun et. al, "Location Verification And Key
Management In Wireless Networks", MSc thesis,
EPFL 2004
  • Use of Landmarks

20
S. Capkun et. al, "Location Verification And Key
Management In Wireless Networks", MSc thesis,
EPFL 2004
  • Secure distributed positioning
  • Basic Distance Verification (BDV)

21
Possible new scheme
22
Conclusion
  • The security aspects of the wireless network are
    closely related to its topology
  • Currently there is no optimal solution on many
    intrusion problems
  • New intelligent attacks are invented all the time
  • Difficult to design a general solution
  • Hot research subject

Slide theme Tom Karygiannis
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