Using Directional Antennas to Prevent Wormhole Attacks

1
Using Directional Antennas to Prevent Wormhole
Attacks

• Presented by Juan Du
• Nov 16, 2005

2
Outline

• Wormhole attacks
• Related works
• Three neighbor discovery protocols
• Directional Neighbor Discovery
• Verified Neighbor Discovery
• Strict Neighbor Discovery
• Conclusion and future work

3
Wormhole Attacks

• A, B, C nodes in wireless networks
• X, Y transceivers connected by a high quality,
  low-latency link
• Attacker replays packets received by X at Y,
  and vice versa
• Makes A and B believe they are neighbors
• Selectively drop data messages to disrupt
  communications

4
Wormhole Impact

• Cost
• Limited resources needed
• No cryptographic material needed
• Damage to routing
• Impact beyond the endpoints neighborhoods!
• Endpoints placed strategically
• Worst case disrupts nearly all network routes

5
Related Works

• Secure routing protocols such as SRP, SEAD,
  Ariadne, ARRIVE,
• Still vulnerable to wormhole attacks
• Location based routing protocols
• Have the potential
• Have drawbacks
• Localization systems become attack target
• Need synchronized clocks and precise location
  knowledge

6
Protocol Idea

• Wormhole attack depends on a node that is not
  nearby convincing another node it is
• Solution
• Verify neighbors are really neighbors
• Only accept messages from verified neighbors

7
The Technique Directional Antennas

• Divide transmission range into N zones clockwise
  starting with zone 1 facing east.
• All nodes have the same orientation.
• A node can get approximate direction information
  based on received signals

8
Notations

• A, B, C... Legitimate nodes
• X, Y Wormhole
  endpoints
• R Nonce
• EKAB(M) Message encrypted by
  key shared between
• nodes A
  and B
• zone The directional
  element, which ranges
• from
  16 as shown in figure
• zone The opposite
  directional element. For
• 
  example, if zone1 then zone4.
• zone (A, B) Zone in which node A
  hears node B
• neighbors (A, zone) Nodes within one
  (directional distance)
• hop in
  direction zone of node A.

9
Directional Neighbor Discovery
1. A ? Region HELLO IDA Sent in every
direction 2. N ? A IDN EKNA (IDA R zone
(N, A)) Sent in zone (N, A) 3. A ?
N R Checks zone is opposite, sent in zone (A,
N)
10
Directional Neighbor Discovery (Cont.)

• The protocol itself is vulnerable to wormhole
  attacks
• Attacks effectiveness is reduced
• Only node pairs that are in opposite directions
  relative to the wormhole in each region will
  accept each other as neighbors (e.g. A and C)
• How about A and B?

11
Verified Neighbor Discovery

• Observation Cooperate!
• Wormhole can only trick nodes in particular
  locations
• Verify neighbors using other nodes
• Need receive confirmation from a verifier node
  before accepting a new neighbor
• Need prevent verifiers from acting through the
  wormhole
• A valid verifier V for the link A B must
  satisfy
• zone (B, A) ? zone (B, V)
• B hears V in a different zone from node A
• zone (B, A) ? zone (V, A)
• B and V hear node A from different directions

12
Verified Neighbor Discovery (Cont.)

• 1. A ? Region HELLO IDA
• 2. N ? A IDN EKNA (IDA R zone (N,
  A))
• 3. A ? N R

Same as before

• 4. N ? Region INQUIRY IDN IDA zone
  (N, A)
• Sent in directions except
  zone (N, A) and zone (N, A)
• 5. V ? N IDV EKNV (IDA zone (V, N))
• V satisfies
  verifier properties and completed 1-3
• 6. N ? A IDN EKAN (IDA ACCEPT)
• N must receive at
  least one verifier response

13
Effect of Verified Neighbor Discovery

• D as the verifier
• zone (D, A) 3 zone (A, D) 1
• wormhole cannot convince D and A to accept each
  other as neighbors
• B will not be able to verify A as a neighbor
  through D

• Secure against wormhole attacks that involve two
  distant endpoints

14
Strict Neighbor Discovery

• Worawannotai attack
• B and A are unable to communicate directly, but
  close enough to have a verifier that can hear
  both A and B

15
Analysis

• Advantage
• Low overhead
• Directional antennas
• Energy conservative
• Better spatial reuse of bandwidth
• Disadvantage
• May prevent legitimate links from being
  established because of no potential verifier node
• For network density of 10 neighbors, less than
  0.5 (or 40) of links are lost and no (or 0.03)
  nodes are disconnected in verified (or strict)
  neighbor discovery protocol

16
Conclusion and Future Work

• Conclusion
• Wormhole attacks are a powerful attack which
  depend on a node misrepresenting its location
• Directional antennas offer a promising approach
• Future work
• Multiple wormhole endpoint attacks
• Robustness

17
Questions?

• Thank you!