Other e?±cient security mechanisms need to be designed to
defend against the collision attack.
Exhaustion
If a contention-based MAC protocol is used in the network, an adversary
may attempt transmission repeatedly, and this renders neighbor sensor nodes
unable to transmit any frame. For example, IEEE 802.11-based MAC protocols
[40] use Request-To-Send (RTS), Clear-To-Send (CTS), and Data/Ack
messages to reserve channel access and transmit data. An adversary could
repeatedly request channel access with RTS, eliciting a CTS response from
the targeted neighbor. If the adversary is a powerful node (e.g., a laptop with
long transmission range and rechargeable energy supply), the adversary could
block sensor transmissions in a large area and could exhaust the energy of
targeted sensor nodes. Possible solutions include limiting the MAC admission
control rate of each node, or using MAC protocols that combine time-slotted
mechanisms (like TDMA) and contention-based mechanisms.
2.3 Attacks on Routing
Many sensor network routing protocols are quite simple, and for this reason
are susceptible to several kinds of attacks. Attacks on sensor networks have
been discussed in several papers [3, 12, 13, 14]. Most network layer attacks
against sensor networks fall into one of the following categories: manipulating
routing information; selective forwarding; Sybil [16]; sinkhole; wormhole [15];
and Hello flooding (unidirectional) attacks [3].
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