Layer wise attacks Physical and link layer attacks in WSN Attacks
WSNs are vulnerable to various types of attacks. These attacks can be broadly categorized as follows :
Attacks on network availability attacks
Attacks on secrecy and authentication
Stealthy attack against service integrity
The physical layer is responsible for frequency selection, carrier frequency generation, signal detection, modulation, and data encryption.
As with any radio-based medium there exists the possibility of jamming in WSNs.
(i) Jamming
It is a type of attack which interferes with the radio frequencies that the nodes use in a WSN for communication.
A jamming source may be powerful enough to disrupt the entire network.
Even with less powerful jamming sources, an adversary can potentially disrupt communication in the entire network by strategically distributing the jamming sources.
(ii) Tampering
Sensor networks typically operate in outdoor environments.
Due to unattended and distributed nature, the nodes in a WSN are highly susceptible to physical attacks.
The physical attacks may cause irreversible damage to the nodes
Jamming and tampering attacks can be prevented by using methods like
spread lower duty cycle,
spectrum,
priority messages,
region mapping,
Tamper proofing,
mode change and node hiding.
The link layer is responsible for multiplexing of data-streams, data frame detection, medium access control, and error control.
Attacks at this layer include purposefully created collisions, resource exhaustion, and unfairness in allocation.
A collision occurs when two nodes attempt to transmit on the same frequency simultaneously.
When packets collide, they are discarded and need to be retransmitted.
An adversary may strategically cause collisions in specific packets such as ACK control messages.
The adversary may simply violate the communication protocol and continuously transmit messages in an attempt to generate collisions.
Repeated collisions can also be used by an attacker to cause resource
exhaustion.
Link layer attacks can be prevented by using
error detection code,
rate limitation and
by dividing the packets into small frames.