Attack on the Basis of Routing

There are lots of routing protocols proposed for transmitting the data in the network from source to sink. In this transmission process, an attacker can modify the information with the help of different attacks. Some of the routing attacks are explained below:

a) Wormhole Attacks:

In this attack there are two or more malicious nodes present in the network at different locations. When sender node sends an information then one malicious node tunnels the information to another malicious node. The receiving malicious node then sends information to its neighbor nodes. In this way, attacker convince the sender and receiver nodes that they are situated at a distance of one or two hops but actual distance between these two are multiple hops and usually both are out of range.

Mostly wormhole attack and selective forwarding both are used in combination. If it is used in combination with Sybil attack then detection of attack is difficult.

Figure shows that the node X and node Y are nodes which are maintaining the wormhole link in the network and they are the two malicious nodes. There is a shortcut link between both malicious nodes known as wormhole link. Node A sends message which is received by node X. Node X sends message to Node Y through wormhole link which further sends it to its neighbor node B.

                                      Wormhole Attack

b) HELLO Flood Attacks:

In a sensor network to discover the neighbors HELLO message is broadcasted by the nodes. The receiver node considers that the source node is in the range of data tranmission and sends its sensed data to the broadcaster. In a HELLO Flood Attack, HELLO message is broadcast with high transmission power by the attacker. The nodes which receive this HELLO message send the data packets to the attacker node. Attacker may change or modify the data packet or may drop the packet.

In this way, a lot of energy is wasted and also network congestion occurs. This attack is one of the least difficult attacks in WSN. As demonstrated in Figure-1 attacker node broadcasts the HELLO packet with high transmission power than the sink. Figure-2 shows that the nodes which receive HELLO packet from attacker node consider it as a neighbor node and send/reply the sensed data packet to the attacker node.

c) Selective Forwarding Attack:

In this attack, a malicious node in the network interrupts the communication process. There may be the case of multiple malicious nodes in the network that depends upon the attacker.

This node selectively forwards some of the received packets. This malicious node can also be referred as a black hole as it may drop all the received packets. In such case, neighboring nodes assumes that this has failed and starts searching for another route. This attack is easy to detect if it acts as a black hole and drop all the received packets but is complicated if it forwards packet selectively. On the premise of packets drops, it is divided into two categories:

1: Drops packets of some specified nodes

1: Drops packets of some specified types

Figure  shows a malicious node present between the nodes in network. In this neighboring node unknowingly forwards packets to the malicious node.

d) Sybil Attack:
In Sybil Attack, a single attacker makes and presents different identities to the other nodes in the sensor network. It can also be considered that “It can be in more than one place at once”. Malicious nodes are known as Sybil nodes. This attack is used against redundancy mechanism of distributed systems. In WSNs, Sybil attack is generally used to attack several types of protocols. This is a serious threat to a location based  protocols in which location information is exchanged for efficient routing.

e) Sinkhole Attack:
In sinkhole attack, a malicious node advertises fake routing information to attract the network traffic. WSNs are vulnerable to this type of attack because communication happens in many to one form i.e. many sensor nodes to a single BS. Wormhole attack can also be used in combination with this attack. In Figure, malicious node has more power than other nodes in the network and connects with the sink node using single hop. It claims and displays to have the shortest possible path to the sink so that more network traffic is
attracted towards it. Most of the routing algorithms select the
shortest path for data transfer.

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