Abstract: “Mobile Ad Hoc Network (MANET) is a collection of communication devices or nodes that wish to communicate without any fixed infrastructure and pre-determined organization of available links. Security is a major challenge for these networks owing to their features of open medium, dynamically changing topologies. The black hole attack is a well known security threat in MANET. However, it spuriously replies for any route request without having any active route to the specified destination. Sometimes the black hole nodes cooperate with each other with the aim of dropping packets. These are known as cooperative black hole attack. In this paper, we have reviewed different techniques for detection against Cooperative Black hole attacks in Mobile Ad-Hoc networks and thoroughly compare these schemes to find out their various advantages and disadvantages”

Keywords: AODV, Black hole attack, MANET, routing protocols, Security