Abstract—In Mobile Ad hoc Network (MANET), performance of the routing protocols is degraded by various network attacks such as black hole attack and rushing attack. Mostly all layers of mobile ad hoc networks are vulnerable to several attacks. Routing protocols used in mobile ad hoc networks are designed by considering that all the nodes are trustable in communication mode. MANET is less secure network due to its features like no centralized administration control and no infrastructure is required. In this paper, Ad hoc On Demand distance Vector (AODV) routing protocol is evaluated under rushing attack, black hole attack, and grayhole attack. Under multiple attacking, single attacking, and without attacking modes, performance of network has been evaluated. By varying the speed, network size, node density, and number of attacking nodes, four different network scenarios have been generated. Performance metrics are considered as average throughput, average end to end delay and packet delivery ratio. Network simulator 2 is used to simulate the attacks over AODV routing protocol. Results show that all the above attacks are responsible for the poor throughput, heavy dropping packets and higher end to end delays in the network. Throughput is degraded as the numbers of attacking nodes are increased. AODV is less affected by rushing attack as compared to black hole and grayhole attacks.