This paper aims to detect and eliminate the Colluding Injected Attacks (CIA) in Mobile Ad hoc NETworks (MANETs). In CIA, the adversary will inject nodes into the network, making sure they aren't perceived as malicious nodes. These nodes blend into the network acting as legitimate nodes and plot against an arbitrary node. They prevent packets from reaching that node and then move on to attack the next node. This way the entire network gets compromised and the network parameters like throughput, delay and packet delivery ratio get affected. The attack is implemented in MANETs and a proposed algorithm named as Mitigating Colluding Injected Attack (MCIA) is used to detect and eliminate the attack.