In this paper proposed an innovative approach for the detection of the dangerous gray hole attack as well as black hole attack. AODV is an important on-demand distance vector routing protocol for mobile ad hoc networks. It is more vulnerable to black hole and gray hole attack. A Gray hole is a node that selectively drops and forwards data packets after advertises itself as having the shortest path to the destination node in response to a route request message. In a black hole attack, a malicious node sends false routing information, claiming that it has an optimum route and causes other good nodes to route data packets through the malicious one. Many researchers have given special solutions for preventing and detecting of these attacks.