Abstract: Ad-hoc networks are smart protocol that service the technology and is used in many applications such as rescue and strategic operations, due to the suppleness provided by their active structure. However, this suppleness is attended with new security threats. Moreover, many developed security solutions used for wired networks are unsuccessful and unproductive for the highly dynamic and use wide of resources where MANET resources are limited expected. In this study a proposed of Cross Layer Based Defense Enhancement Technique "CBDET" to solve this problem.