The survey and classification of the different secu rity attacks in structured peer-to-peer (P2P) overlay ne tworks can be useful to computer system designers, programmers, administrators, and users. In this paper, we attempt to provide a t axonomy of structured P2P overlay networks security attacks. W e have specially focused on the way these attacks can arise at each level of the network. Moreover, we observed that most of the exi sting systems such as Content Addressable Network (CAN), Chord, Pastry, Tapestry, Kademlia, and Viceroy suffer from threats and vulnerability which lead to disrupt and corrupt their functioning . We hope that our survey constitutes a good help for who's working on this area of research. Keywords—P2P, Structured P2P Overlay Networks, DHT, Security, classification I. INTRODUCTION 2P networks systems have generated substantial inte rest in the last few years because the emergent of global s cale phenomena. As more and more users own powerful processors, large storage spaces and fast network c onnections, P2P networks represent an attractive way to mobiliz e these resources. They were designed to provide many services such as creating large scale data sharing, distributed c omputing, instant messages communication, collaborative appli cations, multi players games, and ad-hoc network. These popular services make P2P networks an attractive target for attackers. Knowing how systems have failed can help us build systems that resist failure (1). This paper collects and or ganizes a number of current security attacks that have caused failure in structured P2P overlay networks, so computer system designer, programmers, administrators, and users ma y do their work with a precise knowledge of what has gone before. Based on the overlay topology and the organization of the network connection different types of P2P networks have been defined as hierarchical P2P network, and flat P2P n etwork. In this paper, we will focus on hierarchical P2P netwo rk, more precisely on structured P2P overlay networks. Security attacks of structured P2P overlay network are any condition or circumstance that can threaten the bes t functioning of the system. To evaluate these attacks, an analyst must do a dee ply research, understand the system fluently, and recog nize that attacks may exist anywhere in the system.