D2D allows a powerful communication among devices where it allows devices to act as relay or devices both working intelligently. It is one of the promising technology of 5G that provides high coverage and maximum capacity as well as increased number of devices. It provides the devices to act as small eNB or Base station to form a small network in an infrastructural or non-infrastructural mode. These intelligent device poses an inherit threats or security. This paper highlights major security attacks that can be done of D2D such as Denial of Service attacks in from of black hole, grey hole, Sybil or injection attacks. Second form can be Man in the middle attack as well as side channel attacks.