During the past two decades, mobile internet technologies have been dramatically growing while leading to a paradigm shift in our life. Despites their revolution, mobile internet technologies open doors to various security threats, which should be addressed to keep mobile Internet environments to be secure and trust. Even worse, the latest technologies (e.g. distributed mobility management, mobile internet of things, 5G networks, and so forth) continuously have introduced new security challenges. Therefore, it is of paramount importance to study mobile internet security. The purpose of MobeSec 2017 is to bring together the academic and industry working on different aspects, exchange ideas, and explore new research directions for addressing the challenges in mobility internet security. MobeSec 2017 also aims to publish high quality papers, which are closely related to various theories and practical applications in mobility management to highlight the state-of-art research. In spite of focusing on security aspects, this symposium welcomes papers which are related to mobile internet technologies. We expect that MobeSec 2017 will be a trigger for further research and technology improvements related to this important subject.