Characterising File Sharing and its Protection, the Insider

File sharing has become an indispensable part of our daily lives. Some of the shared files are sensitive, thus, their confidentially, integrity and availability should be protected. This paper investigates the protection re-quirements and the activities of file sharing from the perspective of the insider threat problem. It addresses three fundamental questions to the design of a protec-tion mechanism against insider misuses: who is the insider, what are the insider misuses, and how the ac-tivity of file sharing can be performed. This paper proposes a new approach for classifying the insider threat problem into different categories and then fo-cuses on one category that is related to file sharing. It characterises the protection required by the shared files against different types of insiders misuses and charac-terises the activity file sharing based on two factors: how files can be propagated and how they can be ac-cessed after their propagation