Abstract: Of all cyber-attacks, 'fabrication' which is aimed at impacting one’s awareness is becoming the common means, so it is of great importance to explore ways so as to defend such attacks. An attack can success or not always rely on the entities’ belief of certain events. In this paper, two different ways of 'fabrication' attack are put forward, and three essential conditions for 'fabrication' attack are analyzed. Second, a cyberspace belief model in terms of the Dempster-Shafer framework based on situation awareness theory is built to study the evolution of the cyber entities’ belief under the 'fabrication' attack. In addition, an algorithm used to compound D-S belief values among entities in cyberspace is designed. At last, the combination and evolution of D-S belief are studied on the scale-free network and the small world network, three conclusions are proposed at last.

Key words: cyberspace, Dempster-Shafer evidence theory, complex networks, situation awareness