A Trust Model with Tolerance against the Behavior of Malicious Users

Nowadays، in spite of the presence of defense mechanisms and verification methods، parts of the security vulnerabilities still remain in systems. Therefore، protecting systems against all malicious behaviors and security attacks is nearly impossible. If the required countermeasures are not employed against the impacts of malwares، they may lead to intrusion and the violation of system security policies. On the other hand، intrusion-tolerant systems are used to increase the security of systems and software. Considering the concept of trust among the entities can play an important role to increase the security in distributed environments such as Internet. However، like other security mechanisms، trust is vulnerable to malicious attacks. Therefore، devising methods against malicious behaviors are very important. In this paper، a trust­-based approach for tolerating software against intrusion with emphasis to the relativity of trust concept is presented. So that، the precision of trust values for users in the whole system is increased، such that these values are closed to real values. The goal of the proposed approach is to diminish the challenges of absolute trust in order to make systems resilient against malicious behaviors through detecting real and non-real ideas of users and balancing them. The simulation results show that the proposed approach does not allow intruders to increase trust values unfairly and it is resilient against malicious and destructive behaviors. Furthermore، the addition of relativity to trust concept and the detection of malicious users lead to the improvement of the recommended method، comparing to the existing methods.