In this paper, a nonlinear mathematical model has been proposed and analyzed to study the role of antivirus program to clean an infected computer network. The model has been proposed by employing the concept of epidemics, where nodes in the network are considered as populations. The total numbers of nodes have been divided into susceptible nodes, infected nodes, and protected nodes. The variable representing the number of antivirus programs considered in the model has been assumed to be proportional to the number of infected nodes. The model has been analyzed using stability theory of differential equations and numerical simulation. The model has only one equilibrium namely the endemic equilibrium. This endemic equilibrium is found to be locally as well as nonlinearly stable under certain conditions. This implies that under some conditions, the entire network can be cleaned if a class of the protected nodes is formed in the system. The protected class accelerates the process of cleanness as isolation being done by another antivirus software protecting these nodes.