Stability Analysis of A Delayed Model of the Spread of Worms

There has been a constant barrage of worms over the internet during the recent past. To develop appropriate tools for thwarting quick spread of worms, researchers are trying to understand the behavior of the worm propagation with the aid of epidemiological models. In this study, we apply a modification of SIR model to study worm propagation. Whereas in the SIR model once a node is cured after infection it becomes permanently immune, we assume this immunity to be temporary, since the cured nodes may again become infected, maybe with a different strain of the same worm. So we obtain a differential system with time-delay. Global stability of equilibriums of the model is studied in this paper.