Abstract: The threat of botnet on network security has been attached great importance by many security search ex- pens. Mathematical modeling is a kind of effective method to study botnet propagation. Existing botnet propagation models assume that infection rate is constant. However in fact, network congestion will be caused when a large number of botnet viruses rampant. Against this backdrop, a botnet propagation model with variable infection rate was proposed, which considers pre-immunity according to the real situation of Internet. Finally, the difference of botnet infection be- tween the model of this paper and existing models was depicted in matlab. Experimental results show that the botnet propagation model with variable infection rate is more accurate to reflect the practical propagation law of hots.

Key words: Botnet, Propagation model, Network security, Computer virus