Online Promiscuity: Prophylactic Patching and the Spread of Computer Transmitted Infections

There is a long history of studying the epidemiology of computer malware. Much of this work has focused on the behaviors of specific viruses, worms, or botnets. In contrast, we seek to utilize an extension of the simple SIS model to examine the efficacy of various aggregate patching and recovery behaviors. We use the SIS model because we are interested in the global prevalence of malware, rather than the dynamics, such as recovery, covered in previous work. We consider four populations: vigilant and non-vigilant with infected or not for both sets. Using our model we show that small increases in patch rates and recovery speed are the most effective approaches to reduce system-wide vulnerabilities due to unprotected computers. Our results illustrate that a public health approach may be feasible, requiring a subpopulation adopt prophylactic actions rather than near-universal immunization.