On Estimating the Security Risks of Composite Software Services

With the rapid adoption of the Service Oriented Architecture (SOA), sophisticated software systems are increasingly built by composing coarse-grained service components offered by different organizations through standard web service interfaces. The ability to quantify end-to-end security risks of composite software services is extremely valuable to businesses that increasingly rely on web applications to interact with their customers and partners. In this position paper, we propose a framework that predicts the probability of end-to-end security breaches of a software service by using a combination of three models: (1) a software security model that describes the probability distribution of security bugs in individual components, (2) a service composition model that describes the interactions of components and the contribution of security bugs in individual components to the overall security of the service, and (3) a hacking exposure model that estimates hackers’ knowledge of individual components and hence the probability that a security hole, if exists, may be exploited.