Building in web application security at the requirements stage : a tool for visualizing and evaluating security trade-offs : a thesis presented in partial fulfilment of the requirements for the degree of Master of Information Science in Information Systems at Massey University, Albany, New Zealand

Abstract

One dimension of Internet security is web application security. The purpose of this Design-science study was to design, build and evaluate a computer-based tool to support security vulnerability and risk assessment in the early stages of web application design. The tool facilitates risk assessment by managers and helps developers to model security requirements using an interactive tree diagram. The tool calculates residual risk for each component of a web application and for the application overall so developers are provided with better information for making decisions about which countermeasures to implement given limited resources tor doing so. The tool supports taking a proactive approach to building in web application security at the requirements stage as opposed to the more common reactive approach of putting countermeasures in place after an attack and loss have been incurred. The primary contribution of the proposed tool is its ability to make known security-related information (e.g. known vulnerabilities, attacks and countermeasures) more accessible to developers who are not security experts and to translate lack of security measures into an understandable measure of relative residual risk. The latter is useful for managers who need to prioritize security spending. Keywords: web application security, security requirements modelling, attack trees, threat trees, risk assessment.