Classification of security breaches and their impact on the market value of firms

While studies in other industries suggest that firm type, firm size, and time are important factors that explain the cross-sectional variations in abnormal stock market returns, studies in the area of IS security are inconclusive. In this study, we examine whether the characteristics of the incident – Attacker type, attacker’s objective, results of the attack, attack tools and access type influence the abnormal stock market return. Our results indicate that not all attacks have the same effect on the market value of companies. The results also help us create taxonomy of attacks and identify the factors that the market views as detrimental to the organization. We found that certain attacker type, the result of the attack and objective of the attacker and the tools used for the attack have significant impact on the abnormal stock market returns while the type of access obtained have marginal effect on the market value of the firm.