Comparing Decision Support Approaches for Cyber Security Investment

TL;DR

This paper compares game theory, combinatorial optimization, and hybrid approaches for cyber security investment decision support, highlighting their strengths, weaknesses, and the impact of costs through a case study.

Contribution

It introduces a framework for evaluating decision-support methods for cyber security investments and compares their effectiveness using a case study based on critical controls.

Findings

Game theory and combinatorial optimization have distinct strengths and weaknesses.

Hybrid approach benefits from combining game solutions with cost optimization.

Indirect costs significantly influence optimal cyber security investment strategies.

Abstract

When investing in cyber security resources, information security managers have to follow effective decision-making strategies. We refer to this as the cyber security investment challenge. In this paper, we consider three possible decision-support methodologies for security managers to tackle this challenge. We consider methods based on game theory, combinatorial optimisation and a hybrid of the two. Our modelling starts by building a framework where we can investigate the effectiveness of a cyber security control regarding the protection of different assets seen as targets in presence of commodity threats. In terms of game theory we consider a 2-person control game between the security manager who has to choose among different implementation levels of a cyber security control, and a commodity attacker who chooses among different targets to attack. The pure game theoretical methodology consists of a large game including all controls and all threats. In the hybrid methodology the game solutions of individual control-games along with their direct costs (e.g. financial) are combined with a knapsack algorithm to derive an optimal investment strategy. The combinatorial optimisation technique consists of a multi-objective multiple choice knapsack based strategy. We compare these approaches on a case study that was built on SANS top critical controls. The main achievements of this work is to highlight the weaknesses and strengths of different investment methodologies for cyber security, the benefit of their interaction, and the impact that indirect costs have on cyber security investment.