• Journal of Internet Computing and Services
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• v.15 no.3
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• pp.91-100
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• 2014

While IT security investment of organizations has been increased, the amount of the monetary loss of organizations caused by IT security breaches did not decrease as much as their expectation. Also, from surveys, it was discovered that the poor usage of their security budget thwarted the improvement of the organization's security level. In this paper, to resolve the poor usage of security budget of organizations, we propose a comprehensive economic model for determining the optimal amount of investment in security solutions, including the proactive security solutions(PSSs) and the reactive security solutions(RSSs). Using the proposed analytical model under different parameters of security solutions, we show the optimal condition to maximize the expected net benefits from IT security investment of organizations. Also, we verify the common belief that the optimal level of investment in security solutions is an increasing function of vulnerability. Through simulations, we find the optimal level of IT security investment, given parameters of different characteristics of security solutions.

• Journal of Information Technology Services
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• v.18 no.5
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• pp.155-164
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• 2019

With the emergence of new ICT technologies, information security threats are becoming more advanced, intelligent, and diverse. Even though the awareness of the importance of information security increases, the information security budget is not enough because of the lack of effectiveness measurement of the information security investment. Therefore, it is necessary to optimize the information security investment in each business environment to minimize the cost of operating the information security countermeasures and mitigate the damages occurred from the information security breaches. In this paper, using genetic algorithms we propose an investment optimization model for information security countermeasures with the limited budget. The optimal information security countermeasures were derived based on the actual information security investment status of SMEs. The optimal solution supports the decision on the appropriate investment level for each information security countermeasures.

• Asia pacific journal of information systems
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• v.21 no.4
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• pp.27-43
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• 2011

This article explores economic models that show the optimal level of information security investment in the presence of interdependent security risks, Using particular functional forms, the analysis shows that the relationship between the levels of security vulnerability and the levels of optimal security investments is affected by externalities caused by agents' correlated security risks. This article further illustrates that, compared to security investments in the situation of independent security risks, in order to maximize the expected benefits from security investments, an agent should invest a larger fraction of the expected loss from a security breach in the case of negative externalities, while an agent should spend a smaller fraction of the expected loss in the case of negative externalities.

• Journal of Intelligence and Information Systems
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• v.26 no.3
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• pp.37-50
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• 2020

Information security has become an important issue in the world. Various information and communication technologies, such as the Internet of Things, big data, cloud, and artificial intelligence, are developing, and the need for information security is increasing. Although the necessity of information security is expanding according to the development of information and communication technology, interest in information security investment is insufficient. In general, measuring the effect of information security investment is difficult, so appropriate investment is not being practice, and organizations are decreasing their information security investment. In addition, since the types and specification of information security measures are diverse, it is difficult to compare and evaluate the information security countermeasures objectively, and there is a lack of decision-making methods about information security investment. To develop the organization, policies and decisions related to information security are essential, and measuring the effect of information security investment is necessary. Therefore, this study proposes a method of constructing an investment portfolio for information security measures using game theory and derives an optimal defence probability. Using the two-person game model, the information security manager and the attacker are assumed to be the game players, and the information security countermeasures and information security threats are assumed as the strategy of the players, respectively. A zero-sum game that the sum of the players' payoffs is zero is assumed, and we derive a solution of a mixed strategy game in which a strategy is selected according to probability distribution among strategies. In the real world, there are various types of information security threats exist, so multiple information security measures should be considered to maintain the appropriate information security level of information systems. We assume that the defence ratio of the information security countermeasures is known, and we derive the optimal solution of the mixed strategy game using linear programming. The contributions of this study are as follows. First, we conduct analysis using real performance data of information security measures. Information security managers of organizations can use the methodology suggested in this study to make practical decisions when establishing investment portfolio for information security countermeasures. Second, the investment weight of information security countermeasures is derived. Since we derive the weight of each information security measure, not just whether or not information security measures have been invested, it is easy to construct an information security investment portfolio in a situation where investment decisions need to be made in consideration of a number of information security countermeasures. Finally, it is possible to find the optimal defence probability after constructing an investment portfolio of information security countermeasures. The information security managers of organizations can measure the specific investment effect by drawing out information security countermeasures that fit the organization's information security investment budget. Also, numerical examples are presented and computational results are analyzed. Based on the performance of various information security countermeasures: Firewall, IPS, and Antivirus, data related to information security measures are collected to construct a portfolio of information security countermeasures. The defence ratio of the information security countermeasures is created using a uniform distribution, and a coverage of performance is derived based on the report of each information security countermeasure. According to numerical examples that considered Firewall, IPS, and Antivirus as information security countermeasures, the investment weights of Firewall, IPS, and Antivirus are optimized to 60.74%, 39.26%, and 0%, respectively. The result shows that the defence probability of the organization is maximized to 83.87%. When the methodology and examples of this study are used in practice, information security managers can consider various types of information security measures, and the appropriate investment level of each measure can be reflected in the organization's budget.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.4
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• pp.855-861
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• 2017

Gordon & Loeb[1] suggested that the optimal level of investment decision of an enterprise is the point that the marginal benefit(MB) of information security investment is equal to the marginal cost(MC). However, many companies suffering from information security incidents are not aware of the fact that they are experiencing information security accidents and can not measure how much they are affected. In this paper, I propose a model of information security investment decision making under the incomplete information situation by modifying the Gordon & Loeb[1] model and compare the differences in investment level. Under the incomplete information situation the expected return from the information security investment tends to be lower than that of actual information security investment, and the level of investment is also less. This shows that if a third party such as the government gives accurate information such as the rate of incidents of information security accidents and the amount of damages, companies can expand their investment in information security.

• Information Systems Review
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• v.22 no.2
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• pp.201-217
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• 2020

Information security is an essential element not only to ensure the operation of the company and trust with customers but also to mitigate uncertain damage by preventing information data breach. Therefore, It is important to select appropriate information security countermeasures and determine the appropriate level of investment. This study presents a decision support model for the appropriate investment amount for each countermeasure as well as an optimal portfolio of information countermeasures within a limited budget. We analyze statistics on the types of information security breach by industry and derive an optimal portfolio of information security countermeasures by using genetic algorithms. The results of this study suggest guidelines for investing in information security countermeasures in various industries and help to support objective information security investment decisions.

• Journal of the Korean Operations Research and Management Science Society
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• v.34 no.3
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• pp.155-163
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• 2009

We develop a probability model to evaluate information security investment portfolios. We assume that organizations install portfolios of information security countermeasures to mitigate the damage such as loss of the transaction being processed, damage of hardware and data, etc. A queueing model and Its expected value analysis are used to derive the lost cost of transactions being processed, the replacement cost of hardwares, and the recovery cost of data. The net present value for each portfolio is derived and organizations can select the optimal information security investment portfolio by comparing portfolios.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.2
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• pp.109-116
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• 2010

We consider an information system where its throughput deteriorates due to security threats and evaluate information security investment portfolios. We assume that organizations adopt information security countermeasures (or portfolios consisted of countermeasures) to lessen the damage resulted from the productivity (or throughput) deterioration. A probability model is used to derive the system throughput and the average number of repairs according to the occurrence rate of security threats. Considering the revenue from throughput, the repair cost, and the investment for the security system, the net present value for each portfolio is derived. Organizations can compare information security investment portfolios and select the optimal portfolio.

• Information Systems Review
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• v.25 no.4
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• pp.27-45
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• 2023

The importance of information security has grown alongside the development of information and communication technology. However, companies struggle to select suitable countermeasures within their limited budgets. Sönmez and Kılıç (2021) proposed a model using AHP and mixed integer programming to determine the optimal investment combination for mitigating information security breaches. However, their model had limitations: 1) a lack of objective measurement for countermeasure efficacy against security threats, 2) unrealistic scenarios where risk reduction surpassed pre-investment levels, and 3) cost duplication when using a single countermeasure for multiple threats. This paper enhances the model by objectively quantifying countermeasure efficacy using the beta probability distribution. It also resolves unrealistic scenarios and the issue of duplicating investments for a single countermeasure. An empirical analysis was conducted on domestic SMEs to determine investment budgets and risk levels. The improved model outperformed Sönmez and Kılıç's (2021) optimization model. By employing the proposed effectiveness measurement approach, difficulty to evaluate countermeasures can be quantified. Utilizing the improved optimization model allows for deriving an optimal investment portfolio for each countermeasure within a fixed budget, considering information security costs, quantities, and effectiveness. This aids in securing the information security budget and effectively addressing information security threats.

• Journal of applied mathematics & informatics
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• v.28 no.3_4
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• pp.863-875
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• 2010

In this paper we apply the martingale approach, which has been widely used in mathematical finance, to investigate the optimal investment problem for an insurer under the criterion of mean-variance. When the risk and security assets are described by the L$\acute{e}$vy processes, the closed form solutions to the maximization problem are obtained. The mean-variance efficient strategies and frontier are also given.