• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.6
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• pp.1021-1031
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• 2023

State-sponsored cyber attacks are highly impactful because they are carried out to achieve pre-planned goals. As a defender, it is difficult to respond to them because of the large scale of the attack and the possibility that unknown vulnerabilities may be exploited. In addition, overreacting can reduce the availability of users and cause business disruption. Therefore, there is a need for a response policy that can effectively defend against attacks while ensuring user availability. To solve this problem, this paper proposes a method to collect the number of processes and sessions of defense assets in real time and use them for learning. Using this method to learn reinforcement learning-based policies on a cyber attack simulator, the attack duration based on 100 time-steps was reduced by 27.9 time-steps and 3.1 time-steps for two attacker models, respectively, and the number of "restore" actions that impede user availability during the defense process was also reduced, resulting in an overall better policy.

• Journal of Korea Multimedia Society
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• v.20 no.2
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• pp.279-288
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• 2017

Nowadays, nations cyber security capabilities play an important role in a nation's defense. Security-critical infrastructures such as national defenses, public services, and financial services are now exposed to Advanced Persistent Threats (APT) and their resistance to such attacks effects the nations stability. Currently Cyber Threat Intelligence (CTI) is widely used by organizations to mitigate and deter APT for its ability to proactively protect their assets by using evidence-based knowledge. The evidence-based knowledge information can be exchanged among organizations and used by the receiving party to strengthen their cyber security management. This paper will discuss on the business process reengineering of the CTI information exchange management for a nationwide scaled control and governance by the government to better protect their national information security assets.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.12
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• pp.5685-5700
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• 2018

Cyber intelligence, surveillance, and reconnaissance (ISR) has become more important than traditional military ISR. An agent used in cyber ISR resides in an enemy's networks and continually collects valuable information. Thus, this agent should be able to determine what is, and is not, useful in a short amount of time. Moreover, the agent should maintain a classification rate that is high enough to select useful data from the enemy's network. Traditional feature selection algorithms cannot comply with these requirements. Consequently, in this paper, we propose an effective hybrid feature selection method derived from the filter and wrapper methods. We illustrate the design of the proposed model and the experimental results of the performance comparison between the proposed model and the existing model.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.5
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• pp.1039-1055
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• 2012

It is required for us to enhance the national cyber capability as the worldwide countries have been doing effort to strengthen their cyber capabilities. However, we are encountering the difficulty in estimating national cyber capability due to the absence of any cyber capability assessment methodology. This paper presents the national cyber capability assessment methodology which is used for settle up national cyber policy. We also introduce the result of five major nations(US, China, Japan, Russia, Korea)' cyber capability assessment using the proposed methodology. The methodology is developed using open data and includes three areas; base capability, attack capability and defense capability. The assessment result shows the in the order of US, China, Korea, Russia, Japan. As the analysis of that result, in order to enhance the our cyber capability, we recommend that first, cyber budget and human resources for the base capability should be more invested, second, the strategy for attack capability enhancement is strongly required and lastly, the patch ratio and security monitoring level should be upgraded.

• Journal of Internet Computing and Services
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• v.23 no.5
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• pp.87-101
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• 2022

Cyber-attacks occur in the blink of an eye in cyberspace, and the damage is increasing all over the world. Therefore, it is necessary to develop a cyber common operational picture that can grasp the various assets belonging to the 3rd layer of cyberspace from various perspectives. By applying the method for grasping battlefield information used by the military, it is possible to achieve optimal cyberspace situational awareness. Therefore, in this study, the visualization screens necessary for the cyber common operational picture are identified and the criteria (response speed, user interface, object symbol, object size) are investigated. After that, the framework is designed by applying the identified and investigated items, and the visualization screens are implemented accordingly. Finally, among the criteria investigated by the visualization screen, an experiment is conducted on the response speed that cannot be recognized by a photograph. As a result, all the implemented visualization screens met the standard for response speed. Such research helps commanders and security officers to build a cyber common operational picture to prepare for cyber-attacks.

• Journal of Internet Computing and Services
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• v.22 no.6
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• pp.33-40
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• 2021

Automatic Speech Recognition(ASR) is a technology that analyzes human speech sound into speech signals and then automatically converts them into character strings that can be understandable by human. Speech recognition technology has evolved from the basic level of recognizing a single word to the advanced level of recognizing sentences consisting of multiple words. In real-time voice conversation, the high recognition rate improves the convenience of natural information delivery and expands the scope of voice-based applications. On the other hand, with the active application of speech recognition technology, concerns about related cyber attacks and threats are also increasing. According to the existing studies, researches on the technology development itself, such as the design of the Automatic Speaker Verification(ASV) technique and improvement of accuracy, are being actively conducted. However, there are not many analysis studies of attacks and threats in depth and variety. In this study, we propose a cyber attack model that bypasses voice authentication by simply manipulating voice frequency and voice speed for AI voice recognition service equipped with automated identification technology and analyze cyber threats by conducting extensive experiments on the automated identification system of commercial smartphones. Through this, we intend to inform the seriousness of the related cyber threats and raise interests in research on effective countermeasures.

• Journal of Information Technology Services
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• v.12 no.4
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• pp.77-90
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• 2013

As Cyber threats are rising, the scope of information Security (IS) is extending from technical protection of a single information system to organizational comprehensive IS capability. The ministry of National Defense (MND) has established the IS evaluation for defense organization in 'the Directive for Defense Informatization Affairs.' However, no information about an evaluation method, process and organization is provided. We surveyed information security management system (ISMS) and related best practices in public sector and other countries, and analysed the military information security affairs. Thus, this paper recommends the IS evaluation method and process. The trial IS evaluation is in progress this year and the MND will expand this IS evaluation to the entire organization.

• Convergence Security Journal
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• v.19 no.2
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• pp.59-72
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• 2019

In this day and age physical and cyber boundaries have converged due to the development of new technologies, such as the Internet of Things (IoT) and the Cyber Physical System (CPS). As the relationship between physical system and cyber technology strengthens, more diverse and complex forms of risk emerge. As a result, it is becoming difficult for single organization or government to fully handle this situation alone and cooperation based on information sharing and the strengthening of active defense systems are needed. Shifting to a system in which information suitable for various entities can be shared and automatically responded to is also necessary. Therefore, this study tries to find improvements for the current system of threat information collecting and sharing that can actively and practically maintain cyber defense posture, focusing particularly on the structuring of information sharing platforms. To achieve our objective, we use a risk communication theory from the safety field and propose a new platform by combining an action-oriented security process model.

• ETRI Journal
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• v.41 no.5
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• pp.585-598
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• 2019

A cyber-physical system (CPS) is a new mechanism controlled or monitored by computer algorithms that intertwine physical and software components. Advanced persistent threats (APTs) represent stealthy, powerful, and well-funded attacks against CPSs; they integrate physical processes and have recently become an active research area. Existing offensive and defensive processes for APTs in CPSs are usually modeled by incomplete information game theory. However, honeypots, which are effective security vulnerability defense mechanisms, have not been widely adopted or modeled for defense against APT attacks in CPSs. In this study, a honeypot game-theoretical model considering both low- and high-interaction modes is used to investigate the offensive and defensive interactions, so that defensive strategies against APTs can be optimized. In this model, human analysis and honeypot allocation costs are introduced as limited resources. We prove the existence of Bayesian Nash equilibrium strategies and obtain the optimal defensive strategy under limited resources. Finally, numerical simulations demonstrate that the proposed method is effective in obtaining the optimal defensive effect.

• Annual Conference of KIPS
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• 2017.11a
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• pp.235-238
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• 2017

최근에는 랜섬웨어의 일종인 '워너크라이' 등의 바이러스로 인한 피해도 기하급수적으로 증가하고, 그 수법도 사용자가 파일에 접근하면 감염되던 형태에서 인터넷에 접속되기만 하면 감염되는 형태로 진화하면서 사이버전에 사용되어질 수 있는 사이버 공격에 대응하는 방어 및 회복 방책에 대한 관심이 한층 더 증폭되고 있다. 하지만 일반적으로 방어, 회복 등의 대응 과정은 공격의 피해를 평가하여 결과로 산출된 피해 정도를 전제 조건으로 가지기 때문에 먼저 해킹 공격의 피해를 평가하여야 한다. 본 논문에서는 사이버전에서 사용되어질 수 있는 해킹 공격 및 위협의 피해를 공격의 종류별로 평가하기 위해, 피해 정도를 수치화할 수 있는지의 여부 등을 기준으로 하여 총 3가지 Interruption, Modification, Interception로 구성된 해킹 공격의 분류 체계를 제시한다.