• Convergence Security Journal
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• v.19 no.2
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• pp.11-19
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• 2019

The blockchain is a technique for managing transaction data in distributed computing manner without the involvement of central trust authority. The blockchain has been used in various area such as manufacturing, culture, and public as well as finance because of its advantage of the security, efficiency and applicability. In the blockchain, it was considered safe against 51% attack because the adversary could not have more than 50% hash power. However, there have been cases caused by large-scale computing attacks such as 51% and selfish mining attack, and the frequency of these attacks is increasing. In addition, since the development of quantum computers can hold exponentially more information than their classical computer, it faces a new type of threat using quantum algorithms. In this paper, we perform the security analysis of blockchain attacks composing the large computing capabilities including quantum computing attacks. Finally, we suggest the technologies and future direction of the blockchain development in order to be safe against large-scale computing attacks.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1568-1570
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• 2005

The internet is already a part of life. It is very convenient and people can do almost everything with internet that should be done in real life. Along with the increase of the number of internet user, various network attacks through the internet have been increased as well. Also, Large-scale network attacks are a cause great concern for the computer security communication. These network attack becomes biggest threat could be down utility of network availability. Most of the techniques to detect and analyze abnormal traffic are statistic technique using mathematical modeling. It is difficult accurately to analyze abnormal traffic attack using mathematical modeling, but network simulation technique is possible to analyze and simulate under various network simulation environment with attack scenarios. This paper performs modeling and simulation under virtual network environment including $NGSS^{1}$ system to analyze abnormal traffic-flooding attack.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.3
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• pp.916-937
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• 2023

Most of the existing Distributed Denial-of-Service mitigation schemes in Software-Defined Networking are only implemented in the network domain managed by a single controller. In fact, the zombies for attackers to launch large-scale DDoS attacks are actually not in the same network domain. Therefore, abnormal traffic of DDoS attack will affect multiple paths and network domains. A single defense method is difficult to deal with large-scale DDoS attacks. The cooperative defense of multiple domains becomes an important means to effectively solve cross-domain DDoS attacks. We propose an efficient multi-domain DDoS cooperative defense mechanism by integrating blockchain and SDN architecture. It includes attack traceability, inter-domain information sharing and attack mitigation. In order to reduce the length of the marking path and shorten the traceability time, we propose an AS-level packet traceability method called ASPM. We propose an information sharing method across multiple domains based on blockchain and smart contract. It effectively solves the impact of DDoS illegal traffic on multiple domains. According to the traceability results, we designed a DDoS attack mitigation method by replacing the ACL list with the IP address black/gray list. The experimental results show that our ASPM traceability method requires less data packets, high traceability precision and low overhead. And blockchain-based inter-domain sharing scheme has low cost, high scalability and high security. Attack mitigation measures can prevent illegal data flow in a timely and efficient manner.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.6
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• pp.2881-2894
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• 2018

Cyber attacks are increasing continuously. On average about one million malicious codes appear every day, and attacks are expanding gradually to IT convergence services (e.g. vehicles and television) and social infrastructure (nuclear energy, power, water, etc.), as well as cyberspace. Analysis of large-scale cyber incidents has revealed that most attacks are started by PCs infected with malicious code. This paper proposes a method of detecting an attack IP automatically by analyzing the characteristics of the e-mail transfer path, which cannot be manipulated by the attacker. In particular, we developed a system based on the proposed model, and operated it for more than four months, and then detected 1,750,000 attack IPs by analyzing 22,570,000 spam e-mails in a commercial environment. A detected attack IP can be used to remove spam e-mails by linking it with the cyber removal system, or to block spam e-mails by linking it with the RBL(Real-time Blocking List) system. In addition, the developed system is expected to play a positive role in preventing cyber attacks, as it can detect a large number of attack IPs when linked with the portal site.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.1
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• pp.71-77
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• 2006

Several network attacks, such as distributed denial of service (DDoS) attack, present a very serious threat to the stability of the internet. The threat posed by network attacks on large networks, such as the internet, demands effective detection method. Therefore, a simple intrusion detection system on large-scale backbone network is needed for the sake of real-time detection, preemption and detection efficiency. In this paper, in order to discriminate attack traffic from legitimate traffic on backbone links, we suggest a relatively simple statistical measure, entropy, which can track value frequency. Den is conspicuous distinction of entropy values between attack traffic and legitimate traffic. Therefore, we can identify what kind of attack it is as well as detecting the attack traffic using entropy value.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.10
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• pp.2731-2749
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• 2012

Sybil attack has been proved effective in mitigating the P2P botnet, but the impacts of some important parameters were not studied, and no model to estimate the effectiveness was proposed. In this paper, taking Kademlia-based botnets as the example, the model which has the upper and lower bound to estimate the mitigating performance of the Sybil attack is proposed. Through simulation, how three important factors affect the performance of the Sybil attack is analyzed, which is proved consistent with the model. The simulation results not only confirm that for P2P botnets in large scale, the Sybil attack is an effective countermeasure, but also imply that the model can give suggestions for the deployment of Sybil nodes to get the ideal performance in mitigating the P2P botnet.

• Journal of Korea Multimedia Society
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• v.9 no.8
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• pp.1037-1044
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• 2006

It's difficult to check cyber attacks and the performance of a security system in a real large-scale network. Generally, a new security system or the effect of a new security attack are checked by simulation. We use SSFNet to simulate our security system and cyber attack. SSFNet is an event-driven simulation tools based on process, which has a strength to be capable of expressing a large-scale network. But it doesn't offer any API's which can manipulate not only the related function of security but also the packet. In this paper, we developed a firewall and IPS class, used for a security system, and added to them components of SSFNet. The firewall is modelled a security system based on packet filtering. We checked the function of the firewall and the IPS with network modelled as using our SSFNet. The firewall blocks packets through rules of an address and port of packets. The result of this simulation shows that we can check a status of packets through a log screen of IPS installed in a router and confirm abnormal packet to be dropped.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.642-645
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• 2012

MANET has disadvantage for information intrusion caused from non-infra structure. That is based on mixed problems caused from terminal devices has no capability of various resources using abilities to run intrusion prevention function, and also from difficulty of no easy using infra structural server like as firewall. In this paper, transmission performances, be effected from information intrusion and IDS(Intrusion Detection System), are analyzed for large scale MANET, and weakness from information intrusion of MANET are studied. This study is for large scale MANET which has some large communication area and lots of nodes, voice traffic, based on VoIP protocols, is considered as application services be transmitted over MANETs. Computer simulation using NS-2 is used to measure and show MOS and call connection ratios.

• The Journal of the Korea Contents Association
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• v.21 no.2
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• pp.587-593
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• 2021

In this thesis, we will break away from the classic DDoS response system for large-scale denial-of-service attacks that develop day by day, and effectively endure intelligent denial-of-service attacks by utilizing artificial intelligence-based technology, one of the core technologies of the 4th revolution. A possible service model development plan was proposed. That is, a method to detect denial of service attacks and minimize damage through machine learning artificial intelligence learning targeting a large amount of data collected from multiple security devices and web servers was proposed. In particular, the development of a model for using artificial intelligence technology is to detect a Western service attack by focusing on the fact that when a service denial attack occurs while repeating a certain traffic change and transmitting data in a stable flow, a different pattern of data flow is shown. Artificial intelligence technology was used. When a denial of service attack occurs, a deviation between the probability-based actual traffic and the predicted value occurs, so it is possible to respond by judging as aggressiveness data. In this paper, a service denial attack detection model was explained by analyzing data based on logs generated from security equipment or servers.

• Convergence Security Journal
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• v.16 no.6_1
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• pp.43-50
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• 2016

As North Korea has a sufficient ability to attack our society's vulnerable computer network, various large-scale cyber attacks are expected to be tried. North Korea's cyber military strength is known a world-class level. The number of its cyber agents is increasing consistently. Recently North Korea's cyber attack has been made regardless of trick and target. But up to now North Korea's cyber attack is more of an exploration than a real attack. Its purpose was to check how fast Korea found a problem and recovered from it. In future, cyber attack that damages substantially is highly probable. In case of an attack against national infrastructure like traffic, financial and energy services, the extent of the damage will be great beyond imagination. In this paper, characteristics of recent North Korea's cyber attack is addressed in depth and countermeasures such as the enactment of cyber terror prevention law, simulation training enforcement, private and public cooperation system construction, cyber security infrastructure expansion, etc. are proposed.