• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.265-268
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• 2011

Voice over Internet protocol(VoIP) is support a VoIP service as All-IP method and Gateway method etc. All-IP method to the unit in an Internet environment by applying both the IP service is an VoIP system. Gateway method, using a normal phone call in a way that the Internet is using VoIP. In this paper, scanning and analyze the vulnerability for VoIP systems and networks from All-IP method and the Gateway method In the test bed. All-IP method and Gateway method found in the VoIP vulnerabilities, hacking attack, a denial of service attacks and VoIP spam attacks are carried out. Through analysis of post-attack security measures is proposed.

• International Journal of Advanced Culture Technology
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• v.9 no.4
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• pp.288-294
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• 2021

There are various ways to be infected with malicious code due to the increase in Internet use, such as the web, affiliate programs, P2P, illegal software, DNS alteration of routers, word processor vulnerabilities, spam mail, and storage media. In addition, malicious codes are produced more easily than before through automatic generation programs due to evasion technology according to the advancement of production technology. In the past, the propagation speed of malicious code was slow, the infection route was limited, and the propagation technology had a simple structure, so there was enough time to study countermeasures. However, current malicious codes have become very intelligent by absorbing technologies such as concealment technology and self-transformation, causing problems such as distributed denial of service attacks (DDoS), spam sending and personal information theft. The existing malware detection technique, which is a signature detection technique, cannot respond when it encounters a malicious code whose attack pattern has been changed or a new type of malicious code. In addition, it is difficult to perform static analysis on malicious code to which code obfuscation, encryption, and packing techniques are applied to make malicious code analysis difficult. Therefore, in this paper, a method to detect malicious code through dynamic analysis and static analysis using Trojan-type Downloader/Dropper malicious code was showed, and suggested to malicious code detection and countermeasures.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.4
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• pp.737-744
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• 2012

Recently VoIP has provided voice(both wired and wireless from IP-based) as well as the transmission of multimedia information. VoIP used All-IP type, Gateway type, mVoIP etc. Wired and wireless VoIP has security vulnerabilities that VoIP call control signals, illegal eavesdropping, service misuse attacks, denial of service attack, as well as wireless vulnerabilities etc. from WiFi Zone. Therefore, the analysis of security vulnerabilities in wired and wireless VoIP and hacking incidents on security measures for research and study is needed. In this paper, VoIP (All-IP type, and for Gateway type) for system and network scanning, and, IP Phone to get the information and analysis of the vulnerability. All-IP type and Gateway type discovered about the vulnerability of VoIP hacking attacks (Denial of Service attacks, VoIP spam attacks) is carried out. And that is a real VoIP system installed and operated in the field of security measures through research and analysis is proposed.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.4
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• pp.51-61
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• 2009

Recently, the cyber-attacks using botnets are being increased, Because these attacks pursue the money, the criminal aspect is also being increased, There are spreading of spam mail, DDoS(Distributed Denial of Service) attacks, propagations of malicious codes and malwares, phishings. leaks of sensitive informations as cyber-attacks that used botnets. There are many studies about detection and mitigation techniques against centralized botnets, namely IRC and HITP botnets. However, P2P botnets are still in an early stage of their studies. In this paper, we analyzed the traffics of the Peacomm bot that is one of P2P-based storm bot by using honeynet which is utilized in active analysis of network attacks. As a result, we could see that the Peacomm bot sends a large number of UDP packets to the zombies in wide network through P2P. Furthermore, we could know that the Peacomm bot makes the scale of botnet maintained and extended through these results. We expect that these results are used as a basis of detection and mitigation techniques against P2P botnets.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.6A
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• pp.107-114
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• 2008

The Bot is a kind of worm/virus that can be used to launch the distributed denial-of-service(DDoS) attacks or send massive amount of spam e-mails, etc. A lot of organizations make an effort to counter the Botnet's attacks. In Korea, we use DNS sinkhole system to protect from the Botnet's attack, while in Japan "so called" CCC(Cyber Clean Center) has been developed to protect from the Botnet's attacks. But in case of DNS sinkhole system, there is a problem since it cannot cure the Bot infected PCs themselves and in case of CCC there is a problem since only 30% of users with the Botnet-infected PCs can cooperate to cure themself. In this paper we propose a new method that prevent the Botnet's attacks and cure the Bot-infected PCs at the same time.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.4
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• pp.761-770
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• 2012

CAPTCHAs(Completely Automated Public Turing tests to tell Computer and Human Apart) have been widely used for preventing the automated attacks such as spam mails, DDoS attacks, etc.. In the early stages, the text-based CAPTCHAs that were made by distorting random characters were mainly used for frustrating automated-bots. Many researches, however, showed that the text-based CAPTCHAs were breakable via AI or image processing techniques. Due to the reason, the image-based CAPTCHAs, which employ images instead of texts, have been considered and suggested. In many image-based CAPTCHAs, however, the huge number of source images are required to guarantee a fair level of security. In 2008, Kang et al. suggested a new image-based CAPTCHA that uses test images made by composing multiple source images, to reduce the number of source images while it guarantees the security level. In their paper, the authors showed the convenience of their CAPTCHA in use through the use study, but they did not verify its security level. In this paper, we verify the security of the image-based CAPTCHA suggested by Kang et al. by performing several attacks in various scenarios and consider other possible attacks that can happen in the real world.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.12
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• pp.2689-2694
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• 2012

In recent years, cyber crimes were intended to get financial benefits through malicious attempts such as DDoS attacks, stealing financial information and spam. Botnets, a network composed of large pool of infected hosts, lead such malicious attacks. The botnets have adopted several evasion techniques and variations. Therefore, it is difficult to detect and eliminate them. Current botnet solutions use a signature based detection mechanism. Furthermore, the solutions cannot cover broad areas enough to detect world-wide botnets. In this paper, we propose IRC (Internet Relay Chat) that is used to control the botnet communication in a session channel of IRC servers connected through the analysis of the relationship of the channel and the connection with the server bot-infected hosts and how to detect.

• Journal of the Korea Society of Computer and Information
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• v.24 no.5
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• pp.27-33
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• 2019

One of serious security threats is a botnet-based attack. A botnet in general consists of numerous bots, which are computing devices with networking function, such as personal computers, smartphones, or tiny IoT sensor devices compromised by malicious codes or attackers. Such botnets can launch various serious cyber-attacks like DDoS attacks, propagating mal-wares, and spreading spam e-mails over the network. To establish a botnet, attackers usually inject malicious URLs into web source codes stealthily by using data hiding methods like Javascript obfuscation techniques to avoid being discovered by traditional security systems such as Firewall, IPS(Intrusion Prevention System) or IDS(Intrusion Detection System). Meanwhile, it is non-trivial work in practice for software developers to manually find such malicious URLs which are hidden in numerous web source codes stored in web servers. In this paper, we propose a security defense system to discover such suspicious, malicious URLs hidden in web source codes, and present experiment results that show its discovery performance. In particular, based on our experiment results, our proposed system discovered 100% of URLs hidden by Javascript encoding obfuscation within sample web source files.

• International Journal of Computer Science & Network Security
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• v.22 no.2
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• pp.153-158
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• 2022

The Internet of Things (IoT) has gotten a lot of research attention in recent years. IoT is seen as the internet's future. IoT will play a critical role in the future, transforming our lifestyles, standards, and business methods. In the following years, the use of IoT in various applications is likely to rise. In the world of information technology, cyber security is critical. In today's world, protecting data has become one of the most difficult tasks. Different type of emerging cyber threats such as malicious, network based and abuse of network have been identified in the IoT. These can be done by virus, Phishing, Spam and insider abuse. This paper focuses on emerging threats, various challenges and vulnerabilities which are faced by the cyber security in the field of IoT and its applications. It focuses on the methods, ethics, and trends that are reshaping the cyber security landscape. This paper also focuses on an attempt to classify various types of threats, by analyzing and characterizing the intruders and attacks facing towards the IoT devices and its services.

• Journal of the Korea Society of Computer and Information
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• v.17 no.3
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• pp.113-120
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• 2012

VoIP provides voice data service using existing IP networks and has received much attention recently. VoIP service has a variety of security vulnerabilities. Types of main attacks on VoIP service are tapping/interception, DoS attacks, spam, misuse of service attacks and the like. Of these, confidential information leak because of tapping/interception has been considered as a critical problem. Encryption techniques, such as SRTP and ZRTP, are mostly used to prevent tap and intercept on VoIP media information. In general, VoIP service has two service scenarios. First, VoIP service operates within a single private network. Second, VoIP service operates between different private networks. Both SRTP and ZRTP for VoIP media information within a single private network can perform encryption. But they can not perform encryption between different private networks. In order to solve this problem, in this paper, we modify SRTP protocol. And then, we propose an encryption method that can perform encryption of VoIP media information between the different private networks.