• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.10
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• pp.99-107
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• 2008

In this paper, we analyse the vulnerability of spam attacks and develop the Spamtester to confirm these spam attacks in SIP-based VoIP networks. Although there are several spam attacks on VoIP networks, the detail information for the SPIT is not enough to confirm the procedure and the result of spam attacks on VoIP networks. Specially, the spam attacks through abnormal process are difficult to trace the sender of spam. Also, it is not easy to impose the legal restriction to the spammer because of lack of information for the spam attack. Therefore, on VoIP networks, the possible scenario and detail procedure for VoIP spam is needed to be confirmed. This paper designes and implementes the spamtester, which is helpful to protect VoIP networks from the spam attacks.

• KSCI Review
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• v.14 no.2
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• pp.215-224
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• 2006

Regarding a spam attack and the interception that a spinoff is largest among Vulnerability of VoIP at these papers study. Write scenario of a spam attack regarding VoIP Vulnerability, and execute Call spam. Instant Messaging spam, Presence spam attack. A spam attack is succeeded in laboratories, and prove. and confirm damage fact of a user in proposals of a spam interception way of VoIP service, 1) INVITE Request Flood Attack 2) Black/White list, 3) Traceback, 4) Black Hole-Sink Hole, 5) Content Filtering, 6) Consent based Communication, 7) Call act pattern investigation, 8) Reputation System Propose, and prove. Test each interception plan proposed in VoIP networks, and confirm security level of a spam interception. Information protection of VoIP service is enlarged at WiBro, BcN. and to realize Ubiquitous Security through result of research of this paper contribute, and may make.

• Journal of the Korea Society of Computer and Information
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• v.11 no.5 s.43
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• pp.241-250
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• 2006

Regarding a spam attack and the interception that a spinoff is largest among weakness of VoIP service at these papers study. Write scenario of a spam attack regarding VoIP service, and execute Call spam, Instant Messaging spam, Presence spam attack. A spam attack is succeeded in laboratories, and prove, and confirm damage fact of a user in proposals of a spam interception way of VoIP service, 1) INVITE Request Flood Attack 2) Black/White list, 3) Traceback, 4) Black Hole-Sink Hole, 5) Content Filtering, 6) Consent based Communication, 7) Call act pattern investigation, 8) Reputation System Propose, and prove. Test each interception plan proposed in VoIP networks, and confirm security level of a spam interception. Information protection of VoIP service is enlarged at WiBro, BcN, and to realize Ubiquitous Security through result of research of this paper contribute, and may make.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2006.06a
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• pp.471-474
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• 2006

기존 전화에 비해 저렴한 가격으로 서비스의 제공이 가능한 VoIP 서비스의 증가는 SIP 스팸이라는 역기능을 낳았다. SIP은 표준 VoIP 프로토콜로 현재 SIP 기반의 VoIP 서비스의 개발이 활발하게 진행 중에 있다. 이에 본 논문은 SIP 기반 VoIP 환경에서의 스팸 유형을 살펴본 후 이를 해결하기 위한 스팸 대응 기술로 기존의 이메일 스팸 대응 기술을 비교, 분석한다. 또한 이메일 스팸 대응 기술을 기반으로 제안된 현재 SIP 스팸 대응 기술을 알아보고 앞서 분석한 대응 기술의 SIP 기반 VoIP 환경에서의 적용 가능 여부를 생각하여 가장 적합한 스팸 대응 기술을 제시한다.

• Journal of the Korea Society for Simulation
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• v.16 no.3
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• pp.75-87
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• 2007

As the VoIP service quality is getting better and many shortcomings are being overcome, users are getting interested in this service. Also, there are several additional features that provide a convenience to users such as presence service, instant messaging service and so on. But, as there are always two sides of rein, some security issues have users hesitate to make use of it. This paper deals with one of the issues, the VoIP spam problem. We took into account the signal pattern of voice message in spam call and we have constructed voice signal models of normal call, normal call with noise and spam call. Each voice signal case is inserted into our spam decision algorithm which detects the spam calls based on the amount of information in the call signal. We made use of the DEVS-$Java^{TM}$ for our modeling and simulation. The contribution of this work is in suggestion of a way to detect voice spam call signal and testing of the method using modeling and simulation methodology.

• Convergence Security Journal
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• v.7 no.3
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• pp.109-120
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• 2007

VoIP service provides various functions that PSTN phone service hasn't been able to provide. Since it also has superiority in service charge, the number of user is increasing these days. When we think of the other side in cost aspect, the spam caller can also send his/her commercial message over phone line using more economic way. This paper presents the characteristics that should be considered to detect the spam call using greylisting method. We have explored static and dynamic characteristics in VoIP calls, and analyzed the relation among them. Especially, we have surveyed the authentication and charging method of Korean VoIP service provider. We have analyzed each charging method using our spam call simulation result, and derived the charging method that can be favored by spam caller. The contribution of the work is in analysis result of static aspect for SPIT Level calculation in greylisting method.

• 정보보호뉴스
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• s.127
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• pp.24-26
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• 2008

최근 인터넷전화(VoIP) 사용이 증가하고 있는 가운데, 지난 4월 7-8일 양일간 삼성동 코엑스에서 의미 있는 전시회가 개최됐다. KISA가 LG데이콤, 웨어플러스 등 3개 업체와 공동으로 지난 2006년부터 3개년 사업으로 추진하고 있는 VoIP의 정보보호 연구와 그 결과물인 정보보호 시스템 전시회가 그것이다. 특히 이번 전시회에서는 종단간(End to End) 보안통신을 지원하는 인터넷전화기기를 비롯해, 스팸 확산을 방지하는 VoIP 스팸 대응, VoIP 서비스망 보호를 위한 보안세션제어 시스템 등이 선보여, 차세대 IT 서비스로 주목받는 인터넷전화 서비스의 정보보호 수준을 한 단계 끌어올릴 것으로 평가받고 있다.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.3
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• pp.261-265
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• 2008

As increasing the user of VoIP service using ITSP(Internet Telephony Service Provider), the VoIP spam becomes a big problem. The spam used in the existing public telephone is detected by using the pattern inspection of call behavior because it is difficult to filter contents for the characteristic of real-time voice communication. However there is a false-positive problem. The threat on spam remains where spam with low threshold can't be detected or users share one number. In this paper, we propose anti-spam for VoIP based on luring test. The proposed method gives a user luring test and he/she can connect to a receiver if passing turing test. A ticket is given to a user that pass luring test and it reduces overhead of luring test in re-dial. The proposed method is implemented on ASUS WL-500G wireless router and Asterisk IP-PBX. Experimental results show the effectiveness of the proposed method.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10a
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• pp.185-186
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• 2007

ITSP(Internet Telephony Service Provider)를 이용한 VoIP 서비스의 사용자가 증가함에 따라 VoIP 스팸은 큰 문제로 대두되고 있다. 기존의 일반 전화 때부터 사용되던 스팸은 실시간적 음성 통신이라는 특성상 콘텐츠 필터링을 하기 어렵기 때문에 롤 행위 패턴 조사를 통해 스패머(Spammer)를 구분하고 있다. 그러나 잘못된 오판으로 인한 문제와 스팸으로 인식하는 임계값을 넘지 않는 한도의 스팸 전송, 그리고 여러 사용자가 하나의 번호를 공유하여 사용하는 경우에는 여전히 스팸의 위협이 남아 있다. 이에 본 논문에서는 튜링 테스트를 이용한 VoIP 스팸 방지를 제안한다. 제안된 방법은 송신자에게 튜링 테스트를 거치게 하고, 튜링 테스트를 통과한 사용자만 수신자와 연결이 되는 방식으로 동작한다. 또한 튜링 테스트를 통과한 정상적인 사용자에게는 티켓을 줌으로써 재발신시 거쳐야하는 튜링 테스트의 번거로움을 줄일 수 있다. 제안된 방법은 ASUS WL-500G 무선 공유기 및 Asterisk IP-PBX에서 구현되었고 실험을 통해 제안된 방법의 유효성을 검증하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8B
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• pp.630-636
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• 2012

In this paper, we propose an improved Multi Gray-Leveling scheme which reduces the problems of the existing Multi Gray-Leveling scheme suggested as a way of prevention against call spam in VoIP environment. The existing scheme having two different time period distinguishes the possibility of call spam by checking the call interval, so that it prevents the spammer's avoidance controlling the call interval. This is the strength of the existing one but it can misunderstand the normal user as a spammer due to taking long term time period. To solve this problem, this paper proposes the upgrade scheme which utilizes the receiver's action pattern as well as the caller's action pattern. It has such a good strength that can do gray leveling via the collected information in the database of VoIP service provider without user's direct involvement. Hence it can be a very effective way of VoIP spam detection.