• 한국컴퓨터정보학회논문지
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• 제24권9호
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• pp.35-42
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• 2019

In this paper, we propose an approach to apply network-based moving target defense into Internet of Things (IoT) networks. The IoT is a technology that provides the high interconnectivity of things like electronic devices. However, cyber security risks are expected to increase as the interconnectivity of such devices increases. One recent study demonstrated a man-in-the-middle attack in the statically configured IoT network. In recent years, a new approach to cyber security, called the moving target defense, has emerged as a potential solution to the challenge of static systems. The approach continuously changes system's attack surface to prevent attacks. After analyzing IPv4 / IPv6-based moving target defense schemes and IoT network-related technologies, we present our approach in terms of addressing systems, address mutation techniques, communication models, network configuration, and node mobility. In addition, we summarize the direction of future research in relation to the proposed approach.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권3호
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• pp.1063-1075
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• 2022

In recent years, container techniques have been broadly applied to cloud computing systems to maximize their efficiency, flexibility, and economic feasibility. Concurrently, studies have also been conducted to ensure the security of cloud computing. Among these studies, moving-target defense techniques using the high agility and flexibility of cloud-computing systems are gaining attention. Moving-target defense (MTD) is a technique that prevents various security threats in advance by proactively changing the main attributes of the protected target to confuse the attacker. However, an analysis of existing MTD techniques revealed that, although they are capable of deceiving attackers, MTD techniques have practical limitations when applied to an actual cloud-computing system. These limitations include resource wastage, management complexity caused by additional function implementation and system introduction, and a potential increase in attack complexity. Accordingly, this paper proposes a software-defined MTD system that can flexibly apply and manage existing and future MTD techniques. The proposed software-defined MTD system is designed to correctly define a valid mutation range and cycle for each moving-target technique and monitor system-resource status in a software-defined manner. Consequently, the proposed method can flexibly reflect the requirements of each MTD technique without any additional hardware by using a software-defined approach. Moreover, the increased attack complexity can be resolved by applying multiple MTD techniques.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권10호
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• pp.4157-4175
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• 2020

Moving target defense, as a 'game-changing' security technique for network warfare, realizes proactive defense by increasing network dynamics, uncertainty and redundancy. How to select the best countermeasure from the candidate countermeasures to maximize defense payoff becomes one of the core issues. In order to improve the dynamic analysis for existing decision-making, a novel approach of selecting the optimal countermeasure using game theory is proposed. Based on the signal game theory, a multi-stage adversary model for dynamic defense is established. Afterwards, the payoffs of candidate attack-defense strategies are quantified from the viewpoint of attack surface transfer. Then the perfect Bayesian equilibrium is calculated. The inference of attacker type is presented through signal reception and recognition. Finally the countermeasure for selecting optimal defense strategy is designed on the tradeoff between defense cost and benefit for dynamic network. A case study of attack-defense confrontation in small-scale LAN shows that the proposed approach is correct and efficient.

• 한국컴퓨터정보학회논문지
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• 제23권9호
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• pp.57-64
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• 2018

In recent years, a new approach to cyber security, called the moving target defense, has emerged as a potential solution to the challenge of static systems. In this paper, we design a protected server network with a large number of decoys to anonymize the protected servers that dynamically mutate their IP address and port numbers according to Hidden Tunnel Networking, which is a network-based moving target defense scheme. In the network, a protected server is one-to-one mapped to a decoy-bed that generates a number of decoys, and the decoys share the same IP address pool with the protected server. First, the protected server network supports mutating the IP address and port numbers of the protected server very frequently regardless of the number of decoys. Second, it provides independence of the decoy-bed configuration. Third, it allows the protected servers to freely change their IP address pool. Lastly, it can reduce the possibility that an attacker will reuse the discovered attributes of a protected server in previous scanning. We believe that applying Hidden Tunnel Networking to protected servers in the proposed network can significantly reduce the probability of the protected servers being identified and compromised by attackers through deploying a large number of decoys.

• 한국군사과학기술학회지
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• 제20권3호
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• pp.369-375
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• 2017

One of good DF(Direction Finding) methods is based on TDOA(Time Difference of Arrival) estimation when finding underwater moving target. For small DF error, high time resolution A/D(Analog-to-digital) conversion board and long baseline are needed. But the result of sea trial about close-range and high speed moving target, spatial correlation coefficient and appeared poor properties below 0.3 when hydrophone arrangement are separated over 6 ${\lambda}$ because of underwater fading channel. And we also find out that the distance between hydrophone should be under 4 ${\lambda}$ apart to take advantage of spatial correlation coefficient gain and performance of DF in underwater moving channel environments.

• 한국컴퓨터정보학회논문지
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• 제22권10호
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• pp.83-92
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• 2017

Reconnaissance is performed gathering information from a series of scanning probes where the objective is to identify attributes of target hosts. Network reconnaissance of IP addresses and ports is prerequisite to various cyber attacks. In order to increase the attacker's workload and to break the attack kill chain, a few proactive techniques based on the network-based moving target defense (NMTD) paradigm, referred to as IP address mutation/randomization, have been presented. However, there are no commercial or trial systems deployed in real networks. In this paper, we propose a threat model and the request for requirements for developing NMTD techniques. For this purpose, we first examine the challenging problems in the NMTD mechanisms that were proposed for the legacy TCP/IP network. Secondly, we present a threat model in terms of attacker's intelligence, the intended information scope, and the attacker's location. Lastly, we provide seven basic requirements to develop an NMTD mechanism for the legacy TCP/IP network: 1) end-host address mutation, 2) post tracking, 3) address mutation unit, 4) service transparency, 5) name and address access, 6) adaptive defense, and 7) controller operation. We believe that this paper gives some insight into how to design and implement a new NMTD mechanism that would be deployable in real network.

• 한국컴퓨터정보학회논문지
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• 제24권10호
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• pp.25-32
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• 2019

본 논문에서는 보호대상 서버 네트워크에 디코이 트랩을 통한 공격 표면 확장의 적용 방법을 제안한다. 보호대상 서버 네트워크는 많은 수의 디코이들과 보호대상 서버로 구성되며, 각 보호대상 서버는 Hidden Tunner Networking이라는 네트워크 기반 이동 표적 방어 기법에 따라 IP 주소와 포트 번호를 변이한다. 이동 표적 방어는 공격을 막기 위하여 지속적으로 시스템의 공격 표면을 변경하는 사이버 보안에서의 새로운 접근방법이다. 공격 표면 확장은 공격을 막기 위해 디코이와 디코이 그룹을 활용하는 접근방법이다. 제안하는 방법에서는 공격자가 디코이 트랩에서 공격자의 모든 시간과 노력을 허비하도록 커스텀 체인과 RETURN 타켓을 사용하여 보호대상 서버의 NAT 테이블을 수정한다. 본 논문에서는 제안하는 방법이 적용되기 전과 후에 보호대상 서버 네트워크에서의 공격자 성공률을 수식으로 계산한다. 제안하는 방법은 보호대상 서버가 공격자에 의해 식별되고 공격당할 확률을 현저히 줄일 것으로 기대된다.

• 대한원격탐사학회지
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• 제22권3호
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• pp.229-234
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• 2006

In tactical theater, it is crucial to detect ground moving targets and to locate them precisely. This problem can be resolved by using SAR (Synthetic Aperture Radar) sensors providing GMTI (Ground Moving Target Indication) capability. In general, to implement a robust GMTI sensor is not simple because of the strong competitions between target signals and clutter signals from the ground, and low speed of moving targets. Contrary to the case that a delay canceller is mostly suitable for ground surveillance radars, DPCA (Displaced Phase Centered Antenna) or STAP (Space Time Adaptive Processing) techniques have been widely adapted for GMTI function of modern airborne radars. In this paper, a new scheme of DPCA using two passive antennas with vertical separation is proposed, which also provides good clutter cancellation performance. The proposed scheme realizes full azimuth coverage for DPCA operation on an airborne platform, which is impossible with classical DPCA configuration. Simulations using various conditions have been performed to validate the proposed scheme, and the results are acceptable.

• 한국군사과학기술학회지
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• 제21권2호
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• pp.141-146
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• 2018

The Ground Moving Target Indication(GMTI) technique can detect the moving targets on land using its Doppler returns. Also, the GMTI system can work in night regardless of the weather condition because it is an active sensor that uses the electromagnetic waves as its source. In order to develop the GMTI system, Constant False Alarm Rate(CFAR) threshold optimization is important because the main performances like detection probability, false alarm rate and Minimum Detectable Velocity(MDV) are related deeply with CFAR threshold. These key variables are used to calculate CFAR threshold and then trade-off between the variables is performed. In this paper, CFAR threshold optimization procedures are introduced, and the optimization results are demonstrated.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2018년도 추계학술발표대회
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• pp.158-161
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• 2018

2011년 미국에서 최초로 소개된 후 기존 보안 기술과 다른 새로운 정보시스템 보호 기술로 Moving Target Defense(MTD)가 활발히 연구 되고 있다. MTD는 시스템의 구성 요소들을 뷸규칙적이고 동적으로 변화시켜 공격표면(Attack surface)을 줄임으로써 외부 공격에 대한 보안성을 높인다. 주로 시스템 정보를 수집 및 분석하여 공격하는 보안 위협들에 효과적이며 특히 지능형 지속 보안 위협(Advanced Persistent Threat), 킬 체인(Kill-Chain) 보안에 뛰어난 성능을 기대할 수 있다. 최근 MTD 시스템 구현 및 개발로 상용화가 시작되었으나 MTD 활용을 통해 어느 정도의 보안성 및 효율성을 가지는지에 대한 성능 평가인증, 시험지침 등이 표준화 되어있지 않아 기준이 모호한 실정이다. 본 논문에서는 이러한 최근 MTD 이슈에 대해 살펴보고 MTD와 연관 되어있는 각 분야에 어떤 평가인증 요구사항들이 있는지 분석한다. 이를 통해 MTD에 어떠한 평가인증 요구사항이 있는지 도출하여 앞으로 MTD 평가인증 표준화 참고 및 활용에 기여 할 수 있을 것으로 전망한다.