• ETRI Journal
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• 제37권2호
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• pp.348-358
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• 2015

Mobile devices have been widespread and become very popular with connectivity to the Internet, and a lot of desktop PC applications are now aggressively ported to them. Unfortunately, mobile devices are often vulnerable to malicious attacks due to their common usage and connectivity to the Internet. Therefore, the demands on the development of mobile security systems increase in accordance with advances in mobile computing. However, it is very hard to run a security program on a mobile device all of the time due the device's limited computational power and battery life. To overcome these problems, we propose a novel mobile security scheme that migrates heavy computations on mobile devices to cloud servers. An efficient data transmission scheme for reducing data traffic between devices and servers over networks is introduced. We have evaluated the proposed scheme with a mobile device in a cloud environment, whereby it achieved a maximum speedup of 13.4 compared to a traditional algorithm.

• ETRI Journal
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• 제37권1호
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• pp.77-87
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• 2015

In wireless networks, cooperation is necessary for many protocols, such as routing, clock synchronization, and security. It is known that cooperator nodes suffer greatly from problems such as increasing energy consumption. Therefore, rational nodes have no incentive to cooperatively forward traffic for others. A rational node is different from a malicious node. It is a node that makes the best decision in each state (cooperate or non-cooperate). In this paper, game theory is used to analyze the cooperation between nodes. An evolutionary game has been investigated using two nodes, and their strategies have been compared to find the best one. Subsequently, two approaches, one based on a genetic algorithm (GA) and the other on learning automata (LA), are presented to incite nodes for cooperating in a noisy environment. As you will see later, the GA strategy is able to disable the effect of noise by using a big enough chromosome; however, it cannot persuade nodes to cooperate in a noisefree environment. Unlike the GA strategy, the LA strategy shows good results in a noise-free environment because it has good agreement in cooperation-based strategies in both types of environment (noise-free and noisy).

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권9호
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• pp.4529-4548
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• 2016

DDoS attacks have had a devastating effect on the Internet, which can cause millions of dollars of damage within hours or even minutes. In this paper we propose a practical dynamic defense approach that overcomes the shortage of static defense mechanisms. Our approach employs a group of SDN-based proxy switches to relay data flow between users and servers. By substituting backup proxy switches for attacked ones and reassigning suspect users onto the new proxy switches, innocent users are isolated and saved from malicious attackers through a sequence of remapping process. In order to improve the speed of attacker segregation, we have designed and implemented an efficient greedy algorithm which has been demonstrated to have little influence on legitimate traffic. Simulations, which were then performed with the open source controller Ryu, show that our approach is effective in alleviating DDoS attacks and quarantining the attackers by numerable remapping process. The simulations also demonstrate that our dynamic defense imposes little effect on legitimate users, and the overhead introduced by remapping procedure is acceptable.

• 시스템엔지니어링학술지
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• 제12권2호
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• pp.101-114
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• 2016

A model-based systems engineering (MBSE) approach to implementing hardware-based network cybersecurity controls for APR1400 non-safety data network is presented in this work. The proposed design was developed by implementing packet filtering and deep packet inspection functions to control the unauthorized traffic and malicious contents. Denial-of-Service (DoS) attack was considered as a potential cybersecurity issue that may threaten the data availability and integrity of DCS gateway servers. Logical design architecture was developed to simulate the behavior of functions flow. HDL-based physical architecture was modelled and simulated using Xilinx ISE software to verify the design functionality. For effective modelling process, enhanced function flow block diagrams (EFFBDs) and schematic design based on FPGA technology were together developed and simulated to verify the performance and functional requirements of network security controls. Both logical and physical design architectures verified that hardware-based cybersecurity controls are capable to maintain the data availability and integrity. Further works focus on implementing the schematic design to an FPGA platform to accomplish the design verification and validation processes.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 춘계학술대회
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• pp.639-642
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• 2015

MANET(Mobile Ad-Hoc Network)의 라우팅 기능에 대한 공격인 홀 공격은 네트워크 전송성능에 중요한 영향을 미친다. MANET은 단말기만으로 구성되는 임시 네트워크로 악성공격에 대한 대응이 쉽지 않아 홀 공격에 매우 취약하여 전송성능에 치명적인 영향을 받을 수 있다. 본 연구에서는 홀공격의 일종은 그레이홀 공격이 MANET의 전송 성능에 미치는 영향을 컴퓨터 시뮬레이션을 사용하여 분석하여 본다. 연구의 대상 트래픽으로는 음성 트래픽을 사용하였으며, 그레이홀 공격의 영향을 블랙홀 공격과 비교하여 본다. 본 연구의 방법과 결과는 MANET에서 악성공격에 대응하기 위한 자료로 활용될 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권7호
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• pp.2512-2531
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• 2014

We propose a new Distributed Denial of Service (DDoS) defense mechanism that protects http web servers from application-level DDoS attacks based on the two methodologies: whitelist-based admission control and busy period-based attack flow detection. The attack flow detection mechanism detects attach flows based on the symptom or stress at the server, since it is getting more difficult to identify bad flows only based on the incoming traffic patterns. The stress is measured by the time interval during which a given client makes the server busy, referred to as a client-induced server busy period (CSBP). We also need to protect the servers from a sudden surge of attack flows even before the malicious flows are identified by the attack flow detection mechanism. Thus, we use whitelist-based admission control mechanism additionally to control the load on the servers. We evaluate the performance of the proposed scheme via simulation and experiment. The simulation results show that our defense system can mitigate DDoS attacks effectively even under a large number of attack flows, on the order of thousands, and the experiment results show that our defense system deployed on a linux machine is sufficiently lightweight to handle packets arriving at a rate close to the link rate.

• 디지털산업정보학회논문지
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• 제10권1호
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• pp.105-112
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• 2014

The utilization of Wireless Ad Hoc Network which can build easily network using wireless device in difficult situation to build network is very good. However, it has security threat element because it transfers data by only forwarding of wireless devices. The measures against this should be prepared because damage by especially routing attack can affect the entire network. It is hard to distinguish malicious node and normal node among nodes composing network and it is not easy also to detect routing attack and respond to this. In this paper, we propose new method which detect routing attack and can respond to this. The amount of traffic in all nodes is measured periodically to judge the presence or absence of attack node on the path set. The technique that hides inspection packet to suspected node and transmits is used in order to detect accurately attack node in the path occurred attack. The experiment is performed by comparing SRAODA and SEAODV technique to evaluate performance of the proposed technique and the excellent performance can be confirmed.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.783-786
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• 2015

라우팅 정보에 대한 변화를 발생시켜 전송기능을 방해하는 홀 공격은 MANET(Mobile Ad-Hoc Network)과 같은 임시 통신망에 치명적인 결과를 초래한다. 홀 공격의 한 종류인 블랙홀 공격은 악성 노드인 블랙홀 노드가 라우팅 정보를 위조하여 네트워크 내에 전송되는 정보를 흡수함으로서 네트워크 성능을 마비시키는 악성공격의 일종이다. 블랙홀 공격이 MANET의 전송성능에 미치는 영향은 매우 크므로 다양한 네트워크 환경에 대해 블랙홀 공격이 미치는 전송성능을 분석하는 것은 매우 의미있는 일이다. 본 연구에서는 복수의 블랙홀 노드에서 발생된 블랙홀 공격이 MANET의 전송 성능에 미치는 영향을 분석해 본다. 분성 방법으로는 NS-2를 사용한 컴퓨터 시뮬레이션을 활용하며 분석대상 서비스로는 음성 트래픽을 사용한다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 춘계학술대회
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• pp.578-581
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• 2014

블랙홀 공격은 라우팅 기능에 대한 공격의 일종으로서 네트워크 전송성능에 치명적인 영향을 초래할 수 있다. 특히, 단말기만으로 구성되어 악성침해 대비 기능을 갖추기가 수월하지 않은 MANET(Mobile Ad-hoc Network)에서 블랙홀 공격이 시도될 경우 네트워크 전체의 전송기능이 매우 저하될 수 있다. 본 논문에서는 블랙홀 공격이 네트워크 전송성능에 미치는 영향을 격자구조 MANET을 대상으로 분석해 본다. 특히 블랙홀 공격이 발생되는 지점을 다양하게 설정하여 전송 성능을 측정하고 이를 랜덤구조 MANET의 전송결과와 비교하여 분석해본다. 본 논문은 컴퓨터 시뮬레이션을 사용하여 수행하며, 전송 대상 트래픽으로는 VoIP(Voice over Internet Protocol) 트래픽으로 한다. 본 연구의 결과는 MANET에서 블랙홀 공격에 대응하기 위한 자료로 사용될 수 있다.

• 인터넷정보학회논문지
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• 제20권2호
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• pp.9-19
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• 2019

인터넷을 통한 서비스 및 사용자가 급격하게 증가하고 있다. 이에 따라 사이버 공격도 증가하고 있으며, 정보 유출, 금전적 피해 등이 발생하고 있다. 정부, 공공기관, 회사 등은 이렇게 급격한 사이버 공격 중 알려진 악성코드에 대응하기 위하여 시그니처 기반의 탐지규칙을 이용한 보안 시스템을 사용하고 있지만, 시그니처 기반의 탐지규칙을 생성하고 검증하는 데 오랜 시간이 걸린다. 이런 문제를 해결하기 위하여 본 논문에서는 잠재 디리클레 할당 알고리즘을 통한 시그니처 추출과 트래픽 분석 기술 등을 이용하여 시그니처 기반의 탐지규칙 생성 및 검증 시스템을 제안하고 개발하였다. 개발한 시스템을 실험한 결과, 기존보다 훨씬 신속하고, 정확하게 탐지규칙을 생성하고 검증하였다.