• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.6
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• pp.1043-1053
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• 2023

Malware analysts work diligently to analyze and counteract malware, while developers persistently devise evasion tactics, notably through packing and obfuscation techniques. Although previous works have proposed general unpacking approaches, they inadequately address techniques like OEP obfuscation and API obfuscation employed by modern packers, leading to occasional failures during the unpacking process. This paper examines the OEP and API obfuscation techniques utilized by various packers and introduces a system designed to automatically de-obfuscate them. The system analyzes the memory of packed programs, detects trampoline codes, and identifies obfuscated information, for program reconstruction. Experimental results demonstrate the effectiveness of our system in de-obfuscating programs that have undergone OEP and API obfuscation techniques.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.4
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• pp.709-720
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• 2013

Virtualization obfuscation makes hard to analyze the code by applying virtualization to code section. Protected code by common used virtualization obfuscation technique has become known that it doesn't have restored point and also it is hard to analyze. However, it is abused to protect malware recently. So, It is been hard to analyze and take action for malware. Therefore, this paper's purpose is analyze and take action for protected malware by virtualization obfuscation technique through implement tool which can extract virtualization structure automatically and trace execution process. Hence, basic structure and operation process of virtualization obfuscation technique will be handled and analysis result of protected malware by virtualization obfuscation utilized Equation Reasoning System, one kind of program analysis. Also, we implement automatic analysis tool, extract virtualization structure from protected executable file by virtualization obfuscation technique and deduct program's execution sequence.

• 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.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.3
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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.

• Journal of Korea Multimedia Society
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• v.15 no.1
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• pp.1-8
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• 2012

In this paper, we propose the digital video frame obfuscation method for intellectual property protection using the DC component of the intra frame and the motion vector of the inter frame at digital video encoding. The proposed method considers characteristics of the HVS (human visual system) which is sensitive at the low frequency and the middle frequency. This method makes the signal distorted as operating XOR between authentication signal and the DC coefficient of the intra frame including main information and the sign of the motion vector including edge motion, so that the video is normally displayed only when suitable authentication signal is applied.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.3
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• pp.17-28
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• 2006

The appearance of variant malicious codes using obfuscation techniques is accelerating the spread of malicious codes around the detection by a vaccine. n a system does not patch detection patterns for vulnerabilities and worms to the vaccine, it can be infected by the worms and malicious codes can be spreaded rapidly to other systems and networks in a few minute. Moreover, It is limited to the conventional pattern based detection and treatment for variants or new malicious codes. In this paper, we propose a method of behavior based detection by the static analysis, the dynamic analysis and the dynamic monitoring to detect a malicious code using obfuscation techniques with the PE compression. Also we show that dynamic monitoring can detect worms with the PE compression which accesses to important resources such as a registry, a cpu, a memory and files with the proposed method for similarity.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.3
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• pp.493-501
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• 2020

For the obfuscation of Flow Analysis on the Android operating system, the size of the Flow Graph can be large enough to make analysis difficult. To this end, a library in the form of aar was implemented so that it could be inserted into the application in the form of an external library. The library is designed to have up to five child nodes from the entry point in the dummy code, and for each depth has 2n+1 numbers of methods from 100 to 900 for each node, so it consists of a total of 2,500 entry points. In addition, entry points consist of a total of 150 views in XML, each of which is connected via asynchronous interface. Thus, the process of creating a Inter-procedural Control Flow Graph has a maximum of 14,175E+11 additional cases. As a result of applying this to application, the Inter Procedure Control Flow Analysis too generates an average of 10,931 edges and 3,015 nodes with an average graph size increase of 36.64%. In addition, in the APK analyzing process showed that up to average 76.33MB of overhead, but only 0.88MB of execution overhead in the user's ART environment.

• Journal of Korea Society of Digital Industry and Information Management
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• v.13 no.2
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• pp.1-11
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• 2017

In this paper, we design and implement PADIL(Prediction And Detection of Information Leakage) system that predicts and detect information leakage behavior of insider by analyzing network traffic and applying a variety of machine learning methods. we defined the five-level information leakage model(Reconnaissance, Scanning, Access and Escalation, Exfiltration, Obfuscation) by referring to the cyber kill-chain model. In order to perform the machine learning for detecting information leakage, PADIL system extracts various features by analyzing the network traffic and extracts the behavioral features by comparing it with the personal profile information and extracts information leakage level features. We tested various machine learning methods and as a result, the DecisionTree algorithm showed excellent performance in information leakage detection and we showed that performance can be further improved by fine feature selection.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.960-965
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• 2006

Privacy and security are latent problems in pervasive healthcare system. For the sake of protecting health monitoring information, it is necessary to classify and categorize the various contexts in terms of obfuscation. In this paper, we propose the physiological context categorization and specification methodology by exploiting data fusion network for automatic context alignment. In addition, we introduce the methodologies for making various level of physiological context on the context aware application model, which is wear-UCAM. This physiological context has several layers of context according to the level of abstraction such as user-friendly level or parametric level. This mechanism facilitates a user to restrict access to his/her monitoring results based on the level of details in context.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.01a
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• pp.119-122
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• 2019

최근 웹 변조 공격은 대형 포탈, 은행, 학교 등 접속자가 많은 홈페이지에 악성 URL을 불법 삽입하여 해당 URL을 통해 접속자 PC에 자동으로 악성코드 유포하고 대규모 봇넷(botnet)을 형성한 후 DDoS 공격을 수행하거나 감염 PC들의 정보를 지속적으로 유출하는 형태로 수행된다. 이때, 홈페이지에 삽입되는 악성 URL은 탐지가 어렵도록 Javascript 난독화 기법(obfuscation technique) 등으로 은밀히 삽입된다. 본 논문에서는 웹 소스코드에 은닉된 악성 Javascript URL들에 대한 일괄 점검체계를 제안하며, 구현된 점검체계의 prototype을 활용하여 점검성능에 대한 시험결과를 제시한다.