• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.3
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• pp.1210-1230
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• 2015

Android is the world's most utilized smartphone OS which consequently, also makes it an attractive target for attackers. The most representative method of hacking used against Android apps is known as repackaging. This attack method requires extensive knowledge about reverse engineering in order to modify and insert malicious codes into the original app. However, there exists an easier way which circumvents the limiting obstacle of the reverse engineering. We have discovered a method of exploiting the Android code-signing process in order to mount a malware as an example. We also propose a countermeasure to prevent this attack. In addition, as a proof-of-concept, we tested a malicious code based on our attack technique on a sample app and improved the java libraries related to code-signing/verification reflecting our countermeasure.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.4
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• pp.757-766
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• 2013

The Malicious code that targets Android is growing dramatically as the number of Android users are increasing. Most of the malicious code have an intention of leaking personal information. Recently in Korea, a malicious code 'chest' has appeared and generated monetary damages by using malicious code to leak personal information and try to make small purchases. A variety of techniques to detect personal information leaks have been proposed on Android platform. However, the existing techniques are hard to apply to the user's smart-phone due to the characteristics of Android security model. This paper proposed a technique that detects and blocks file approaches and internet connections that are not allowed access to personal information by using the system call hooking in the kernel and white-list based approach policy. In addition, this paper proved the possibility of a real application on smart-phone through the implementation.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.4
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• pp.220-231
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• 2002

Trojan-horse programs are the programs that disguise normal and useful programs but do malicious thing to the hosts. This paper proposes an anti-Trojan horse mechanism using the information attached to the code by the developers. In this mechanism, each code is accompanied with the information on their possible accesses to resources, and based on this information users determine whether the code is malicious or not. Even in the case a code is accepted by users due to its non-malicious appearance, its runtime behaviors are monitored and halted whenever any attempts to malicious operations are detected. By hiring such runtime monitoring system, this mechanism enables detecting unknown Trojan horses and reduces the decision-making overhead being compared to the previous monitoring-based approaches. We describe the mechanism in a formal way to show the advantages and the limitations of the security this mechanism provides.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.3
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• pp.579-589
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• 2017

The cloud environment is hypervisor-based, and many virtual machines are interconnected, which makes propagation of malicious code easier than other environments. Accordingly, this paper proposes a malicious traffic dynamic analysis system for secure cloud environment. The proposed system continuously monitors and analyzes malicious activity in an isolated virtual network environment by distinguishing malicious traffic that occurs in a cloud environment. In addition, the analyzed results are reflected in the distinguishment and analysis of malicious traffic that occurs in the future. The goal of this research is secure and efficient malicious traffic dynamic analysis by constructing the malicious traffic analysis environment in the cloud environment for detecting and responding to the new and variant malicious traffic generated in the cloud environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7C
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• pp.743-750
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• 2003

With the expansion of computer technology the mobility of a mobile agent code having the flexibility in the dispersive computer situation is used to set up the applications distributed on the Internet. As it also has the ability to transmit the mobile code of a mobile agent and to receive it from a far-off host, the executive circumstances of the host system in which an agent is executed have to access to an agent code and the executive state capable of executing an agent code. Therefore, it is difficult to prevent the forgery, the alteration and the wrong execution of an agent from a malicious host. This dissertation suggests the mechanism which can protect an agent from the malicious action through the executive pursuit of a code-named mobile agent. The security of this mechanism is verified through the protective process of a mobile agent in this mechanism.

• Journal of Convergence Society for SMB
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• v.5 no.4
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• pp.37-42
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• 2015

Due to the advance of ICT, a variety of attacks have been developing and active. Recently, APT attacks using malicious codes have frequently occurred. Advanced Persistent Threat means that a hacker makes different security threats to attack a certain network of a company or an organization. Exploiting malicious codes or weaknesses, the hacker occupies an insider's PC of the company or the organization and accesses a server or a database through the PC to collect secrets or to destroy them. The paper suggested a countermeasure to cope with APT attacks through an APT attack process. It sought a countermeasure to delay the time to attack taken by the hacker and suggested the countermeasure able to detect and remove APT attacks.

• Convergence Security Journal
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• v.8 no.4
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• pp.1-8
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• 2008

Not only the recent hacking techniques are becoming more malicious with the sophisticated technology but also its consequences are bringing more damages as the broadband Internet is growing rapidly. These may include invasion of information leakage, or identity theft over the internet. Its intent is very destructive which can result in invasion of information leakage, hacking, one of the most disturbing problems on the net. This thesis describes the technology of how you can effectively analyze and detect these kind of E-Mail malicious codes. This research explains how we can cope with malicious code more efficiently by detection method.

• Journal of the Korea Society of Computer and Information
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• v.23 no.11
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• pp.85-93
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• 2018

In recent years, there has been an increasing number of ways to distribute document-based malicious code using vulnerabilities in document files. Because document type malware is not an executable file itself, it is easy to bypass existing security programs, so research on a model to detect it is necessary. In this study, we extract main features from the document structure and the JavaScript contained in the stream object In addition, when JavaScript is inserted, keywords with high occurrence frequency in malicious code such as function name, reserved word and the readable string in the script are extracted. Then, we generate a machine learning model that can distinguish between normal and malicious. In order to make it difficult to bypass, we try to achieve good performance in a black box type algorithm. For an experiment, a large amount of documents compared to previous studies is analyzed. Experimental results show 98.9% detection rate from three different type algorithms. SVM, which is a black box type algorithm and makes obfuscation difficult, shows much higher performance than in previous studies.

• Journal of the Korea Society of Computer and Information
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• v.14 no.9
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• pp.47-54
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• 2009

Malicious codes, which are spread through WWW are now evolved with various hacking technologies However, detecting technologies for them are seemingly not able to keep up with the improvement of hacking and newly generated malicious codes. In this paper, we define the requirements of detecting systems based on the analysis of malicious codes and their spreading characteristics, and propose an improved detection scheme which monitors HTTP Outbound traffic and detects spreading malicious codes in real time. Our proposed scheme sets up signatures in IDS with confirmed HTML tags and Java scripts which spread malicious codes. Through the verification analysis under the real-attacked environment, we show that our scheme is superior to the existing schemes in satisfying the defined requirements and has a higher detection rate for malicious codes.

• Convergence Security Journal
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• v.6 no.2
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• pp.21-29
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• 2006

Recently, illegal manipulation and forgery threats on computer softwares are increasing. Specially, forge the code of program and disrupt normal operation using a malicious loader program against the Internet application client. In this paper, we first analyze and generate signatures of malicious loader detection. And, we propose a method to secure the application client based on profiling which can detect and filter out abnormal malicious loader requests.