• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.3
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• pp.691-705
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• 2012

Buffer overflow vulnerability is the most representative one that an attack method and its countermeasure is frequently developed and changed. This vulnerability is still one of the most critical threat since it was firstly introduced in middle of 1990s. Shellcode is a machine code which can be used in buffer overflow attack. Attackers make the shellcode for their own purposes and insert it into target host's memory space, then manipulate EIP(Extended Instruction Pointer) to intercept control flow of the target host system. Therefore, a lot of research to defend have been studied, and attackers also have done many research to bypass security measures designed for the shellcode defense. In this paper, we investigate shellcode defense and attack techniques briefly and we propose our new methodology which can hide shellcode in the 24bit BMP image. With this proposed technique, we can easily hide any shellcode executable and we can bypass the current detection and prevention techniques.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.3
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• pp.87-96
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• 2014

Hackers try to achieve their purpose in a variety of ways, such as operating own website and hacking a website. Hackers seize a large amount of private information after they have made a zombie PC by using malicious code to upload the website and it would be used another hacking. Almost detection technique is the use Snort rule. When unknown code and the patterns in IDS/IPS devices are matching on network, it detects unknown code as malicious code. However, if unknown code is not matching, unknown code would be normal and it would attack system. Hackers try to find patterns and make shellcode to avoid patterns. So, new method is needed to detect that kinds of shellcode. In this paper, we proposed a noble method to detect the shellcode by using Shannon's information entropy.

• Electronics and Telecommunications Trends
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• v.23 no.1 s.109
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• pp.145-152
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• 2008

공격자의 주요 목적은 원격 호스트의 제어 권한을 얻는 것이다. 이것은 공격자가 원격호스트의 컨트롤 플로를 변경시켜 악의적인 코드를 임의로 실행시킬 수 있는 취약한 서비스가 존재하기 때문에 가능하다. 공격자들이 원격 호스트의 제어 권한을 얻기 위한 일반적인 방법은 취약한 서비스를 대상으로 쉘코드(shellcode) 전송을 통해서이다. 네트워크 기반 최신의 공격 탐지 기술들이 점점 사용영역을 넓혀가면서 이를 회피하기 위해 쉘코드들도 진화를 계속하고 있으며, 최근 2~3년 전부터 폴리몰픽(polymorphism)과 메타몰픽(metamorphism) 기법의 사용이 활발해지고 있다. 본 고에서는 이중, 쉽게 이용할 수 있는 엔진들이 많이 알려져 있어 그 예상 피해가 심각하리라 생각되는 폴리몰픽 형태의 쉘코드가 가지는 특징 및 이를 탐지하기 위한 최신 기술들을 소개한다.

• International Journal of Computer Science & Network Security
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• v.21 no.12
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• pp.207-212
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• 2021

A buffer overflow attack is carried out to subvert privileged program functions to gain control of the program and thus control the host. Buffer overflow attacks should be prevented by risk managers by eradicating and detecting them before the software is utilized. While calculating the size, correct variables should be chosen by risk managers in situations where fixed-length buffers are being used to avoid placing excess data that leads to the creation of an overflow. Metamorphism can also be used as it is capable of protecting data by attaining a reasonable resistance level [1]. In addition, risk management teams should ensure they access the latest updates for their application server products that support the internet infrastructure and the recent bug reports [2]. Scanners that can detect buffer overflows' flaws in their custom web applications and server products should be used by risk management teams to scan their websites. This paper presents an experiment of buffer overflow vulnerability and attack. The aims to study of a buffer overflow mechanism, types, and countermeasures. In addition, to comprehend the current detection plus prevention approaches that can be executed to prevent future attacks or mitigate the impacts of similar attacks.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.4
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• pp.29-39
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• 2009

In order to respond against worms which are malicious programs automatically spreading across communication networks, worm detection approach by generating signatures resulting from analyzing worm-related packets is being mostly used. However, to avoid such signature-based detection techniques, usage of exploits employing mutated polymorphic types are becoming more prevalent. In this paper, we propose a novel static analysis approach for detecting the decryption routine of polymorphic exploit code, Our approach detects a code routine for performing the decryption of the encrypted original code which are contained with the polymorphic exploit code within the network flows. The experiment results show that our approach can detect polymorphic exploit codes in which the static analysis resistant techniques are used. It is also revealed that our approach is more efficient than the emulation-based approach in the processing performance.

• Journal of the Korea Society of Computer and Information
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• v.27 no.5
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• pp.149-156
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• 2022

Recently, there have been many reports of document-type malicious code injecting malicious code into Microsoft Office files. Document-type malicious code is often hidden by encoding the malicious code in the document. Therefore, document-type malware can easily bypass anti-virus programs. We found that malicious code was inserted into the Visual Basic for Applications (VBA) macro, a function supported by Microsoft Office. Malicious codes such as shellcodes that run external programs and URL-related codes that download files from external URLs were identified. We selected 354 keywords repeatedly appearing in malicious Microsoft Office files and defined the number of times each keyword appears in the body of the document as a feature. We performed machine learning with SVM, naïve Bayes, logistic regression, and random forest algorithms. As a result, each algorithm showed accuracies of 0.994, 0.659, 0.995, and 0.998, respectively.