• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.3
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• pp.519-529
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• 2019

Nowadays, intelligent Android malware applies anti-analysis techniques to hide malicious behaviors and make it difficult for anti-virus vendors to detect its presence. Malware can use background components to hide harmful operations, use activity-alias to get around with automation script, or wipe the logcat to avoid forensics. During our study, several static analysis tools can not extract these hidden components like main activity, and dynamic analysis tools also have problem with code coverage due to partial execution of android malware. In this paper, we design and implement a system to analyze intelligent malware that uses anti-analysis techniques to improve detection rate of evasive malware. It extracts the hidden components of malware, runs background components like service, and generates all the intent events defined in the app. We also implemented a real-time logging system that uses modified logcat to block deleting logs from malware. As a result, we improve detection rate from 70.9% to 89.6% comparing other container based dynamic analysis platform with proposed system.

• KIPS Transactions on Software and Data Engineering
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• v.10 no.10
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• pp.421-428
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• 2021

The High Efficiency Image File Format (HEIF) is an MPEG-developed image format that utilizes the video codec H.265 to store still screens in a single image format. The iPhone has been using HEIF since 2017, and Android devices such as the Galaxy S10 have also supported the format since 2019. The format can provide images with good compression rates, but it has a complex internal structure and lacks significant compatibility between devices and software, making it not popular to replace commonly used JPEG (or JPG) files. However, despite the fact that many devices are already using HEIF, digital forensics research regarding it is lacking. This means that we can be exposed to the risk of missing potential evidence due to insufficient understanding of the information contained inside the file during digital forensics investigations. Therefore, in this paper, we analyze the HEIF formatted photo file taken on the iPhone and the motion photo file taken on the Galaxy to find out the information and features contained inside the file. We also investigate whether or not the software we tested support HEIF and present the requirement of forensic tools to analyze HEIF.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.4
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• pp.777-785
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• 2016

IM(Instant Messenger) chatting service can carry user's various information including life style, geographical position, and psychology & crime history and thus forensic analysis on the IM service is desirable. But, forensic analysis for KakaoTalk's chatting service is not well studied yet. For this reason, we study KakaoTalk's forensic analysis focusing on chatting service. This paper first details a general method of IM forensics investigating the previous articles about IM forensics although there are not many articles. Second, we discuss methodologies for IM forensics wherein we present analysis of table structure and method for reconstruction of chatting message. These result in the basic element of forensic tools of KakaoTalk chatting message. Last, we compare artifacts of KakaoTalk with that of WhatsApp. We conclude that these applications are, at least, different in that table structures and the ways to reconstruct chatting messages are not same and therefore digital evidences or artifacts are not same and somewhat distinct.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.184-186
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• 2022

Recently, as interest in personal information protection has increased, various apps for personal information protection have emerged. These apps protect data in various formats, such as photos, videos, and documents containing personal information, using encryption and hide functions. These apps can have a positive effect on personal information protection, but in digital forensics, they act as anti-forensic because they can be difficult to analyze data during the investigation process. In this paper, finds out PIN, an access control function, through reverse engineering on Calculator - photo vault, one of the personal information protection apps, and files such as photos and documents to which encryption and hide were applied. In addition, the vulnerability to this app was analyzed by research decryption for database files where logs for encrypted and hide files are stored.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.1
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• pp.31-42
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• 2017

Thumbnail, the small sized graphic file such as JPEG or GIF, serves to help the users to be recognized as a rapidly helps to make it easier recognize while browsing the large sized graphic file. Gallery application, which is installed in a later version of the 4.4.x(Kitkat) Android smartphone records the generated time of graphic file in thumbnail metadata. Thumbnail can be used to draw up the timeline of user action about user's action such as creation, modification, deletion with original graphic file analysis. Also, take advantage of the features thumbnails are stored sequentially in a single thumbcache file, even if the thumbcache is deleted, we can restore the thumbnails. This paper illustrates the feature of thumbnail created by Android OS basic gallery app and methods for utilization in digital forensics.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06a
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• pp.48-50
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• 2012

최근 안드로이드 스마트폰 애플리케이션(Application, 이하 앱) 개발자가 늘고 있지만 앱 저작권 보호 기술적인 제도가 미비하여 불법 복제 앱 사용량이 늘고 있는 추세이다. 본 논문에서는 포렌식 마크 기반 저작권 보호 기법에 대한 연구를 바탕으로 개발자에게 제공가능 한 셀프 체킹 라이브러리를 구현하였다. 그리고 셀프 체킹 라이브러리 구동성을 실험하기 위해 현존하는 앱 마켓 서버와 마켓 앱을 구축하여 실제 환경에서의 적용성 및 실용 가능성을 증명하였다. 현재 본 논문에서 제안한 기법이 실용화가 된다면 앱 저작권 보호 뿐만 아니라 스마트폰 앱 시장 발전에 크게 이바지 할 것이다.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.710-713
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• 2015

21세기 모바일 디바이스의 급속한 확산과 클라우드 컴퓨팅의 발전은 개인정보의 흐름을 개인용 컴퓨터에서 모바일 디바이스로 이동시켰다. 이에 따라 포렌식에서도 모바일 디바이스의 디지털 데이터를 중요한 증거로 인식하고 이에 대한 연구가 활발하게 진행 중이다. 하지만 클라우드 환경에서는 일반적으로 클라우드라고 인식되는 외부에 데이터를 저장하기 때문에 사용자 측의 디바이스에서는 디지털 증거의 획득이 쉽지 않다. 본 논문에서는 일반 사용자에게 클라우드 서비스로 대표되는 N드라이브, 다음 클라우드와 같은 클라우드 스토리지 서비스를 안드로이드 환경에서 이용해 보고 디바이스 내부에 생성되는 정보 중 디지털 포렌식의 관점에서 활용 가능한 정보를 수집 및 분석해보려 한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.5
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• pp.1107-1115
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• 2017

The most commonly used PKZIP format is a ZIP file, as well as a file format used in MS Office files and application files for Android smartphones. PKZIP format files, which are widely used in various areas, require structural analysis from the viewpoint of digital forensics and should be able to recover when files are damaged. However, previous studies have focused only on recovering data or extracting meaningful data using the Deflate compression algorithm used in ZIP files. Although most of the data resides in compressed data in the ZIP file, there is also forensically meaningful data in the rest of the ZIP file, so you need to restore it to a normal ZIP file format. Therefore, this paper presents a technique to recover a damaged ZIP file to a normal ZIP file when given.