• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.6
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• pp.43-51
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• 2010

It is meaningful to investigate data in unallocated space because we can investigate the deleted data. Consecutively complete file recovery using the File Carving is possible in unallocated area, but noncontiguous or incomplete data recovery is impossible. Typically, the analysis of the data fragments are needed because they should contain large amounts of information. Microsoft Word, Excel, PowerPoint and PDF document file's text are stored using compression or specific document format. If the part of aforementioned document file was stored in unallocated data fragment, text extraction is possible using specific document format. In this paper, we suggest the method of extracting a particular document file text in unallocated data fragment.

• Journal of Communications and Networks
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• v.17 no.5
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• pp.525-533
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• 2015

MS Office suit software is the most widely used electronic documents by a large number of users in the world, which has absolute predominance in office software market. MS Office 2007-2013 documents, which use new office open extensible markup language (OOXML) format, could be illegally used as cover mediums to transmit secret information by offenders, because they do not easily arouse others suspicion. This paper proposes nine forensic methods and an integrated forensic tool for OOXML format documents on the basis of researching the potential information hiding methods. The proposed forensic methods and tool cover three categories; document structure, document content, and document format. The aim is to prevent covert communication and provide security detection technology for electronic documents downloaded by users. The proposed methods can prevent the damage of secret information embedded by offenders. Extensive experiments based on real data set demonstrate the effectiveness of the proposed methods.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.2
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• pp.319-325
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• 2014

Since smart phones or tablet PCs have been widely used recently, the users can create and edit documents anywhere in real time. If the input and edit flows of documents can be traced, it can be used as evidence in digital forensic investigation. The typical document application is the MS(Microsoft) Office. As the MS Office applications consist of two file formats that Compound Document File Format which had been used from version 97 to 2003 and OOXML(Office Open XML) File Format which has been used from version 2007 to now. The studies on MS Office files were for making a decision whether the file has been tampered or not through detection of concealed items or analysis of documents properties so far. This paper analyzed the input order of text cells on MS Excel files and shows how to figure out what cell is the last edited in digital forensic perspective.

• International journal of advanced smart convergence
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• v.8 no.4
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• pp.47-57
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• 2019

We examine the weaknesses of the existing OOXML-based MS-Word file structure, and analyze how data concealment and forgery are performed in MS-Word digital documents. In case of forgery by including hidden information in MS-Word digital document, there is no difference in opening the file with the MS-Word Processor. However, the computer system may be malfunctioned by malware or shell code hidden in the digital document. If a malicious image file or ZIP file is hidden in the document by using the structural vulnerability of the MS-Word document, it may be infected by ransomware that encrypts the entire file on the disk even if the MS-Word file is normally executed. Therefore, it is necessary to analyze forgery and alteration of digital document through internal structure analysis of MS-Word file. In this paper, we designed and implemented a mechanism to detect this efficiently and automatic detection software, and presented a method to proactively respond to attacks such as ransomware exploiting MS-Word security vulnerabilities.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.3
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• pp.165-176
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• 2011

In this paper, we examine the reliability verification procedure of evidence analysis tools for computer forensics and test the famous tools for their functional requirements using the verification items proposed by standard document, TIAK.KO-12.0112. Also, we carry out performance evaluation based on test results and suggest the way of performance improvement for evidence analysis tools. To achieve this, we first investigate functions that test subjects can perform, and then we set up a specific test plan and create evidence image files which contain the contents of a verification items. We finally verify and analyze the test results. In this process, we can discover some weaknesses of most of analysis tools, such as the restoration for deleted & fragmented files, the identification of the file format which is widely used in the country and the processing of the strings composed of Korean alphabet.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.6
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• pp.1439-1448
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• 2018

Many electronic document files, including Microsoft Office Word (MS Word), have become a major issue in various legal disputes such as privacy, contract forgery, and trade secret leakage. The internal metadata of OOXML (Office Open XML) format, which is used since MS Word 2007, stores the unique Revision Identifier (RSID). The RSID is a distinct value assigned to a corresponding word, sentence, or paragraph that has been created/modified/deleted after a document is saved. Also, document history, such as addition/correction/deletion of contents or the order of creation, can be tracked using the RSID. In this paper, we propose a methodology to investigate discrimination between the original document and copy as well as possible document file leakage by utilizing the changes of the RSID according to the user's behavior.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.4
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• pp.9-13
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• 2021

With the development of communication technology, various forms of digital crime are increasing, and the need for digital forensics is increasing. Moreover, if a textual document containing sensitive data is deliberately deleted or modified by a particular person, it could be important data to prove its connection to a particular person and crime through a system that checks for data modification detection. This paper proposes a data modification detection system that can analyze the hash data, file size, file creation date, file modification date, file access date, etc. of SHA-256, one of the encryption techniques, focusing on text files, to compare whether the target text file is modified or not.

• Journal of Digital Forensics
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• v.12 no.3
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• pp.71-82
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• 2018

Using small cameras such as smartphones, criminals shoot secretly in public restrooms and women's changing rooms. And Revenge porn is also increasing. As a result social damage is increasing. Tumblr is an overseas service and it is very difficult to work with Tumbler on international legal cooperation and deletions. Thus In order to block the distribution of videos, victims must find and report the video URL themselves. But it's hard for victims who lack IT expertise to proceed those procedure. In this study, we automatically collect the URL of stored information and hash values of the images from API permlink of Tumbler blog. It is then saved as a document file with and presented to the victim. Through these technical methods, we can help victims report violations easily and quickly.

• The KIPS Transactions:PartC
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• v.19C no.4
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• pp.215-224
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• 2012

Today, individuals and businesses are a lot of paperwork through a computer. So many documents files are creating to digital type. And the digital type files are copied, moved by various media such as USB, E-mail and so on. A careful analysis of these digital materials can be tracked that occurred during the document editing work history. About these research are on the compound document file format, but has not been studied about the new OOXML format that how to analyze linkages between different document files, tracking an internal order, finding unsaved file for identify the process of creating the file. Future, the use of OOXML format digital documents will further increase, these document work history traceability in digital forensic investigation would be a big help. Therefore, this paper on the new OOXML format(has a forensic viewpoint) will show you how to track the internal order and analyze linkages between the files.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.3
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• pp.489-499
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• 2017

MS office is a office software which is widely used in the world. The OOXML format has been applied to the document structure from MS office 2007 to the newest version. In this regard, the method of data concealing, which is a representative anti-forensic act has been researched and developed, so the method of detecting concealed data is very important to the digital forensic investigation. In this paper, we present an improved data concealing method bypassing the previewers detecting methods for OOXML formatted MS office documents. In addition, we show concealment of the internal data like sheets and slides for MS office 2013 Excel and PowerPoint, and suggest an improved detecting algorithm against this data concealing.