SLAMorris Final Thesis After Corrections.pdf - Cranfield University

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<strong>Final</strong>ly I’d like to thank my wonderful partner Gavin for putting up with me through the highs and lows. iv
TABLE OF CONTENTS ABSTRACT ......................................................................................................... i ACKNOWLEDGEMENTS................................................................................... iii LIST OF FIGURES ............................................................................................. xi LIST OF TABLES ............................................................................................. xiii 1 Introduction ...................................................................................................... 1 1.1 Introduction .......................................................................................... 1 1.2 Justification .......................................................................................... 2 1.3 Aim ....................................................................................................... 3 1.4 Hypothesis ........................................................................................... 3 1.5 Methodology ........................................................................................ 4 1.6 <strong>Thesis</strong> Outline ...................................................................................... 5 1.7 Contributions ........................................................................................ 9 2 Related Research .......................................................................................... 11 2.1 Introduction ............................................................................................. 11 2.2 Forensic Computing ................................................................................ 11 2.2.1 Methodologies .................................................................................. 14 2.2.2 Tools used in Forensic Computing ................................................... 17 2.2.3 Current Opportunities ....................................................................... 20 2.3 Data and information ............................................................................... 22 2.3.1 Storing information ........................................................................... 22 2.3.2 Metadata .......................................................................................... 25 2.3.3 Event Reconstruction ....................................................................... 27 2.3.4 Corrupting data ................................................................................ 30 2.4 Thumbnails and the Thumbnail Cache ................................................... 32 2.4.1 Visual thumbnails and their applications in computing ..................... 33 2.4.2 Operating system Thumbnail Caches .............................................. 34 2.4.3 Forensic significance ........................................................................ 36 2.5 Conclusion .............................................................................................. 38 3 Research Objectives, Considerations and Tools. .......................................... 41 3.1 Introduction ............................................................................................. 41 3.2 Objectives ............................................................................................... 41 3.3 Potential Considerations ......................................................................... 43 3.4 Tools ....................................................................................................... 44 3.5 Conclusion .............................................................................................. 45 4 Defining Evidential Value............................................................................... 47 4.1 Introduction ............................................................................................. 47 4.2 Evidential Constraints ............................................................................. 47 4.2.1 Legal Constraints ............................................................................. 48 4.2.2 Evidential Constraints ....................................................................... 50 4.2.3 Reliability Constraints ....................................................................... 51 v
Page 1: CRANFIELD UNIVERSITY SARAH LOUISE A
Page 5 and 6: ABSTRACT This thesis establishes th
Page 7: ACKNOWLEDGEMENTS “And above all,
Page 11 and 12: 6 The structure and behaviour of th
Page 13 and 14: 8.6.1 Stage 1: Preliminary Checks .
Page 15 and 16: LIST OF FIGURES Figure 1-1:A breakd
Page 17 and 18: LIST OF TABLES Table 5-1: A summary
Page 21 and 22: 1 Introduction 1.1 Introduction In
Page 23 and 24: potential difficulty is the identif
Page 25 and 26: This is followed by a structural an
Page 27 and 28: Chapter 6 describes the structure a
Page 29 and 30: Chapter 11 evaluates the methodolog
Page 31 and 32: 2 Related Research 2.1 Introduction
Page 33 and 34: Generally individuals, including so
Page 35 and 36: thought to be a disciplinary offenc
Page 37 and 38: 2.2.2 Tools used in Forensic Comput
Page 39 and 40: structure and behaviour. Winhex pro
Page 41 and 42: with it are important aspects of an
Page 43 and 44: An important question for each arte
Page 45 and 46: For this research it is necessary t
Page 47 and 48: 2007], which assist in building eve
Page 49 and 50: and therefore he did not have priva
Page 51 and 52: data may be affected by the behavio
Page 53 and 54: thumbnail cache is implemented in f
Page 55 and 56: available for office documents; the
Page 57 and 58: future. It is possible to establish
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structure and syntax the user and s
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Identify existing file carving tech
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throughout this research. Within th
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corroborate the results. Time const
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4.2.1 Legal Constraints The law can
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to the evidence and to ensure any a
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To ensure the evidence is accurate
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evidence being extracted is crucial
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analyse human behaviour, it can sti
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4.3 Criteria for evaluating the evi
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In order to determine an artefact w
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5 The Structure and Behaviour of th
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the way data changes. The experimen
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5.4 Default Installations This sect
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Figure 5-3: The structure of thumbn
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these can be identified by the addi
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The tEXt chunks contain the metadat
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holds information about sample dept
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Start of tEXt Chunk This tEXt chunk
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00 00 00 2074 45 58 7453 6F 66 74 @
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order to establish if the software
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Each piece of software installed by
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which is present in the subrecords
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5.6.2 The modification of subrecord
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ascertain if unused subrecords woul
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in thumbnail view. This shows that
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5.9.1 Metadata There are three dist
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only information which does not con
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information in the .thumbnails cach
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uses substantially more checks whic
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any manipulation to appear as stand
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highlighting the need for understan
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elationship between information con
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document the state of a default Win
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Figure 6-1: Directory structure for
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Clone 1-8: Directories at level 0 w
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Figure 6-2: The centralised thumbna
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Start of Record 87 F7 6A 62 4B 7B C
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Start of standard thumbnail cache s
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Start of subrecord 14F8CE010 43 4D
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6.5 Identifying the behaviour The t
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greater than the maximum size image
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experiment was repeated with a non-
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to be shown [Douglas, 2009].Figure
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6.5.1.2 Circumstances where informa
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thumbnail cache based solely upon t
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the cache to remove inactive record
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6.6.1 Windows.edb The database for
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Figure 6-10: Identifying the Defaul
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thumbnail view for 30 seconds. Upon
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checks are performed on the associa
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showing a relationship between info
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The type of a file can be identifie
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The event timeline created could th
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6.9.2 Media thumbnails In Windows 7
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the provenance of artefacts. This i
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6.10.2 Interpretation of Results An
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however it is still possible to tam
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implementations of the thumbnail ca
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valid results only when the file is
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7.3.1 Statistical Methods If docume
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ate for HTML and JPEG files [Veenma
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Having described current methods fo
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previous experiments or downloaded
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L2: The fragment is part of a visua
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Table 7-1: Breakdown of file fragme
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approximately half the data in Data
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Table 7-3: A list of thumbnail cach
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Figure 7-2: Classifications for thu
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7.7.2 H2 For the identification of
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Relative offset: 48 0B 09 0C 11 0F
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The Bayesian Network takes into acc
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Figure 7-3: Bayesian network for H1
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Actual Fragment Type(Percentage) 7.
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Actual Fragment Type(Percentage) Ta
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Table 7-19: Method 4 Results for th
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more suited to pattern recognition
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and 2. This is possible because the
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This chapter has successfully ident
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8.2 Problem Definition In the intro
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information to examine at the end o
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files is described on the Joint Pho
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were not from thumbnail cache files
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In order to identify potential H3 f
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Actual Fragment Type (Percentage) p
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Figure 8-3: A summary of the hybrid
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cache file fragments. The headers i
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follow the standard PNG specificati
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then be viewed by an analyst and us
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Actual Fragment Type (Percentage) T
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8.8 Discussion The end aim of Chapt
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identification method into stages l
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9 Thumbnail cache fragment reassemb
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Once the fragments have been identi
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9.3.2 Logging In order to maintain
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H1:Thumbcache_idx.db file H2: Image
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Therefore this research assumes tha
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ecords and 2 partial records. The n
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equirement for generating table siz
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100% success rate, with 0% false po
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then stored and marked as a complet
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Once a start of file fragment has b
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number of fragments which contain o
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Figure 9-7: Reassembling an image b
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As the number of fragments being an
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file fragment identification on sto
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Linux Category_4: The last fragment
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Table 9-1: Results from reassembly
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activity. All the non-standard subr
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which substantially reduces the inf
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10 Establishing the evidential valu
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The thumbnail cache artefact extrac
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and 6. Each stage of the method has
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adapted to extract artefact from ot
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10.7 Discussion Both live system an
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10.8 Conclusion This chapter evalua
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Figure 11-1: A breakdown of aim of
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analysing the file type it is possi
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singular file fragment; by combinin
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processing time of the reassembly m
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In Chapter 9.5 a decision was taken
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12 Conclusions and future work 12.1
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potential for improving the identif
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installations of the operating syst
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Carnagey, N.L., Anderson, C.A. & Bu
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Facebook, 2013. Facebook. Available
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Helix, 2011. Helix. Available at: h
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Noblett, M., Pollitt, M., Presley,
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Stone-kaplan, K., Roter, M., 2003.
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APPENDICES Cranfield University | 3
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A.1.3 Image File Header typedefstru
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Appendix B Bayesian probability tab
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B.8 Fragment contains the ASCII str
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B.15 32 byte record structure SR po
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B.19 H3 Each byte frequency is less
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B.21 H5 Stored in valid PNG chunks
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Appendix C Peer Reviewed Publicatio
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Cranfield University | 327
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SLAMorris Final Thesis After Corrections.pdf - Cranfield University

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