Difference between pages "Windows Prefetch File Format" and "GRR"

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(Section C)
 
(Publications)
 
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{{Infobox_Software |
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  name = Rekall |
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  maintainer = [[Darren Bilby]] and others |
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  os = {{Cross-platform}} |
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  genre = {{Incident response}} |
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  license = {{APL}} |
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  website = [https://code.google.com/p/grr/ code.google.com/p/grr/] |
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}}
  
A Windows Prefetch file consists of one file header and multiple file sections with different content. Not all content has an obvious forensic value.
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GRR is an Incident Response Framework focused on Remote Live Forensics.
  
As far as have been possible to ascertain, there is no public description of the format. The description below has been synthesised from examination
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= See also =
of multiple prefetch files.
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* [[rekall]]
  
== Characteristics ==
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= External Links =
Integer values are stored in little-endian.
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* [https://code.google.com/p/grr/ Project site]
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* [https://code.google.com/p/grr/wiki/ProjectFAQ Project FAQ]
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* [http://grr.googlecode.com/git/docs/index.html Documentation]
  
Strings are stored as UTF-16 little-endian without a byte-order-mark (BOM).
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== Publications ==
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* [http://static.googleusercontent.com/media/research.google.com/en/us/pubs/archive/37237.pdf Distributed forensics and incident response in the enterprise], by [[Michael Cohen]], [[Darren Bilby]], G. Caronni. Digital Investigation, 2011.
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* [https://googledrive.com/host/0B9hc84IflFGbN2IwMTUyYTUtMTU0Mi00ZWQ3LWFhNDktM2IyMTg5MmY3OWI0/Hunting%20in%20the%20Enterprise:%20Forensic%20Triage%20and%20Incident%20Response Hunting in the enterprise: Forensic triage and incident response], by [[Andreas Moser], [[Michael Cohen]], Digital Investigation, 2013.
  
Timestamps are stored as Windows Filetime in UTC.
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== Presentations ==
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* [https://googledrive.com/host/0B1wsLqFoT7i2N3hveC1lSEpHUnM/Docs/GRR%20Rapid%20Response%20-%20OSFC%202012.pdf OSDFC 2012 GRR Overview], by [[Darren Bilby]]
  
== Header ==
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== Workshops ==
 
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* [https://drive.google.com/?usp=chrome_app#folders/0B1wsLqFoT7i2eU1jU0JldW9JUU0 OSDFC workshop 2013] , by [[Darren Bilby]]
This format has been observed on Windows XP, ...  will need to be modified for Vista/Win7 format
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{| class="wikitable"
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|-
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! Field
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! Offset
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! Length
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! Type
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! Notes
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|-
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| H1
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| 0x0000
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| 4
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| DWORD
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| Format version (see format version section below)
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|-
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| H2
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| 0x0004
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| 4
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| DWORD
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| Signature 'SCCA' (or in hexadecimal representation 0x53 0x43 0x43 0x4)
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|-
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| H3
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| 0x0008
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| 4
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| DWORD?
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| Unknown - Values observed: 0x0F - Windows XP, 0x11 - Windows 7, Windows 8.1
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|-
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| H4
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| 0x000C
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| 4
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| DWORD
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| Prefetch file length.
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|-
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| H5
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|0x0010
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| 60
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| USTR
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| Name of executable as Unicode string, truncated after 29 characters, if necessary, and terminated by an end-of-string character (U+0000). As it appears in the prefetch file file name.
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|-
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| H6
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|0x004C
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|4
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|DWORD
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|The prefetch hash, as it appears in the prefetch file name.
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|-
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| H7
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|0x0050
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|4
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|?
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| Unknown (flags)? Values observed: 0 for almost all prefetch files (XP); 1 for NTOSBOOT-B00DFAAD.pf (XP)
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|-
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|}
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The following part of the header is likely to be format version dependent structure for format version 0x11.
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{| class="wikitable"
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|-
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! Field
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! Offset
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! Length
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! Type
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! Notes
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|-
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| H8
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| 0x0054
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| 4
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| DWORD
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| Offset to section A
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|-
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| H9
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| 0x0058
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| 4
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| DWORD
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| ? Nr of entries in section A
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|-
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| H10
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| 0x005C
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| 4
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| DWORD
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| Offset to section B
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|-
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| H11
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| 0x0060
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| 4
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| DWORD
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| Nr of entries in section B
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|-
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| H12
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| 0x0064
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| 4
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| DWORD
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| Offset to section C
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|-
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| H13
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| 0x0068
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| 4
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| DWORD
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| Length of section C
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|-
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| H14
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| 0x006C
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| 4
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| DWORD
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| Offset to section D
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|-
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| H15
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| 0x0070
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| 4
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| DWORD
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| ? Probably the number of entries in the D section header
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|-
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| H16
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| 0x0074
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| 4
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| DWORD
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| Length of section D
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|-
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| H17
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| 0x0078
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| 8
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| FTIME
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| Latest execution time of executable (FILETIME)
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|-
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| H18
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| 0x0080
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| 16
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| ?
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| ? Possibly structured as 4 DWORD. Observed values: /0x00000000 0x00000000 0x00000000 0x00000000/, /0x47868c00 0x00000000 0x47860c00 0x00000000/
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|-
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| H19
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| 0x0090
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| 4
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| DWORD
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| Execution counter
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|-
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| H20
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| 0x0094
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| 4
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| DWORD?
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| ? Observed values: 1, 2, 3, 4, 5, 6 (XP)
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|-
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|}
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It's worth noting that the name of a carved prefetch file can be restored using the information in field H5 and H6, and its size can be determined by field H4.
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=== Format version ===
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{| class="wikitable"
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|-
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! Value
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! Windows version
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|-
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| 0x11
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| Windows XP, Windows 2003
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|-
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| 0x17
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| Windows Vista, Windows 7
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|-
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| 0x1a
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| Windows 8.1
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|-
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|}
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== Section A ==
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This section contains an array with 20 byte (version 17) or 32 byte (version 23 and 26) entry records.
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The actual format and usage of these entry records is currently not known.
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== Section B ==
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This section contains an array with 12 byte (version 17, 23 and 26) entry records.
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The actual format and usage of these entry records is currently not known.
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== Section C ==
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This section contains an array of UTF-16 little-endian formatted strings with end-of-string characters (U+0000).
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At the end of the section there seems to be alignment padding that can contain remnant values.
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== Section D - Volume information (block) ==
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Section D contains one or more subsections. The number is (most likely) determined by the DWORD at file offset 0x0070. Each subsection refers to directories on an identified volume.
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In this section, all offsets are assumed to be counted from the start of the D section.
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{| class="wikitable"
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|-
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! Field
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! Offset
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! Length
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! Type
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! Notes
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|-
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| DH1
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| +0x0000
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| 4
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| DWORD
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| Offset to volume string (Unicode, terminated by U+0000)
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|-
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| DH2
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| +0x0004
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| 4
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| DWORD
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| Length of volume string (nr of characters, including terminating U+0000)
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|-
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| DH3
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| +0x0008
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| 8
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| FTIME
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| (File time)
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|-
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| DH4
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| +0x0010
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| 4
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| DWORD
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| Volume serial number of volume indicated by volume string
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|-
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| DH5
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| +0x0014
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| 4
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| DWORD
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| ? Offset to section DHS1
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|-
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| DH6
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| +0x0018
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| 4
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| DWORD
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| ? Length of section DHS1 (in bytes)
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|-
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| DH7
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| +0x001C
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| 4
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| DWORD
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| ? Offset to section DHS2
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|-
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| DH8
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| +0x0020
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| 4
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| DWORD
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| ? Nr of strings in section DHS2
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|-
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| ?
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| +0x0024
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| ?
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| ?
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| ? additional 28 bytes (includes one timestamp?)
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|}
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If all the executables and libraries referenced in the C section are from one single disk volume, there will be only one section in the D section. If multiple volumes are referenced by section C, section D will contain multiple sections.  (A simple way to force this situation is to copy, say, NOTEPAD.EXE to a USB drive, and start it from that volume. The corresponding prefetch file will have one D header referring to, e.g. \DEVICE\HARDDISK1\DP(1)0-0+4 (the USB drive), and one to, e.g. \DEVICE\HARDDISKVOLUME1\ (where the .DLLs and other support files were found).
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== See Also ==
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* [[Prefetch]]
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== External Links ==
+

Revision as of 14:20, 12 January 2014

Rekall
Maintainer: Darren Bilby and others
OS: Cross-platform
Genre: Incident Response
License: APL
Website: code.google.com/p/grr/

GRR is an Incident Response Framework focused on Remote Live Forensics.

Contents

See also

External Links

Publications

Presentations

Workshops