Leonardo Musumeci

Metadata information from documents can be a great source of information for investigators and it’s value has often been discussed before. Documents created using Microsoft Office often come up during investigations. There are several scripts and tools out there to read the proprietary binary format of Office documents created using Office 2003 and earlier versions so there is not more to add to those tools. Yet there aren’t that many tools out there that can list the metadata information from the new format that Office 2007 uses, OpenXML. So I decided to examine it a bit further.

Microsoft has already published a good enough document describing the structure of OpenXML [1]. Essentially a document created in the OpenXML document format is a compressed file, using the well known ZIP format, so it can be easily opened using any ZIP tool (for instance by modifying the name of the document from document.docx to document.zip and using a standard ZIP tool).

Inside the ZIP file are predefined structures of files, mostly XML files that describe the document and it’s content. So it can be easily read using standard available libraries in scripting languages such as Perl.

According to Microsoft a folder is created inside the ZIP archive called “_rels”. This folder contains a file named “.rels” which defines the root relationships within the package. This should be the first place to be able to parse the content of the document. Whithin the .res file you find tags that define the relationship of the document:

<Relationship Id="someID" Type="relationshipType" Target="targetPart"/>

Metadata is stored in files that contain a type of “*properties”, most notable the “core-properties” and “extended-properties”. These files are usually stored in the following location:

• docProps/core.xml
• docProps/app.xml

These files then contain the actual metadata information, such as document creator, last saved by information, etc. To be able to display the metadata information it is necessary to extract and parse these documents.

To do this I wrote the script read_open_xml.pl that parses the contents of the .rels file to locate metadata information from the document and then extracts the metadata and prints it to the screen. Example usage is:

./read_open_xml.pl test.docx

==========================================================================
 cmd line: ./read_open_xml.pl test.docx
==========================================================================

Document name: test.docx
Date: Tue Jun  9 16:51:23 GMT 2009

--------------------------------------------------------------------------
File Metadata
--------------------------------------------------------------------------
 title = my company template
 subject = Document template
 creator = Kristinn Gudjonsson
 keywords = template, word
 description =
 lastModifiedBy = Kristinn Gudjonsson
 revision = 3
 lastPrinted = 2008-08-15T10:14:00Z
 created = 2008-08-15T10:14:00Z
 modified = 2008-08-15T10:14:00Z
 category = template
--------------------------------------------------------------------------
Application Metadata
--------------------------------------------------------------------------
 Template = my_template.dot
 TotalTime = 0
 Pages = 2
 Words = 159
 Characters = 908
 Application = Microsoft Word 12.1.2
 DocSecurity = 0
 Lines = 7
 Paragraphs = 1
 ScaleCrop = false
 Manager = Some dude
 Company = My Company
 LinksUpToDate = false
 CharactersWithSpaces = 1115
 SharedDoc = false
 HyperlinksChanged = false
 AppVersion = 12.0258

copyright, Kristinn Gudjonsson, 2009

The script also reads the character encoding of the XML documents and encodes the output accordingly.

The script was created to be used in Linux however I modified the script slightly so it should work on a Windows OS (tested on a Win XP SP3 using ActivePerl 5.10). You can get the Windows version here. The Windows version has not been tested as well as the Linux one, so it might still be little bit more unstable (there are some installation information contained within the script itself)

Source : Office 2007 Metadata

From the press release:

Unlike existing computer forensics solutions, EnCase Portable runs on a USB drive, rather than a laptop, and enables the user to easily and rapidly boot a target computer to the USB drive, and run a pre-configured data search and collection job. The ease-of-use and ultra-portability of EnCase Portable creates exciting new possibilities in data acquisition. Even personnel untrained in computer forensics can forensically acquire documents, Internet history and artifacts, images, and other digital evidence, including entire hard drives, with a few simple keyboard clicks.

Source : New Computer Snooping Tool