Monday, 17 August 2009

Vista Volume Shadow Copy issues

Volume shadow copies in Vista are often the elephant sat in the corner in many cases. We know they exist and we know they can contain lots of data, but we often choose to ignore them.
A recent case required some keyword searches and an examination of picture files. A the completion of the keyword search most of the hits were within files with names similar to

The view pane within Encase 6.14 displayed the contents in a nice light blue colour which I now know is a new feature in 6.14 to indicate the contents of uninitialised files. The files were all located within the System Volume Information folder on the root of the volume and are the Vista Volume Shadow Copies. By default 15% of the capacity of the volume is allocated by Vista to store these copies. The C4P graphics extractor enscript carved most of the notable pictures out shadow copies also.
At this stage I have known examiners report their findings alluding to the fact that that the notable artefacts are within the file {bab9c293-d150-12dc-a44f-021d253da909}{3708876a-d176-4f38-b7bb-05036c6bb821}. In most cases I think you need to drill down further. In order to do this I mounted my Vista image with Encase PDE and used Liveview 0.7b to create a working VM using VMWare Workstation 6. Having logged into my suspects account I ran a command prompt as administrator and entered the command
vssadmin list shadows /for=c:\

This provided a nice list of available shadow copies. Having selected one I entered the command (updated 13th Jan 2010)

mklink /d c:\shadow_copy7 \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy7\

This created a symbolic link in the root of C which in Windows Explorer at any rate appears exactly like a shortcut to a folder. Clicking on it produced the error message shown below

I believed this error is probably generated by a permissions issue (SEE UPDATE BELOW), however I was not able to overcome it and Rob Lee over at Sans Computer Forensics suggests this methodology does not work. I think Jimmy Weg however has had some success with a program written by Dan Mares - VSS.exe. I therefore turned to ShadowExplorer version 0.4.382.0. This program allows the user to view the contents of Volume Shadow Copies that exist on any volumes within the installed system. The contents are displayed in an Explorer like view allowing the user to export out any file or folder to an export directory. I exported the User profile I was interested in to an export directory. Unfortunately it seems that only the Last Written date is preserved in this process and all other time stamps are tripped. I then tried to copy this export directory out of the VM to my workstation and encountered errors (probably due to files within the profile with illegal windows file names). To overcome this I zipped up the export directory and copied the zip out of the VM. Once unpacked I then added the exported folders into Encase as single files and created logical evidence files from them.
Having done this I was able to resolve most of my keyword search hits and pictures to actual files as opposed to being simply within a volume shadow copy.

UPDATE 13th January 2010
The issue I had with the mklink command was due to a missing \  but not the trailing slash referred to in some comments below.  The correct command is 

mklink /d c:\shadow_copy7 \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy7\

Sunday, 2 August 2009

You wait all day for a bus then two come along at once...

Probably not an entirely accurate title but I came across two enscripts the other day both of which are aimed at quickly triaging the results of a comprehensive Internet History search. Users of this functionality within Encase version 6 will know that often you can be faced with reviewing hundreds of thousands of entries on the records tab. Many times all you need is evidence of user inputted search terms. There are conditions available to start sorting the wheat from the chaff however it is difficult for these conditions to be totally focussed due to the variation in url formation. This is where both enscripts come in as they are both designed to parse the actual search term used from a variety of search engine urls.

Searchterms V 1.1 parses out the search term used and where possible the time and date it was carried out into note bookmarks. The enscript has been written to support a claimed 145 separate search engines.

Internet Search Term Finder parses out unique search terms to Log Record bookmarks and stores the term along with its associated url. The script is in fact an Enpack so it is difficult to determine exactly how it works, however it seems to base its search on elements from the query url. A neat feature is that it is configurable, allowing the addition of a new prefix (to the query string) to cater for a different or new search engine.

Within an XP Pro SP3 VM I carried out a series of searches utilising the Firefox v3.0.11, Internet Explorer v8, Opera v9.64 and Safari v4.0.2 browsers. I ran the Search for internet history Comprehensive search option within Encase 6.14 and established that all my searches had been parsed into the records tab, with the exception of those carried out with Safari v4.0.2. It turns out that Encase 6.14 does not support parsing internet history from this version of Safari.

I then ran both Enscripts and can report that both parsed out my test search terms from the records tab. The results can be viewed within bookmarks. For me the output of the Internet Search Term Finder is preferable and it usefully creates a Log Records bookmark which allows the easy export of results into a spreadsheet. Both successfully hit the spot in respect to users quickly reviewing search terms within internet history.

Update 15 Sept 2009
Dan Fenwick has kindly updated his Internet Search Term Finder (to v1.1.1). The script now can remove duplicates and separates the results by device. Even more useful - thanks Dan.