Friday, May 27, 2011

Virtualizing Raw Disk Images

I have heard a lot of people ask about how to forensically handle raw (dd) disk images of systems that have been encrypted with whole disk encryption. Both PGP and Truecrypt support the use Recovery/Rescue ISO's to decrypt drives without booting the OS (Note: an administrator pass phrase is still going to be required). So if you could boot the raw image in VMware, for example, then you could mount the ISO and decrypt the image.

One Windows tool, Live View, can be used to convert dd images to a vmdk (Virtual Machine Disk Format) file. Live View was created at Carnegie Mellon University in 2009 but it unfortunately has not been updated since then. Consequently, there is no support for modern versions of Windows or VMWare Workstation or Server.

Fortunately, Tasos Laskos, expanded on their work and created the raw2vmdk utility. Raw2vmdk is an open source, OS independent (requires JRE 1.6.0_18 or higher), command line utility that can create a vmdk file with the appropriate disk type parameters that will allow you to boot directly from a dd image.

The readme outlines the syntax of the utility (Note: if disk type is not specified then it defaults to IDE).
java -Dtype=<ide|buslogic|lsilogic|legacyESX> -jar raw2vmdk.jar <raw image> <vmdk outfile>
Note the syntax of the slashes when running the command on a Windows system.
java -jar raw2vmdk.jar D:\\data001.dd D:\\data001.vmdk
Once run, the analysis and creation of the vmdk file only takes a few seconds.


Raw2vmdk creates a properly formatted vmdk with the appropriate path to the raw image, disk type, and parameters.
# Disk DescriptorFile
version=1
encoding="UTF-8"
CID=5c643bba
parentCID=ffffffff
isNativeSnapshot="no"
createType="monolithicFlat"

# Extent description
RW 156301488 FLAT "D:\data001.dd" 0

# The Disk Data Base
#DDB

ddb.virtualHWVersion = "7"
ddb.longContentID = "bf304434123a064225efde635c643bba"
ddb.uuid = "60 00 C2 91 8e 73 27 62-43 58 3b f8 05 ae 2e a0"
ddb.geometry.cylinders = "1023"
ddb.geometry.heads = "255"
ddb.geometry.sectors = "19"
ddb.adapterType = "ide"
The monolithic flat disk type is a pre-allocated disk type that is stored in one file. This format also supports raw dd images. Once the creation of the file is complete, create a new virtual system as you normally would within Vmware Workstation or Server and point the hard disk to the newly created vmdk file.


You should now able to boot your image within VMware (assuming it includes the boot partition). A word of caution, however. Always follow IR and Forensics best practices and use a second copy of your raw image. I also like to create the virtual system and vmdk in a separate folder from the raw dd image, so if the VM is accidentally deleted it does not also delete your raw disk image.

Happy Hunting.

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