Difference between pages "Encase image file format" and "BitLocker Disk Encryption"

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The Encase image file format is used by [[EnCase]] used to store various types of digital evidence e.g.
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'''BitLocker Disk Encryption''' (BDE) is [[Full Volume Encryption]] solution by [[Microsoft]] first included with the Enterprise and Ultimate editions of [[Windows|Windows Vista]]. It is also present in [[Windows|Windows 7]] along with a system for encrypting removable storage media devices, like [[USB]], which is called BitLocker To Go. Unlike previous versions of BitLocker, BitLocker To Go allows the user to protect volumes with a password or smart card.
* disk image (physical bitstream of an acquired disk)
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* volume image
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* memory
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* logical files
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 +
== BitLocker ==
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BitLocker encrypts data with either 128-bit or 256-bit [[AES]] and optionally using a diffuser algorithm called Elephant. The key used to do the encryption, the Full Volume Encryption Key (FVEK) and/or TWEAK key, is stored in the BitLocker metadata on the protected volume. The FVEK and/or TWEAK keys are encrypted using another key, namely the Volume Master Key (VMK). Several copies of the VMK are also stored in the metadata. Each copy of the VMK is encrypted using another key, also know as key-protector key. Some of the key-protectors are:
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* TPM (Trusted Platform Module)
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* Smart card
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* recovery password
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* start-up key
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* clear key; this key-protector provides no protection
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* user password
  
Currently there are 2 versions of the format:
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BitLocker has support for partial encrypted volumes.
* version 1 is (reportedly) based on [[:File:ASR Data's Expert Witness Compression Format.pdf|ASR Data's Expert Witness Compression Format]].
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* version 2 was introduced in EnCase 7, for which a format specification (at least for Ex01) is available, but requires registration.
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The libewf project indicates that the January 2012 version of the version 2 format specification, besides Lx01 not being specified, is sufficient to read the format but not complete.
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== How to detect ==
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Volumes encrypted with BitLocker will have a different signature than the standard [[NTFS]] header.  
  
== Version 1 ==
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A BitLocker encrypted volume starts with the "-FVE-FS-" signature.
The media data can be stored in multiple evidence files, which are called segment files.
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Each segment file consist of multiple sections, which has a distinct section start definition containing a section type.
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Up to EnCase 5 the segment file were limited to 2 GiB, due to the internal 31-bit file offset representation. This limitation was lifted by adding a base offset value in EnCase 6.
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A hexdump of the start of the volume should look similar to:
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<pre>
 +
00000000  eb 58 90 2d 46 56 45 2d  46 53 2d 00 02 08 00 00  |.X.-FVE-FS-.....|
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00000010  00 00 00 00 00 f8 00 00  3f 00 ff 00 00 00 00 00  |........?.......|
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00000020  00 00 00 00 e0 1f 00 00  00 00 00 00 00 00 00 00  |................|
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00000030  01 00 06 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
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00000040  80 00 29 00 00 00 00 4e  4f 20 4e 41 4d 45 20 20  |..)....NO NAME  |
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00000050  20 20 46 41 54 33 32 20  20 20 33 c9 8e d1 bc f4  |  FAT32  3.....|
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</pre>
  
EnCase allows to store the data compressed either using a fast or best level of the deflate compression method.
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These volumes can also be identified by the BitLocker GUID/UUID: 4967d63b-2e29-4ad8-8399-f6a339e3d00 or 4967d63b-2e29-4ad8-8399-f6a339e3d01 for BitLocker ToGo.
EnCase 7 no longer distinguishes between fast or best compression and just provides for either uncompressed or compressed.
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 +
<pre>
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000000a0  3b d6 67 49 29 2e d8 4a  83 99 f6 a3 39 e3 d0 01  |;.gI)..J....9...|
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</pre>
  
Besides digital evidence the evidence files, or segment files, contain a header containing case information.
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== BitLocker To Go ==
The case information which entails date and time of acquisition, an examiner's name, notes on the acquisition, and an optional password.
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Volumes encrypted with BitLocker To Go will have a hybrid encrypted volume, meaning that part of the volume is unencrypted and contains applications to unlock the volume and the other part of the volume is encrypted. The "discovery drive" volume contains BitLocker To Go Reader to read from encrypted volumes on versions of Microsoft [[Windows]] without BitLocker support.
* In EnCase 3 the case information header is stored in the "header" section, which is defined twice within the file and contain the same information.
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* As of EnCase 4 an additional "header2" section was added. The "header" section now appears only once, but the new "header2" section twice.
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== manage-bde ==
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To view the BitLocker Drive Encryption (BDE) status on a running Windows system:
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<pre>
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manage-bde.exe -status
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</pre>
  
The format adds error detection by storing the data with checksums (Adler32), for both the metadata as the data blocks, which are by default 64 x 512 byte sectors (32 KiB).
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To obtain the recovery password for volume C:
As of EnCase 5 the number of sectors per block (chunk) can vary.
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<pre>
EnCase 3F introduced an "error2" section that it uses to record the location and number of bad sector chunks. The way it handles the sections it can't read is that those areas are filled with zero.
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manage-bde.exe -protectors -get C: -Type recoverypassword
Then EnCase displays to the user the areas that could not be read when the image was acquired. The granularity of unreadable chunks appears to be 32K.
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</pre>
As of EnCase 5 the granularity of unreadable chunks can vary.
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Or just obtain the all “protectors” for volume C:
EnCase 3 can store a one-way hash of the data. For a bitstream it does so by calculating e.g. a MD5 hash of the original media data and adds a hash section to the last of the segment file.
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<pre>
As of EnCase 6 the option to store a SHA1 hash was added.
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manage-bde.exe -protectors -get C:
 
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</pre>
 
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EnCase 5 and later have the option to store '''single files''' into the EnCase Logical Evidence File (LEF) or EWF-L01.
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This format changed slightly in EnCase 6 and 7.
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== Version 2 ==
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In EnCase 7 the EWF format was succeeded by the EnCase Evidence File Format Version 2 (EWF2-EX01 and EWF2-LX01).
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EWF2-EX01 is at it's lower levels a different format then EWF-E01 and provides support for:
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* bzip2 compression
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* direct encryption (AES-256) of the section data
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The same features are added to the new logical evidence file format (EWF2-LX01) with the exception of encryption.
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EWF2-EX01, EWF2-LX01 are not backwards compatible with previous EnCase products.
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== See Also ==
 
== See Also ==
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* [[BitLocker:_how_to_image|BitLocker: How to image]]
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* [[Defeating Whole Disk Encryption]]
  
* [[:File:ASR Data's Expert Witness Compression Format.pdf|ASR Data's Expert Witness Compression Format]]
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== External Links ==
* [[EnCase]]
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== External Links ==  
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* [http://en.wikipedia.org/wiki/BitLocker_Drive_Encryption Wikipedia entry on BitLocker]
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* [http://www.nvlabs.in/nvbit_bitlocker_white_paper.pdf Accessing Bitlocker volumes from linux], by Nitin Kumar and Vipin Kumar, 2008
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* [http://jessekornblum.com/publications/di09.html Implementing BitLocker for Forensic Analysis], ''Digital Investigation'', by Jesse D. Kornblum, 2009
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* [https://googledrive.com/host/0B3fBvzttpiiSX2VCRk16TnpDd0U/BitLocker%20Drive%20Encryption%20(BDE)%20format.pdf BitLocker Drive Encryption (BDE) format specification], by the [[libbde|libbde project]], March 2011
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* [http://technet2.microsoft.com/WindowsVista/en/library/c61f2a12-8ae6-4957-b031-97b4d762cf311033.mspx?mfr=true Microsoft's Step by Step Guide]
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* [http://technet.microsoft.com/en-us/windowsvista/aa906017.aspx Microsoft Technical Overview]
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* [http://technet.microsoft.com/en-us/magazine/2009.05.win7.aspx An Introduction to Security in Windows 7]
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* [http://www.microsoft.com/whdc/system/platform/hwsecurity/BitLockerFAQ.mspx Microsoft FAQ]
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* [http://www.microsoft.com/downloads/details.aspx?FamilyID=131dae03-39ae-48be-a8d6-8b0034c92555&DisplayLang=en Microsoft Description of the Encryption Algorithm]
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* [http://secude.com/htm/801/en/White_Paper%3A_Cold_Boot_Attacks.htm Cold Boot Attacks, Full Disk Encryption, and BitLocker]
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* [http://technet.microsoft.com/en-us/library/hh831412.aspx What's New in BitLocker] in Windows 8
  
* [http://encase-enterprise-blog.guidancesoftware.com/2012/01/2nd-generation-encase-evidence-file.html 2nd Generation EnCase Evidence File Technical Specification now Available], Guidance Software, Jan 2012
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== Tools ==
* Requires registration: [http://www.guidancesoftware.com/DocumentRegistration.aspx?did=1000018246 EnCase Evidence File Format Version 2], Guidance Software, Jan 2012
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* [http://www.hsc.fr/ressources/outils/dislocker/ dislocker]
* [http://code.google.com/p/libewf/downloads/detail?name=Expert%20Witness%20Compression%20Format%20%28EWF%29.pdf Expert Witness Compression Format (EWF)].
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* [[libbde]]
* [http://code.google.com/p/libewf/downloads/detail?name=Expert%20Witness%20Compression%20Format%202%20%28EWF2%29.pdf Expert Witness Compression Format (EWF) version 2].
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* [http://www.cfreds.nist.gov/v2/Basic_Mac_Image.html Sample image in EnCase, iLook, and dd format] - From the [[Computer Forensic Reference Data Sets]] Project
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[[Category:Forensics File Formats]]
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[[Category:Disk encryption]]
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[[Category:Windows]]

Revision as of 13:28, 23 December 2013

BitLocker Disk Encryption (BDE) is Full Volume Encryption solution by Microsoft first included with the Enterprise and Ultimate editions of Windows Vista. It is also present in Windows 7 along with a system for encrypting removable storage media devices, like USB, which is called BitLocker To Go. Unlike previous versions of BitLocker, BitLocker To Go allows the user to protect volumes with a password or smart card.

Contents

BitLocker

BitLocker encrypts data with either 128-bit or 256-bit AES and optionally using a diffuser algorithm called Elephant. The key used to do the encryption, the Full Volume Encryption Key (FVEK) and/or TWEAK key, is stored in the BitLocker metadata on the protected volume. The FVEK and/or TWEAK keys are encrypted using another key, namely the Volume Master Key (VMK). Several copies of the VMK are also stored in the metadata. Each copy of the VMK is encrypted using another key, also know as key-protector key. Some of the key-protectors are:

  • TPM (Trusted Platform Module)
  • Smart card
  • recovery password
  • start-up key
  • clear key; this key-protector provides no protection
  • user password

BitLocker has support for partial encrypted volumes.

How to detect

Volumes encrypted with BitLocker will have a different signature than the standard NTFS header.

A BitLocker encrypted volume starts with the "-FVE-FS-" signature.

A hexdump of the start of the volume should look similar to:

00000000  eb 58 90 2d 46 56 45 2d  46 53 2d 00 02 08 00 00  |.X.-FVE-FS-.....|
00000010  00 00 00 00 00 f8 00 00  3f 00 ff 00 00 00 00 00  |........?.......|
00000020  00 00 00 00 e0 1f 00 00  00 00 00 00 00 00 00 00  |................|
00000030  01 00 06 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000040  80 00 29 00 00 00 00 4e  4f 20 4e 41 4d 45 20 20  |..)....NO NAME  |
00000050  20 20 46 41 54 33 32 20  20 20 33 c9 8e d1 bc f4  |  FAT32   3.....|

These volumes can also be identified by the BitLocker GUID/UUID: 4967d63b-2e29-4ad8-8399-f6a339e3d00 or 4967d63b-2e29-4ad8-8399-f6a339e3d01 for BitLocker ToGo.

000000a0  3b d6 67 49 29 2e d8 4a  83 99 f6 a3 39 e3 d0 01  |;.gI)..J....9...|

BitLocker To Go

Volumes encrypted with BitLocker To Go will have a hybrid encrypted volume, meaning that part of the volume is unencrypted and contains applications to unlock the volume and the other part of the volume is encrypted. The "discovery drive" volume contains BitLocker To Go Reader to read from encrypted volumes on versions of Microsoft Windows without BitLocker support.

manage-bde

To view the BitLocker Drive Encryption (BDE) status on a running Windows system:

manage-bde.exe -status

To obtain the recovery password for volume C:

manage-bde.exe -protectors -get C: -Type recoverypassword

Or just obtain the all “protectors” for volume C:

manage-bde.exe -protectors -get C:

See Also

External Links

Tools