Difference between pages "BitLocker Disk Encryption" and "Windows SuperFetch Format"

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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.
+
{{expand}}
  
== BitLocker ==
+
SuperFetch, is a memory management scheme that enhances the least-recently accessed approach with historical information and proactive memory management. [http://technet.microsoft.com/en-us/magazine/2007.03.vistakernel.aspx]
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
+
  
BitLocker has support for partial encrypted volumes.
+
<b>Note that the following format specification are incomplete.</b>
  
=== BitLocker To Go ===
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== SuperFetch DB files ==
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.
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The <tt>Ag*.db</tt> files are of the SuperFetch file format. E.g.
 +
<pre>
 +
AgAppLaunch.db
 +
AgCx_SC*.db
 +
AgGlFaultHistory.db
 +
AgGlFgAppHistory.db
 +
AgGlGlobalHistory.db
 +
AgGlUAD_%SID%.db
 +
AgGlUAD_P_%SID%.db
 +
AgRobust.db
 +
</pre>
  
== How to detect ==
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The SuperFetch DB files can be stored in uncompressed or compressed form, where different version of Windows use different compressed forms:
Volumes encrypted with BitLocker will have a different signature than the standard [[NTFS]] header.
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* Compressed SuperFetch DB - MEMO file format; Windows Vista
 +
* Compressed SuperFetch DB - MEM0 file format; Windows  7
 +
* Compressed SuperFetch DB - MAM file format; Windows 8
  
A BitLocker encrypted volume starts with the "-FVE-FS-" signature.
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=== Compressed SuperFetch DB - MEMO file format ===
 +
The MEM file consists of:
 +
* file header
 +
* compressed blocks
  
A hexdump of the start of the volume should look similar to:
+
This format uses the LZNT1 compression method
<pre>
+
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.....|
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</pre>
+
  
These volumes can also be identified by a GUID:
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==== File header ====
* for BitLocker: 4967d63b-2e29-4ad8-8399-f6a339e3d00
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The file header is 84 bytes of size and consists of:
* for BitLocker ToGo: 4967d63b-2e29-4ad8-8399-f6a339e3d01
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{| class="wikitable"
 +
|-
 +
! Offset
 +
! Size
 +
! Value
 +
! Description
 +
|-
 +
| 0
 +
| 4
 +
| "MEMO" (0x4d, 0x45, 0x4d, 0x4f)
 +
| Signature
 +
|-
 +
| 4
 +
| 4
 +
|
 +
| Uncompressed (total) data size
 +
|-
 +
|}
  
Which in a hexdump of the start of the volume should look similar to:
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==== Compressed blocks ====
<pre>
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The compressed block size is the chunk data size, which is part of the LZNT1 compressed data, + 2 bytes for the size of the chunk header itself.
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>
+
  
== manage-bde ==
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The uncompressed block size is 4096 (0x1000) or the remaining uncompressed data size for the last block.
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>
+
  
To obtain the recovery password for volume C:
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=== Compressed SuperFetch DB - MEM0 file format ===
<pre>
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The MEM file consists of:
manage-bde.exe -protectors -get C: -Type recoverypassword
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* file header
</pre>
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* compressed blocks
  
Or just obtain the all “protectors” for volume C:
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This format uses the LZXPRESS Huffman compression method
 +
 
 +
==== File header ====
 +
The file header is 84 bytes of size and consists of:
 +
{| class="wikitable"
 +
|-
 +
! Offset
 +
! Size
 +
! Value
 +
! Description
 +
|-
 +
| 0
 +
| 4
 +
| "MEM0" (0x4d, 0x45, 0x4d, 0x30)
 +
| Signature
 +
|-
 +
| 4
 +
| 4
 +
|
 +
| Uncompressed (total) data size
 +
|-
 +
|}
 +
 
 +
==== Compressed blocks ====
 +
The file header is followed by compressed blocks:
 +
{| class="wikitable"
 +
|-
 +
! Offset
 +
! Size
 +
! Value
 +
! Description
 +
|-
 +
| 0
 +
| 4
 +
|
 +
| Compressed data size
 +
|-
 +
| 4
 +
| ...
 +
|
 +
| Compressed data
 +
|-
 +
|}
 +
 
 +
The uncompressed block size is 65536 (0x10000) or the remaining uncompressed data size for the last block.
 +
 
 +
=== Compressed SuperFetch DB - MAM file format ===
 +
The MAM file consists of:
 +
* file header
 +
* compressed blocks
 +
 
 +
This format uses the <b>TODO</b> compression method
 +
 
 +
==== File header ====
 +
<b>TODO</b>
 +
 
 +
{| class="wikitable"
 +
|-
 +
! Offset
 +
! Size
 +
! Value
 +
! Description
 +
|-
 +
| 0
 +
| 4
 +
| "MAM\x84" (0x4d, 0x41, 0x4d, 0x84)
 +
| Signature
 +
|-
 +
|}
 +
 
 +
==== Compressed blocks ====
 +
<b>TODO</b>
 +
 
 +
=== Uncompressed SuperFetch DB format ===
 +
<b>TODO</b>
 +
 
 +
==== File header ====
 +
<b>TODO</b>
 +
 
 +
{| class="wikitable"
 +
|-
 +
! Offset
 +
! Size
 +
! Value
 +
! Description
 +
|-
 +
| 0
 +
| 4
 +
| 0x0000000e
 +
| Unknown (Database type or signature?)
 +
|-
 +
| 4
 +
| 4
 +
|
 +
| Uncompressed (total) data size
 +
|-
 +
|}
 +
== TRX files ==
 +
The <tt>Ag*.db.trx</tt> files are of the TRX file format. E.g.
 
<pre>
 
<pre>
manage-bde.exe -protectors -get C:
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AgCx_SC*.db.trx
 
</pre>
 
</pre>
  
== See Also ==
+
<b>Note that the following format specification is incomplete.</b>
* [[BitLocker:_how_to_image|BitLocker: How to image]]
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* [[Defeating Whole Disk Encryption]]
+
  
== External Links ==
+
=== File header ===
 +
The file header is variable of size and consists of:
 +
{| class="wikitable"
 +
|-
 +
! Offset
 +
! Size
 +
! Value
 +
! Description
 +
|-
 +
| 0
 +
| 4
 +
| 1
 +
| Unknown (Version?)
 +
|-
 +
| 4
 +
| 4
 +
|
 +
| Unknown
 +
|-
 +
| 8
 +
| 4
 +
|
 +
| File size
 +
|-
 +
| 12
 +
| 4
 +
|
 +
| Maximum number of records (of the record offsets array)
 +
|-
 +
| 16
 +
| 4
 +
|
 +
| Number of records
 +
|-
 +
| 20
 +
| ...
 +
|
 +
| Record offsets array, where the record offset is a 32-bit integer. Unused record offset are set to 0.
 +
|-
 +
|}
  
* [http://en.wikipedia.org/wiki/BitLocker_Drive_Encryption Wikipedia entry on BitLocker]
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=== Record ===
* [http://www.nvlabs.in/nvbit_bitlocker_white_paper.pdf Accessing Bitlocker volumes from linux], by Nitin Kumar and Vipin Kumar, 2008
+
<b>TODO describe</b>
* [http://jessekornblum.com/publications/di09.html Implementing BitLocker for Forensic Analysis], ''Digital Investigation'', by Jesse D. Kornblum, 2009
+
* [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
+
* [http://technet2.microsoft.com/WindowsVista/en/library/c61f2a12-8ae6-4957-b031-97b4d762cf311033.mspx?mfr=true Microsoft's Step by Step Guide]
+
* [http://technet.microsoft.com/en-us/windowsvista/aa906017.aspx Microsoft Technical Overview]
+
* [http://technet.microsoft.com/en-us/magazine/2009.05.win7.aspx An Introduction to Security in Windows 7]
+
* [http://www.microsoft.com/whdc/system/platform/hwsecurity/BitLockerFAQ.mspx Microsoft FAQ]
+
* [http://www.microsoft.com/downloads/details.aspx?FamilyID=131dae03-39ae-48be-a8d6-8b0034c92555&DisplayLang=en Microsoft Description of the Encryption Algorithm]
+
* [http://secude.com/htm/801/en/White_Paper%3A_Cold_Boot_Attacks.htm Cold Boot Attacks, Full Disk Encryption, and BitLocker]
+
* [http://technet.microsoft.com/en-us/library/hh831412.aspx What's New in BitLocker] in Windows 8
+
  
== Tools ==
+
== See Also ==
* [http://www.hsc.fr/ressources/outils/dislocker/ dislocker]
+
* [[SuperFetch]]
* [[libbde]]
+
 
 +
== External Links ==
 +
* [http://technet.microsoft.com/en-us/magazine/2007.03.vistakernel.aspx Inside the Windows Vista Kernel: Part 2], by [[Mark Russinovich]], March 2007
 +
* [http://blog.rewolf.pl/blog/?p=214 Windows SuperFetch file format – partial specification], by ReWolf, October 5, 2011
  
[[Category:Disk encryption]]
+
[[Category:File Formats]]
[[Category:Windows]]
+

Revision as of 01:41, 23 April 2014

Information icon.png

Please help to improve this article by expanding it.
Further information might be found on the discussion page.

SuperFetch, is a memory management scheme that enhances the least-recently accessed approach with historical information and proactive memory management. [1]

Note that the following format specification are incomplete.

SuperFetch DB files

The Ag*.db files are of the SuperFetch file format. E.g.

AgAppLaunch.db
AgCx_SC*.db
AgGlFaultHistory.db
AgGlFgAppHistory.db
AgGlGlobalHistory.db
AgGlUAD_%SID%.db
AgGlUAD_P_%SID%.db
AgRobust.db

The SuperFetch DB files can be stored in uncompressed or compressed form, where different version of Windows use different compressed forms:

  • Compressed SuperFetch DB - MEMO file format; Windows Vista
  • Compressed SuperFetch DB - MEM0 file format; Windows 7
  • Compressed SuperFetch DB - MAM file format; Windows 8

Compressed SuperFetch DB - MEMO file format

The MEM file consists of:

  • file header
  • compressed blocks

This format uses the LZNT1 compression method

File header

The file header is 84 bytes of size and consists of:

Offset Size Value Description
0 4 "MEMO" (0x4d, 0x45, 0x4d, 0x4f) Signature
4 4 Uncompressed (total) data size

Compressed blocks

The compressed block size is the chunk data size, which is part of the LZNT1 compressed data, + 2 bytes for the size of the chunk header itself.

The uncompressed block size is 4096 (0x1000) or the remaining uncompressed data size for the last block.

Compressed SuperFetch DB - MEM0 file format

The MEM file consists of:

  • file header
  • compressed blocks

This format uses the LZXPRESS Huffman compression method

File header

The file header is 84 bytes of size and consists of:

Offset Size Value Description
0 4 "MEM0" (0x4d, 0x45, 0x4d, 0x30) Signature
4 4 Uncompressed (total) data size

Compressed blocks

The file header is followed by compressed blocks:

Offset Size Value Description
0 4 Compressed data size
4 ... Compressed data

The uncompressed block size is 65536 (0x10000) or the remaining uncompressed data size for the last block.

Compressed SuperFetch DB - MAM file format

The MAM file consists of:

  • file header
  • compressed blocks

This format uses the TODO compression method

File header

TODO

Offset Size Value Description
0 4 "MAM\x84" (0x4d, 0x41, 0x4d, 0x84) Signature

Compressed blocks

TODO

Uncompressed SuperFetch DB format

TODO

File header

TODO

Offset Size Value Description
0 4 0x0000000e Unknown (Database type or signature?)
4 4 Uncompressed (total) data size

TRX files

The Ag*.db.trx files are of the TRX file format. E.g.

AgCx_SC*.db.trx

Note that the following format specification is incomplete.

File header

The file header is variable of size and consists of:

Offset Size Value Description
0 4 1 Unknown (Version?)
4 4 Unknown
8 4 File size
12 4 Maximum number of records (of the record offsets array)
16 4 Number of records
20 ... Record offsets array, where the record offset is a 32-bit integer. Unused record offset are set to 0.

Record

TODO describe

See Also

External Links