Difference between pages "Hard Drive Passwords" and "Encase image file format"

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Some hard drives support passwords. These passwords can be implemented in computer's operating system, its BIOS, or even in the hard drive's firmwarePasswords implemented in the OS are the easiest to remove, those in the firmware are the hardest.  
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[[EnCase]] uses a closed format for images which is reportedly based on [http://www.asrdata.com/SMART/whitepaper.html ASR Data's Expert Witness Compression Format]. The evidence files, or E01 files, contain a physical bitstream of an acquired disk, prefixed with a '"Case Info" header, interlaced with checksums (Adler32) for every block of 64 x 512 byte sectors (32 KiB), and followed by a footer containing an MD5 hash for the entire bitstreamContained in the header are the date and time of acquisition, an examiner's name, notes on the acquisition, and an optional password; the header concludes with its own checksum.
  
Sometimes people use the term "password" but the hard drive is really [[Full Disk Encryption|encrypted]], and the password is used to unlock a decryption key. These passwords cannot be removed — the encryption key must be cracked or discovered through another means.
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EnCase can store media data into multiple evidence files, which are called segment files. Each segment file consist of multiple sections. Each section consist of a section start definition. This contains a section type.
  
=Vendors=
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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 using a base offset work around in EnCase 6.
* Disklabs (www.disklabs.com) is able to remove some forms of hard drive passwords.
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* Dell will assist law enforcement in removing the passwords from password-protected hard drives. You need to provide Dell with a copy of the search warrant and the computer's service tag #. Reportedly this can be done over the phone, once you have a good relationship with Dell.
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At least from Encase 3 the case info header is contained in the "header" section, which is defined twice within the file and contain the same information.
  
* [http://www.hdd.profesjonalnie.pl/to.php Seagate HDD Service Device for 2,5" drives BASIC Kit]: The tool works with 2,5" drives of Seagate. Main functionality - ATA PASSWORD removal from 2,5" drives.
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With Encase 4 an additional "header2" section was added. The "header" section now appears only once, but the new "header2" section twice.
  
* [http://www.acelaboratory.com/pc3000.htm PC-3000 for Windows] has "An opportunity to unlock USER and MASTER passwords used in a HDD".
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Version 3 of The Encase F introduced an "error2" sections 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. 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.
  
* [http://www.hdd-tools.com/products/rrs/ With Repair Station you can remove an unknown ATA-password; both security levels are supported: High and Maximum]
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Within Encase 5 the number of sectors per block (chunk) can vary.
  
* [http://www.vogon-investigation.com/password-cracker-solution.htm Using the Vogon Password Cracker POD, the protection from the drive can be removed]
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Encase from at least in version 3 can hash the data of the media it acquires.
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It does this by calculating a MD5 hash of the original media data and adds a hash section
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to the last of the segment files.
  
* [http://www.salvationdata.com SalvationData] sells a system for "Stage 2 physical data damage" recovery from HDDs. The company sells tools for swapping out platters from one drive into another drive, changing the firmware on drives, and other kinds of operations.
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Later versions of Encase 6 included the option to store a MD5 and/or SHA1 hash.
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In EnCase 7 the EWF format was succeeded by the EnCase Evidence File Format Version 2 (EWF-EX01 and EWF-LX01).
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Guidance has made a specification of the EWF-EX01 format public.
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EnCase 7 also uses a different version of EWF-L01 then its predecessors and no longer distinguishes between fast or best compression.
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EWF-EX01 is at it's lower levels a different format then EWF-E01 and provides support for:
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* bzip compression
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* direct encryption (AES-256) of the data
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The same features are added to the new logical evidence file format (Lx01) with the exception of encryption.
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EWF-EX01, EWF-LX01 are not backwards compatible with previous EnCase products.
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== See Also ==
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[[EnCase]]
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== External Links ==
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* [https://downloads.sourceforge.net/project/libewf/documentation/EWF%20file%20format/Expert%20Witness%20Compression%20Format%20%28EWF%29.pdf Expert Witness Compression Format (EWF)].
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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]]

Revision as of 15:40, 29 June 2012

EnCase uses a closed format for images which is reportedly based on ASR Data's Expert Witness Compression Format. The evidence files, or E01 files, contain a physical bitstream of an acquired disk, prefixed with a '"Case Info" header, interlaced with checksums (Adler32) for every block of 64 x 512 byte sectors (32 KiB), and followed by a footer containing an MD5 hash for the entire bitstream. Contained in the header are the date and time of acquisition, an examiner's name, notes on the acquisition, and an optional password; the header concludes with its own checksum.

EnCase can store media data into multiple evidence files, which are called segment files. Each segment file consist of multiple sections. Each section consist of a section start definition. This contains a section type.

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 using a base offset work around in EnCase 6.

At least from Encase 3 the case info header is contained in the "header" section, which is defined twice within the file and contain the same information.

With Encase 4 an additional "header2" section was added. The "header" section now appears only once, but the new "header2" section twice.

Version 3 of The Encase F introduced an "error2" sections 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. 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.

Within Encase 5 the number of sectors per block (chunk) can vary.

Encase from at least in version 3 can hash the data of the media it acquires. It does this by calculating a MD5 hash of the original media data and adds a hash section to the last of the segment files.

Later versions of Encase 6 included the option to store a MD5 and/or SHA1 hash.

In EnCase 7 the EWF format was succeeded by the EnCase Evidence File Format Version 2 (EWF-EX01 and EWF-LX01). Guidance has made a specification of the EWF-EX01 format public.

EnCase 7 also uses a different version of EWF-L01 then its predecessors and no longer distinguishes between fast or best compression.

EWF-EX01 is at it's lower levels a different format then EWF-E01 and provides support for:

  • bzip compression
  • direct encryption (AES-256) of the data

The same features are added to the new logical evidence file format (Lx01) with the exception of encryption.

EWF-EX01, EWF-LX01 are not backwards compatible with previous EnCase products.

See Also

EnCase

External Links