NTFS Implementation Notes

NOTE: This was copied from skins_ntfs.txt. It will need some updating and wiki'ing help.

Introduction

The NTFS file system is used in all critical Microsoft Windows systems. It is an advanced file system that is significantly different from the UNIX file systems that the original TCT was designed for. This document gives a quick overview of NTFS and how it was implemented. The biggest difference is the use of Alternate Data Streams (ADS) when specifying a meta data structure.

The Sleuth Kit allows one to investigate an NTFS image in the same ways as any UNIX image, including:

• Creation of ASCII timeline of file activity
• Cluster analysis and mapping between clusters and MFT entries
• MFT analysis and mapping between MFT entries and file names
• File and directory level analysis including deleted files

Metadata Addresses

The Sleuth Kit allows one to view all aspects of the NTFS structure. It does this using a special Metadata Address format. With UNIX you only need to reference the inode number because there is only one piece of content for the file. With NTFS, one can either specify just the MFT number and the default data attribute is used or the type can be specified by adding it to the end of the MFT entry, 36-128 for example. If more than one attribute of the same type exists, then the id can be used after the type, 36-128-5 for example.

All Sleuth Kit tools can take MFT values in any of the above formats and output from the tools will also be in one of the above formats. For example, the istat tool will list all attributes a file has. To get the details of MFT entry 49, use:

    # istat -f ntfs ntfs.dd 49
    MFT Entry: 49
    Sequence: 2
    Allocated
    UID: 0
    DOS Mode: File
    Size: 15
    Links: 1
    Name: multiple.txt

    $STANDARD_INFORMATION Times:
    File Modified:  Mon Nov  5 19:58:27 2001
    MFT Modified:   Mon Nov  5 19:58:27 2001
    Accessed:       Mon Nov  5 19:58:27 2001

    $FILE_NAME Times:
    Created:        Mon Nov  5 19:57:29 2001
    File Modified:  Mon Nov  5 19:57:29 2001
    MFT Modified:   Mon Nov  5 19:57:29 2001
    Accessed:       Mon Nov  5 19:57:29 2001

    Attributes: 
    Type: $STANDARD_INFORMATION (16-0)   Name: N/A   Resident   size: 72
    Type: $FILE_NAME (48-2)   Name: N/A   Resident   size: 90
    Type: $OBJECT_ID (64-3)   Name: N/A   Resident   size: 16
    Type: $DATA (128-1)   Name: $Data   Resident   size: 15
    Type: $DATA (128-5)   Name: overhere   Resident   size: 26

We see that it has 5 attributes, all of them are resident (notice the small sizes). Two of the attributes are $DATA attributes (128-1 and 128-5). The full name of 128-1 is 'multiple.txt' and the full name of 128-5 is 'multiple.txt:overhere'.

The following command would display the default data attribute (128-1):

	# icat -f ntfs ntfs.dd 49

The following is the same:

	# icat -f ntfs ntfs.dd 49-128-1

The following displays the other data stream:

    # icat -f ntfs ntfs.dd 49-128-5

As an additional example, the raw format of the $FILE_NAME attribute can be viewed using:

    # icat -f ntfs ntfs.dd 49-48-2

The output of the above command would be a combination of UNICODE characters and other binary data (I would recommend just using the output of the istat command for this type of data).

The output of the fls command is similar:

    # fls -f ntfs ntfs.dd
    <...>
    r/r 48-128-1:   test-1.txt
    r/r 49-128-1:   multiple.txt
    r/r 49-128-5:   multiple.txt:NEW
    r/r 50-128-1:   test-2.txt
    <...>

This allows you to easily identify all data streams.

Note that Autopsy can automate this process for you and allows you to view all attributes.

  http://www.sleuthkit.org/autopsy

What TSK Cannot Currently Do

There are a few things that The Sleuth Kit is not yet able to do with NTFS:

• The Security Descriptors are not yet analyzed. Therefore, the exact ACLs of the object can not be displayed.
• Directories that are indexed by a descriptor other than the file name, are not supported.
• Encrypted files are not supported