Bodyfile format

The bodyfile (or body file) format is an output format, as far as known, introduced by the SleuthKit. SleuthKit tools such as fls or ils, use a bodyfile for intermediate storage. These bodyfiles are then provided as input to the mactime tool.

The bodyfile format has been adopted by many other, non-SleuthKit tools, and does not appear to have a strict definition. This document explains the implementation used by the dfImageTools project.

The dfImageTools project uses a bodyfile format that has been derived from the format used by SleuthKit 3.0 and later. Changes have been made to overcome several shortcomings of the original format.

A bodyfile consists of one or more lines with 11 pipe-character (’|’) delimited values. The SleuthKit documentation defines these values as:

MD5|name|inode|mode_as_string|UID|GID|size|atime|mtime|ctime|crtime
Value Description
MD5 MD5 of the file entry data.
name Full path of the file entry.
inode Unique identifier of the file entry within the file system.
mode_as_string POSIX file mode represented as a string.
UID POSIX user identifier (UID) of the user owning the file entry.
Note that this value will be empty if the file system has no user identifier equivalent.
GID POSIX group identifier (GID) of the group owning the file entry.
Note that this value will be empty if the file system has no group identifier equivalent.
size Size of the data of the file entry.
Note that the list_file_entries.py script only reports the size of "regular" file entries.
atime File entry last access time.
mtime File entry last modification time.
ctime File entry last change (or entry modification) time.
crtime File entry creation time.

MD5 value

The SleuthKit documentation does not define the MD5 values. From observations the following convention is used:

  • ‘0’ if “hashing” is disabled;

  • ‘00000000000000000000000000000000’ if “hashing” is enabled but no MD5 was calculated;

  • ‘[0-9a-f]{32}’ if a MD5 was calculated.

Name value

The name value typically contains a full path of the file entry, but it can also contain a symobolic link target using the convention:

${PATH} -> ${SYMBOLIC_LINK_TARGET}

Bodyfile entries where the time values are extracted for an NTFS $FILE_NAME attribute the ‘($FILE_NAME)’ suffix is added to the name value.

${PATH} (\$FILE_NAME)

Note that at the moment the list_file_entries.py script does not combine a symbolic link target and ‘($FILE_NAME)’ suffix.

The list_file_entries.py script always uses forward slash (’/’) as the path segment separator, even for NTFS. The following characters are escaped with a backslash (’\’):

  • U+0000 - U+0019 (C0 control codes, non-printable)

  • U+002f (forward slash ‘/’, used as path segment separator)

  • U+003a (colon ‘:’, used as data stream separator)

  • U+005c (backslash ‘\’, used as escape character)

  • U+007c (pipe ‘|’, used as value delimiter)

  • U+007f (delete, non-printable)

  • U+0080 - U+009f (C1 control codes, non-printable)

Paths are prefixed with a partition or volume indicator if the list_file_entries.py script is used to list multiple partitions and/or volumes at once.

Inode value

The inode value contains an unique identifier of the file entry within the file system, which for some file systems is the inode number.

For the dfVFS FAT back-end the offset, relative to the start of the volume, to the directory entry is used.

For the dfVFS NTFS back-end the convention ${MFT_ENTRY}-${SEQUENCE_NUMBER} is used instead of the non-portable metadata address used by the SleuthKit tools.

Mode_as_string value

The mode_as_string value contains a POSIX file mode represented as a string, for example ‘drwxr-xr-x’.

The first character represents the file entry type:

  • ‘-’ to indicate a “regular” file (S_IFREG) or unknown type

  • ‘b’ to indicate a block device (S_IFBLK)

  • ‘c’ to indicate a character device (S_IFCHR)

  • ‘d’ to indicate a directory (S_IFDIR)

  • ‘l’ to indicate a symbolic link (S_IFLNK)

  • ‘p’ to indicate a named-pipe (S_IFIFO)

  • ‘s’ to indicate a socket (S_IFSOCK)

The SleuthKit specific ‘r’ type indicator is not used by the dfImageTools project.

The remaining characters are the read, write and execute permissions for owner, group and other.

The SleuthKit specific [-dlr]/ prefix is not used by the dfImageTools project.

FAT and NTFS

For the FAT and NTFS dfVFS back-end, dfImageTools uses the following approach to generate a mode_as_string value.

The first character represents the file entry type:

  • ‘-’ to indicate a “regular” file or unknown type

  • ‘d’ to indicate a directory, e.g. for NTFS if the file entry has an $I30 index and is not a symbolic link

  • ‘l’ to indicate a symbolic link, e.g. for NTFS if the file entry has a $REPARSE_POINT attribute with tag 0xa000000c

The remaining characters are based on the file attribute flags and will be ‘r-xr-xr-x’ if FILE_ATTRIBUTE_READONLY or FILE_ATTRIBUTE_SYSTEM is set or ‘rwxrwxrwx’ otherwise.

Time values

Time values are provided as a number of seconds since January 1, 1970 00:00:00 (epoch) without a time zone, where negative time values predate the epoch. A fraction of second is provided if the original time value has a higher datetime value granularity.

Note that a time value of 0 represent not-set or that the original time value, before conversion to POSIX time, was 0.

Also see