Foremost

Description

Foremost is a tool that recovers files using their headers, footers and data structures.

Recover files from a disk image based on file types specified by the user using the -t switch. Supported files:

• jpg: Support for the JFIF and Exif formats including implementations used in modern digital cameras.
• gif
• png
• bmp: Support for windows bmp format.
• avi
• exe: Support for Windows PE binaries, will extract DLL and EXE files along with their compile times.
• mpg: Support for most MPEG files (must begin with 0x000001BA)
• wav
• riff: This will extract AVI and RIFF since they use the same file format (RIFF). note faster than running each separately.
• wmv: Note may also extract wma files as they have similar format.
• mov
• pdf
• ole: This will grab any file using the OLE file structure. This includes PowerPoint, Word, Excel, Access, and StarWriter
• doc: Note it is more efficient to run OLE as you get more bang for your buck. If you wish to ignore all other ole files then use this.
• zip: Note is will extract .jar files as well because they use a similar format. Open Office docs are just zip'd XML files so they are extracted as well. These include SXW, SXC, SXI, and SX? for undetermined OpenOffice files. Office 2007 files are also XML based (PPTX,DOCX,XLSX)
• rar
• htm
• cpp: C source code detection, note this is primitive and may generate documents other than C code.
• mp4: Support for MP4 files.
• all: Run all pre-defined extraction methods. [Default if no -t is specified]

Syntax

foremost [-h] [-V] [-d] [-vqwQT] [-b <blocksize>] [-o <dir>] [-t <type>] [-s <num>] [-i <file>]

Options

-h

Show a help screen and exit.

-V

Show copyright information and exit.

-d

Turn on indirect block detection, this works well for Unix file systems.

-T

Time stamp the output directory so you don't have to delete the output dir when running multiple times.

-v

Enables verbose mode. This causes more information regarding the current state of the program to be displayed on the screen, and is highly recommended.

-q

Enables quick mode. In quick mode, only the start of each sector is searched for matching headers. That is, the header is searched only up to the length of the longest header. The rest of the sector, usually about 500 bytes, is ignored. This mode makes foremost run considerably faster, but it may cause you to miss files that are embedded in other files. For example, using quick mode you will not be able to find JPEG images embedded in Microsoft Word documents.

Quick mode should not be used when examining NTFS file systems. Because NTFS will store small files inside the Master File Table, these files will be missed during quick mode.

-Q

Enables Quiet mode. Most error messages will be suppressed.

-w

Enables write audit only mode. No files will be extracted.

-a

Enables write all headers, perform no error detection in terms of corrupted files.

-b number

Allows you to specify the block size used in foremost. This is relevant for file naming and quick searches. The default is 512. ie. foremost -b 1024 image.dd

-k number

Allows you to specify the chunk size used in foremost. This can improve speed if you have enough RAM to fit the image in. It reduces the checking that occurs between chunks of the buffer. For example if you had > 500MB of RAM. ie. foremost -k 500 image.dd

-i file

The file is used as the input file. If no input file is specified or the input file cannot be read then stdin is used.

-o directory

Recovered files are written to the directory directory.

-c file

Sets the configuration file to use. If none is specified, the file "foremost.conf" from the current directory is used, if that doesn't exist then "/etc/foremost.conf" is used. The format for the configuration file is described in the default configuration file included with this program. See the CONFIGURATION FILE section below for more information.

-s number

Skips number blocks in the input file before beginning the search for headers. ie. foremost -s 512 -t jpeg -i /dev/hda1

Configuration file

The configuration file is used to control what types of files foremost searches for. A sample configuration file, foremost.conf, is included with this distribution. For each file type, the configuration file describes the file's extension, whether the header and footer are case sensitive, the maximum file size, and the header and footer for the file. The footer field is optional, but header, size, case sensitivity, and extension are not!

Any line that begins with a pound sign is considered a comment and ignored. Thus, to skip a file type just put a pound sign at the beginning of that line.

Headers and footers are decoded before use. To specify a value in hexadecimal use \x[0-f][0-f], and for octal use \[1-9][1-9][1-9]. Spaces can be represented by \s. Example: "\x4F\123\I\sCCI" decodes to "OSI CCI".

To match any single character (aka a wildcard) use a ?. If you need to search for the ? character, you will need to change the wildcard line *and* every occurrence of the old wildcard character in the configuration file. Do not forget those hex and octal values! ? is equal to \x3f and \063.

Examples

Search for jpeg format skipping the first 100 blocks

foremost -s 100 -t jpg -i image.dd

Only generate an audit file, and print to the screen (verbose mode)

foremost -av image.dd

Search all defined types

foremost -t all -i image.dd

Search for gif and pdf's

foremost -t gif,pdf -i image.dd

Search for office documents and jpeg files in a Unix file system in verbose mode.

foremost -vd -t ole,jpeg -i image.dd

Run the default case

foremost image.dd