bulk_extractor - Scans a disk image for regular expressions and other content.
bulk_extractor -o output_dir [options] [ image | -R dir ]
bulk_extractor scans a disk image (or any other file) for a large number
of pre-defined regular expressions and other kinds of content. These items are
called features. When it finds a feature, bulk_extractor writes
the output to an output file. Each line of the output file contains a byte
offset at which the feature was found, a tab, and the actual feature. Features
therefore cannot contain the end-of-line character.
bulk_extractor includes native support for EnCase (.E01)
and AFFLIB (.aff) files, if it compiled and linked on a system containing
those libraries. Alternatively, the -R option can be used to recursively
scan and process a directory of individual files (disk images in such a
directory will be treated as files, not as disk images).
bulk_extractor is multi-threaded. By specifying the
-j option, multiple copies of the program can be run. Each thread
writes its results into its own feature file. The files are then combined by
the primary thread when all of the secondary threads complete.
bulk_extractor is a two-phase program. In phase 1 the
features are extracted. In phase 2 a histogram is created of relevant
bulk_extractor will also create a wordlist of all
the words that are found in the disk image. This can be used as a dictionary
for cracking encryption.
The options are as follows:
These commands are useful for tuning operation:
- -o outdir
- Specifies the output directory, which will be created by
bulk_extractor if necessary. If the output directory contains data
from a partial bulk_extractor run, bulk_extractor will
attempt to resume where the previous run left off.
- -b bannerfile.txt
- Read the contents of bannerfile.txt and stamp it at the beginning
of each output file. This might be useful if you have some kind of privacy
banner that needs to be stamped at the top of all of your files.
- -r alert_list.txt
- Specifies an alert list, (or red list), which is a list of terms
that, if found, will be specifically flagged in a special alert
file that begins with the letters ALERT. The alert list may
contain individual terms, which must be found in their entirity and are
case-sensitive, or wildcards with standard Unix globbing (e.g.
*@company.com). Globbed terms are case-insensitive.
- -w stop_list.txt
- Specifies a stop list, (or white list), which is a list of terms
that, if found, will be placed in a special stopped file (rather
than in the main file). The whitelist may also contain globbed terms.
- -s frac[:passes]
- Specify random sampling parameters.
- -p path/format
- Open a disk image and print the information found at path. The
format specification may be r for raw output and h
for hex output.
Specify -p - for interactive mode.
Specify -p -http for HTTP mode.
- -F <rfile>
- Specifies a file of regular expressions to be used as search terms.
- -f <regex>
- Specifies a regular expression to be used as a search term.
- -q nn
- Quiet mode. Only prints every nn status reports.
Specify -1 for no status.
- The scan_wordlist scanner should only extract words that are
between n1 and n2 characters in length.
The following commands are useful for debugging:
- -C NN
- Specifies the size of the context window.
- -S fr:<name>:window=NN
- specifies context window for recorder <name> to NN.
- -S fr:<name>:window_before=NN
- specifies context window after to NN for recorder <name>
- -S fr:<name>:window_after=NN
- specifies context window before to NN for recorder <name>
- -G NN
- specify the page size
- -g NN
- Specifies the size of the margin in bytes.
- -j NN
- Use n threads for analysis. Normally you do not need specify this,
as the default is the number of processors on the current computer.
- -m NN
- Have bulk_extractor wait at most NN minutes for scanners to finish
after all data have been read.
Finally, you can control scanners with these options:
- Print the version number
- -R outdir
- Restarts the program from where it left off for a particular directory.
- -B nn
- Set the dedup Bloom filter to nn bits. This is used by the
- -M nn
- Specifies a maximum recursion depth of nn.
- -z pagenum
- Start on page number pagenum.
- -Y <o1>[-<o2>]
- Start at input offset o1 optionally ending at offset o2
- Enable debugging level N.
bulk_extractor is based on a feature extractor and named entity
recognizer developed for SBook in 1991. The feature extractor was repurposed
for disk images in 2003. The stand-alone bulk_extractor program was
rewritten in 2005 and publicly released in 2007. The multi-threaded
bulk_extractor was released in May 2010.
Simson Garfinkel <firstname.lastname@example.org>
- -P <dir>
- Specifies a directory in which to find plugins.
- -E scanner
- Turns off all scanners, then enabled scanner scanner.
- -e scanner
- Enables a scanner.
- -x scanner
- Disables a scanner.