Crunch is a tool for creating wordlist, which can be used to bruteforce or audit password strength. However crunch can use patterns to reduce wordlists sizes, can compress output files in various formats and now includes a message showing size of the wordlists that will be created, you can cancel the creating of wordlist by pressing “CTRL” C in Windows “COMMAND” C on Mac.
Whey to create wordlist using crunch?
Crunch can be used to build custom wordlist, hackers use that tool to create targeted wordlist for there victims and brute force their passwords. You can create custom wordlist using crunch to break into someone’s wifi password if you have collected some information using social engineering.
How to install Crunch?
Crunch comes pre-installed in Kali Linux and for windows you can download this tool.
If your own Linux you can simply
apt-get install crunch.
Create Wordlist Using Crunch Video:
The full range of options is as follows
-b Maximum bytes to write per file, so using this option the wordlist to be created can be split into various
sizes such as KB / MB / GB (must be used in combination with “-o START” switch)
-c Number of lines to write to output file, must be used together with “-o START”
-d Limits the number of consecutive identical characters (crunch v3.2)
-e Specifies when crunch should stop early (crunch v3.1)
-f Path to the charset.lst file to use, standard location is ‘/pentest/passwords/crunch/charset.lst
to be used in conjunction with the name of the desired charset list, such as ‘mixalpha-numeric-space’
-i Inverts the output sequence from left-to-right to right-to-left
(So instead of aaa, aab, aac, aad etc, output would be aaa baa caa daa)
-l When specifying custom patterns with the -t option, the -l switch allows you to identify which of the characters
should be taken as a literal character instead of a place holder ( @,%^ )
-o Allows you to specify the file name / location for the output, e.g. /media/flashdrive/wordlist.txt
-p Prints permutations of the words or characters provided in the command line.
-q Prints permutation of the words or characters found in a specified file
-r Resumes from a previous session, exact same syntax to be used followed by -r
-s Allows you to specify the starting string for your wordlist.
-t Allows you to specify a specific pattern to use. Probably one of the most important functions !
Place holders for fixed character sets are ;
@ — lower case alpha characters
, — upper case alpha characters
% — numeric characters
^ — special characters (including space)
-u Supresses the output of wordlist size & linecount prior starting wordlist generation.
-z Adds support to compress the generation output, supports gzip, bzip & lzma
BASIC USAGE AND CHARACTER SETS
Make your own custom wordlist using crunch:
The default installation directory in Kali Linux for crunch is: /usr/bin/crunch and you can find crunch charset.txt inside /usr/share/crunch/ directory.
Basic Usage of Crunch:
crunch <min> <max> [option]
Also any desired character set can be enterered manually in the command line ;
crunch 6 6 0123456789ABCDEF
Certain characters will need escaping with a backslash \ ;
Creating Wordlist in Certain Size:
Using the -b switch, we can tell crunch to create a wordlist which is split into multiple files
of user-specified sizes.
This must be done in conjunction with -o START.
The size definition can be; kb, mb, gb or kib, mib, gib
kb, mb, and gb are based on the power of 10 (i.e. 1KB = 1000 bytes)
kib, mib, and gib are based on the power of 2 (i.e. 1KB = 1024 bytes).
The output files will be named after the first and last entry in the wordlists.
To create a wordlist split into files of not more than 1mb;
Creating Wordlists in Blocks of certain Linecount:
(ie. number of passphrases per file)
Using the -c switch you can have crunch create wordlists which do not contain more than the
specified number of lines.
This must be used in conjunction with -o START.
To create files containing no more than 200000 (200 thousand) lines (passphrases);
crunch 6 6 0123456789 -c 200 -o START
Stopping Crunch Wordlist at Pre-determined time:
crunch 6 6 -t %%%%%% -e 333333
Using Fixed Charset.txt in Crunch:
crunch 6 6 -f /usr/share/crunch/charset.lst ualpha -o START
There’s ton more charsets inside /usr/share/crunch/charset.lst
Inverting the output direction in crunch:
Using the –i option will invert the direction in which the wordlist is created, from left-to-right to right-to-left.
Note that this does not change the content of the created wordlist, it only changes the intial direction in which it is created.
Creating Permutations in Crunch:
Crunch can also be used to create permutations for either ;
> characters / words entered in the command line with the -p switch.
> lines in a wordlist with the -q switch
Although there is no min/max character setting, this still needs to be entered for both
the -p and -q switch.
Using the -p switch you can create permutations of characters or of all words entered in the command line.
Creating permutations of letters (fun for anograms) ;