How to find lost ZIP file passwords with "fcrackzip"
fcrackzip is a free ZIP password cracking utility for Linux and OS X that can be used to recover lost ZIP file passwords through brute force or dictionary attacks.
To install fcrackzip on Linux, you can use use apt-get:
sudo apt-get install fcrackzip
... yum:
sudo yum install fcrackzip
... or a similar repository system.
To install fcrackzip on Mac OS X, first install MacPorts then install fcrackzip through MacPorts:
sudo port install fcrackzip
The default brute force starting length is 5-6 characters, so you might want to specify a minimum and maximum password length when you invoke fcrackzip. To use the utility, switch to the directory containing your encrypted ZIP file and run fcrackzip with the "-b" (use a brute force attack), "-u" (use unzip to weed out wrong passwords), and "-l" (specify password length) arguments:
fcrackzip -b -u -l 1-4 geekology.zip
The software will run for some time depending on the complexity of the ZIP file's password and will display a success message once it finds the correct key (in my test the brute force attack took 1 minute to find the correct result for a 4-letter password):
PASSWORD FOUND!!!!: pw == geek
You can find more information on fcrackzip's usage in its help page ("fcrackzip -h"):
fcrackzip version 1.0, a fast/free zip password cracker
written by Marc Lehmann
You can find more info on
http://www.goof.com/pcg/marc/
USAGE: fcrackzip
[-b|--brute-force] use brute force algorithm
[-D|--dictionary] use a dictionary
[-B|--benchmark] execute a small benchmark
[-c|--charset characterset] use characters from charset
[-h|--help] show this message
[--version] show the version of this program
[-V|--validate] sanity-check the algortihm
[-v|--verbose] be more verbose
[-p|--init-password string] use string as initial password/file
[-l|--length min-max] check password with length min to max
[-u|--use-unzip] use unzip to weed out wrong passwords
[-m|--method num] use method number "num" (see below)
[-2|--modulo r/m] only calculcate 1/m of the password
file... the zipfiles to crack
methods compiled in (* = default):
0: cpmask
1: zip1
*2: zip2, USE_MULT_TAB
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