About:
Lepton's Crack is a generic password cracker. It is easily-customizable with a simple plugin system and allows system administrators to review the quality of the passwords being used on their systems. It can perform a dictionary-based (wordlist) attack as well as a brute force (incremental) password scan, including the use of regular expressions. It supports standard MD4 hash, standard MD5 hash, NT MD4/Unicode, Lotus Domino HTTP password (R4), and SHA-1 hash formats. LM (LAN Manager) plus appending and prepending of characters is available in the Development branch (strongly recommended).

Release focus: Major feature enhancements

Changes:
REGEX enumeration when len is greater than 1 now starts with len=1 and proceeds up to max_len. Charset and REGEXes can now be saved to a text file. -stdin allows feeding lcrack from an external password generator. The mktbl program is now included to generate pre-computed hash tables (rainbow tables). LM hsa been briefly deactivated until the next version to rework it.

Author:
Lepton and Nekromancer <lcrack (at) eudoramail (dot) com> [contact developer]

Rating:	reset 1 2 3 4 5 6 7 8 9 10
8.60/10.00 (49 votes)

Homepage:
http://usuarios.lycos.es/reinob/
Tar/GZ:
http://usuarios.lycos.es/reinob/lcrack/lcrack-20040914.tar.gz
Changelog:
http://usuarios.lycos.es/reinob/lcrack/CHANGES

Trove categories: [change]

[Development Status]		5 - Production/Stable
[Environment]		Console (Text Based)
[Intended Audience]		System Administrators
[License]		OSI Approved :: GNU General Public License (GPL)
[Operating System]		Microsoft :: Windows :: Windows NT/2000/XP, Other OS, POSIX :: Linux
[Programming Language]		C
[Topic]		Security, Security :: Cryptography, System :: Systems Administration, Utilities

Dependencies: [change]
No dependencies filed

 Branches

Branch	Version	Last release	License	URLs
Default	20040914	17-Sep-2004	GNU General Public License (GPL)

 Releases

Version	Focus	Date
20040914	Major feature enhancements	17-Sep-2004 13:49
1.1	Major feature enhancements	06-Jan-2003 10:14
1.0.1	Minor bugfixes	18-Dec-2002 14:24
1.0	Initial freshmeat announcement	17-Dec-2002 22:44

 Comments

[»] Mingw support
by Bernardo Reino (Lepton) - Sep 2nd 2004 16:10:08

I've done a couple of changes in sha1.h, md5.c solving some compatibility problems.

Also, LCrack can now be compiled under the MINGW environment (gettimeofday() is now implemented for MingW, and %llu is replaced by %I64u -- don't worry, it's all #ifdef'd, so Unix/Linux/Cygwin works like always..)

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[»] Improvements and new features..
by Bernardo Reino (Lepton) - Sep 2nd 2004 12:55:10

Hi all,

After a long time, I'm back with lcrack :)

The regex's are now enumerated in increasing-length order, and the speed penalty is very small (if you prefer the 'old' way of enumerating regex's, use the '-g#' switch instead of '-g')

I've also added a separate 'regex' program that enumerates the expression (with the 'usual' -s, -l and -g[#]) and dumps it to stdout..

I'm now also making a program called 'mktbl' that generates pre-computed tables for faster cracking. Input is stdin (one word per line), and output is a binary file suitable for use with '-xf+ -t' in lcrack. The program is already finished, but I'm testing it..

I still haven't integrated my version with Bruneti's improvements, but hopefully I'll take care of that soon..

I will shortly update the lycos site and the stuff here..

Lepton.

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[»] Hi from Argentina!!!!!
by Lord Cheseline - Aug 11th 2004 01:55:33

Hello Mike!

Wonderful to see that you are still active with the tool.
Greetings from one of your students @CIUA!
CU

Lord Cheseline
aka Umpy ;-)

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[»] Re: Hi from Argentina!!!!!
by Nekromancer - Aug 11th 2004 02:36:51

Hi Umpy Nice to "see" you here ;-) Are you "still in the business"? email me privately please. Cheers, Nekromancer

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[»] Can you make it faster?
by Erman - Aug 11th 2004 01:19:09

I regularly use John The Ripper, mainly because is 8 times faster than lcrack, but it lacks regex and sha-1 support.

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[»] Re: Can you make it faster?
by Nekromancer - Aug 11th 2004 02:35:44

Hi Erman, I ALSO use John the Ripper when bruteforce cracking speed or password mangling is a must ;-) I use Lepton's Crack for the features that make it unique: a) REGEX support (see the link to the demo above) b) Lotus Domino R4 support c) SHA-1 support Answering your question, the code is almost as fast as possible using pure C language (OK, someone can improve it, for sure ;-) To make it faster, portions of it have to be coded in machine language, thus losing portability, and it's definitely not our intention to do that in the inmediate future. Cheers, Nekromancer

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[»] About the use of wildcards in the REGEX functionality
by Nekromancer - Aug 10th 2004 03:52:02

Well... I don't know if some people discovered that, but we never mentioned this in the documentation ;-)
Lepton's Crack 20030404 and newer HAS wildcard support in the REGEX functionality, that allows variable length support.
In this case, the -l modifier (normally used to specify the maximum length to try for the entire password) has a slightly different meaning. It specifies the length of the variable (wildcard) section.

Example:

For some strange reason, I know that a password starts with sjk (not sure about the case), but I'm not sure what come after that or how many keys were pressed, and it ends with 56.

./lcrack -m nt4 -g [sS][jJ][kK][*][5][6] -xb+ -l 4 crackme.txt

This will scan passwords with up to 4 characters in the wildcard position.

./lcrack -m nt4 -g [sS][jJ][kK][*][5][6] -xb+ -l 8 crackme.txt

This will scan passwords with up to 8 characters in the wildcard position, and will take loooong.
All other characters will follow the standard REGEX rules:
1st character: s or S
2nd character: j or J
3rd character: k or K
last 2 characters: 56

The reason it will take long in the second example is because currently lcrack starts testing with the longest string, and proceeds down to 1 character.
That means that:
a) we've to change the routine to start with the shortest string, and proceed up to the longest
b) in the mean time, it's better for you if you start with a short string, and if there's no match try a longer one, sorry!

Cheers,

Nekromancer

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[»] Crack mode in latest development branch (20031130)
by Nekromancer - Jul 30th 2004 05:44:14

Piero changed the default crack mode to NONE in engine.c
That means that you HAVE to specify at least 1 cracking mode with:
-xl+ : login mode
-xf+ : fast word list mode
-xs+ : smart word list mode
-xb+ : brute-force mode

Of course you can specify more than one (example):

./lcrack -m dom -xl+ -xb+ hashes.txt

will try login mode first, then incremental (bruteforce).

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[»] Solving compiling problems with gcc 3.x
by Nekromancer - Jul 30th 2004 05:39:19

As mentioned in Lepton's Crack original site (http://usuarios.lycos.es/reinob/):

If you run into problems trying to compile it with gcc 3.x, modify the file sha1.h as follows (i.e.: remove the old code, put in the new one):

OLD CODE:
#ifdef __USE_ISOC99
#include <stdint.h>
#else
/*
* If you do not have the ISO standard
* stdint.h header file, then you
* must typdef the following:
* name meaning
* uint32_t unsigned 32 bit integer
* uint8_t unsigned 8 bit integer (i.e., unsigned char)
* int_least16_t integer of >= 16 bits
*
*/
typedef unsigned int uint32_t;
typedef unsigned char uint8_t;
typedef short int int_least16_t;
#endif

NEW CODE THAT WORKS:
#include <stdint.h>

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[»] CLUSTER
by Gordon - Jul 23rd 2004 03:53:59

Can this program be clustered?

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[»] Re: CLUSTER
by Nekromancer - Jul 23rd 2004 04:23:57

Hi Gordon, The application itself doesn't contemplate clustering, but I did some testing using clusterKnoppix and splitting the file with the hashes in as many parts as nodes I had in the cluster. With this setup, clusterKnoppix itself took care to migrate every instance of lcrack into a sepparate node, and all of them run at full speed. In my opinion is the best way to "clusterize" Lepton's Crack. Cheers, Nekromancer

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[»] New version with LM support, appending and prepending, etc.
by Nekromancer - Jul 22nd 2004 07:59:33

All this can be found in the latest and greatest in Piero Brunati's website at:
http://www.nestonline.com/lcrack/

I strongly suggest that everyone interested in the use of the REGEX functionality (probably the most interesting one in Lepton's Crack) has to read the paper "An Experiment with Lepton's Crack" by Piero Brunati:
http://www.nestonline.com/lcrack/lcexp1.html

Finally, for the clickies, enjoy the frontend programmed by Matteo Brunati:
http://www.nestonline.com/lcrack/lcFE.htm

Cheers!

Nekromancer

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[»] The development continues...
by Nekromancer - Apr 14th 2004 05:48:47

But now is in the hands of Piero Brunati and his son Matteo.
They've implemented the cracking of non-visible characters in LM hashes (in fact the whole character set 0-255), wrote some nice documentation, and a very good graphical frontend.
Thanks Piero and Matteo!

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[»] Testing REGEX on development version
by Nekromancer - Apr 22nd 2003 01:43:55

I'm testing this functionality, but of course we'll be very happy to receive information about any errors in the development version in the email specified in the README.Developers ;-)

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[»] Re: Testing REGEX on development version
by Ernie Hammond - Jun 6th 2003 07:38:36

Has been using it for a while without a glitch.

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[»] Suggestion for TODO list
by Nube9 - Jan 21st 2003 01:11:22

The program is just excellent, but I'll love if it has some "resume" functionality to stop the cracking and continue later.

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[»] Re: Suggestion for TODO list
by Nekromancer - Jan 21st 2003 04:46:43

Well... this is in an unwritten TODO list ;-)

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[»] Congratulations
by RockDaHouse - Jan 14th 2003 00:47:03

K00l guys. Keep adding more modules. This program is wonderful.

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[»] Re: Congratulations
by DarkZide - Jan 14th 2003 06:51:37

Perhaps it would be better if we try to help... it's Open Source, isn't it? ;-D

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[»] Re: Congratulations
by Nekromancer - Jan 14th 2003 10:22:19

Yes, it's Open Source under GPL. And all of us around the world can help to make this program as powerful and useful as we want. Thanks for the comments!

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[»] Developers are welcomed
by Nekromancer - Jan 7th 2003 08:27:45

Specially if anyone is willing to create a "standard" configure script that uses autoconf and the like ;-)
Thank you in advance!

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[»] Update
by Bernardo Reino (Lepton) - Dec 30th 2002 16:58:42

Support for SHA-1 hashes has been added, thanks to
a patch contributed by Burcin Erocal.

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