PASSWORD GUESSING

[Jim McCoy]

In article <737 at rwing.UUCP> pat at rwing.UUCP (Pat Myrto) writes:
>In article <1919 at aucs.UUCP>, 861087p at aucs.UUCP (A N D R E A S) writes:
>> 
>>    
>>        A long time ago someone posted a program that did password
>> guessing using the Unix dictionary and the /etc/passwd file.
>> Can someone mail me the progra? 
>> Please don't post it in the list.
> 
>Your account name and .signature doesn't indicate that you have any
>special needs, (like being a sysad, or user responsible for system
>security) and none are stated in your posting.  What would you
>want with a password cracking program anyway - I think that due to the
>nature of your request, a reason would be appropriate.  No, I don't
>have a copy of what you ask for - just making an observation.
>

	Gimme a break!  It may come as a shock, but some people who
ARE sysads (like me) don't post or use trivial programs when we are
root.  Besides, a password cracker is not a difficult program to make,
and is generally considered a rite of passage at some places ( like
here :-).  First, it should be obvious that a "password cracker" will
only get the most obvious and insecure passwords.  When we do a check
of security around here (about once every three months or so) we
usually let this beast run for a day or two on a machine with no one
else logged in, so if you are trying to "hack the system"  this is not
the reccommended method unless your sysads won't notice a program that
runs for a day and eats up almost all CPU time.
	While i won't post this program out of the paranoid fear some
people may have, I will give a general overview that any sysad should
be able to code (or have someone else code for him ;-).

	1)  Look at the crypt call (man3 i think), the format that the
passwd file uses is [salt-2 chars][passwd-11 chars].

	2)  Make repeated calls to crypt using the salt in passwd and
the words in /usr/dict/words plus things like user name and GECOS
info.

	3)  This should make a resonable check for stupid passwords
that some people use.

	BTW,  If you are looking to set up a more secure passwd
scheme, look into shadow password files, and changing the passwd
program to not accept any entries that the above would find (i have
the modified code if you want it, it will also generate secure
passwords that are fairly easy to remember).


>-- 
>pat at rwing     ...!nwnexus!mltco!camco!happym!\      (Pat Myrto),  Seattle, WA
>                          ...!uunet!pilchuck!rwing!pat
>                  ...!uw-beaver!sumax!polari!/
>WISDOM:    "Travelling unarmed is like boating without a life jacket" 


					jim

------------------------------< Jim McCoy >------------------------------------
mccoy at acns.nwu.edu                  |  "...far too many notes for my taste"
#include <disclaimer.h>             |        -Phantom of the Opera
			"To thine own self be true"