Crack 5.0 -- does it handle password diffs automatically?

Crack 5.0 -- does it handle password diffs automatically?

Post by Ben Bolke » Wed, 04 Mar 1998 04:00:00



I have a question, I hope not too boneheaded, about Crack 5.0a--I
have looked through docs and source, haven't found the answer, may have
missed it.

   Does Crack automatically ignore previously *tested*
(not previously *cracked*) passwords?  On our network, the password
file changes relatively slowly and Crack takes a long time to complete;
it's only actually finished once in the last few months (because
the machine goes down or the job gets interrupted for some other
reason).  If I only run Crack on passwords that have changed since
the last Crack run started, I can save a lot of time.  As far as I can
tell from examining past runs, Crack *doesn't* do this by default.

  It's quite straightforward to write the scripts to do this -- I've
already done it -- but I don't want to mess with this if there is a
built-in way to make Crack do it, since it will probably do it more
carefully than I have.  Or is there any reason (can't think of one) that
it isn't worth doing?

  thanks,
      Ben

--
Benjamin Bolker          Dep't of Ecology and Evolutionary Biology,

tel: (609) 258-6886,     fax: (609) 258-1334

 
 
 

Crack 5.0 -- does it handle password diffs automatically?

Post by Alec Muffet » Thu, 05 Mar 1998 04:00:00



>Does Crack automatically ignore previously *tested*
> (not previously *cracked*) passwords?

No.

Version 4.1 used to do this, but the functionality was removed in 5.0
due to the reworking of what is/is not stored in the output files.
I am working on re-instating it in the next version.

In the meantime, I suggest examination of the possibilities "sort" and
"comm" may yield to you... you're correct, it's only an extra 3..4
lines of code to do it external to the rest of Crack.

        - alec
--
# *** direct e-mail replies to the sender by replacing "ZZ" with "CO" ***
#   alec muffett, oxford, uk - http://www.users.dircon.co.uk/~crypto/
#  below: password cracker in one line of perl; echo guess | perl [args]
 perl -nle 'setpwent;crypt($_,$c)eq$c&&print"$u=$_"while($u,$c)=getpwent'

 
 
 

Crack 5.0 -- does it handle password diffs automatically?

Post by Daniel Eisenb » Sat, 14 Mar 1998 04:00:00





>>Does Crack automatically ignore previously *tested*
>> (not previously *cracked*) passwords?

>No.

>Version 4.1 used to do this, but the functionality was removed in 5.0
>due to the reworking of what is/is not stored in the output files.
>I am working on re-instating it in the next version.

>In the meantime, I suggest examination of the possibilities "sort" and
>"comm" may yield to you... you're correct, it's only an extra 3..4
>lines of code to do it external to the rest of Crack.

I use this trick, and it works quite well.  But one reason that I wish
it were integrated into Crack is that I would generally want Crack to do
a gecos run from the whole password file's GECOS on the whole password
file each time, at least if any of the GECOS info has changed.  Right
now I just do an extra GECOS run on the whole file, commenting out the
other dictionaries, once in a while, but this is unwieldy.

Also, I am not sure about this, but I get the feeling that even once
crack has cracked a password during a run, it will keep trying the rest
of the dictionary against that word.  If this is the case, it slows down
runs where one gets a lot of the password file on the group 1
dictionaries, significantly.  But maybe I'm mistaken in this impression?

-Daniel Eisenbud

--
Daniel Eisenbud

 
 
 

Crack 5.0 -- does it handle password diffs automatically?

Post by Alec Muffet » Sun, 15 Mar 1998 04:00:00



> I would generally want Crack to do
> a gecos run from the whole password file's GECOS on the whole password
> file each time, at least if any of the GECOS info has changed.

Ahhhhh... subtle.  Just in case someone's girlfriend gets an account
between runs, you mean?

Quote:> Also, I am not sure about this, but I get the feeling that even once
> crack has cracked a password during a run, it will keep trying the rest
> of the dictionary against that word.

Nope.  The ciphertext gets cookie nulled out and is not checked further.

AFAICR, TI.  i8-)

--
# *** direct e-mail replies to the sender by replacing "ZZ" with "CO" ***
#   alec muffett, oxford, uk - http://www.users.dircon.co.uk/~crypto/
#  below: password cracker in one line of perl; echo guess | perl [args]
 perl -nle 'setpwent;crypt($_,$c)eq$c&&print"$u=$_"while($u,$c)=getpwent'

 
 
 

1. uncracked passwords processing in Crack 5.0

Hi,

the previous version of Crack (v4) had a possibility of including
noncrackable passwrods in F.merged file. This meant thet if Crack has
finished and it didn't crack some passwords, they were presumed uncrackable,
at least for the specific dictionaries and rules set. Very good - next run of
Crack was warking only on new/changed passwords.

I've just installed Crack v5.0, run it about a week on my ~300 users passwd
file. After it finished and I made "make tidy" I run Crack on the actual
passwd file (some users could change their passwords meanwhile). And what had
happened? Crack started to break all passwords (except those cracked in the
previous run). As far as I didn't add any dictionary and/or rule, it makes no
sense - Crack will NOT break these passwords by any way. So why should I wait
another week instead of waiting one day for braking 3 passwords that have
been changed since last Crack run?

Does anybody have any idea how to automagically include uncrackable passwords
in the F-merged file ?

                                        TIA, Grzesiek
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