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Message-ID: <CA+TsHUAxRN4MjQxvxJGm0=6eRjTNFubsrks7PzvsM6QfyzQ0mw@mail.gmail.com>
Date: Tue, 26 Jun 2012 07:47:39 +0530
From: SAYANTAN DATTA <std2048@...il.com>
To: john-dev@...ts.openwall.com
Subject: Re: Jumbo candidate vs Test Suite
On Mon, Jun 25, 2012 at 9:49 AM, jfoug <jfoug@....net> wrote:
> Could this be buffer overwrites, smashing passwords? The TS was written
> specifically to cause this form of corruption on formats which require
> additional sanity checking, prior to copying passwords.
>
> If you look at the pw.dic file (and others???) there will be some bugus,
> unused lines that are long. These are on purpose, and they have flushed
> out
> overwrite issues in many of the jumbo formats.
>
> This often shows up, if you have a format, where there is an array of
> candidates worked on at the same time, and these are interspersed (such as
> SSE), and part of the input buffer is not written to, because it is not
> supposed to ever be modified. Then, if an overlong password is copied into
> this buffer, and is longer than it should be, and overflows, then that
> array
> element (and possibly OTHERS), will never find a password again, for the
> rest of the run.
>
> When magnum and I were working through a lot of the formats, and designing
> the TS, we built it this way, and shook out a LOT of bugs. What you are
> listing for numbers IS in the range we were used to seeing (40 to 60%
> found,
> out of the 1500).
>
> The work around for this, was determining just WHAT the max number of bytes
> that can be in a password for your format, and making damn sure that you
> truncate any password input line longer than this, to that many bytes, so
> as
> to NEVER overflow your pristine buffers.
>
> I do not know if this is the issue, but from experience, it sounds like it
> 'could' be. IF this IS the case, then the TS is 100% valid, in flushing
> the bug out, it IS a bug. You will have users that use 'dirty' wordlists,
> which contain some pretty long lines. If you do not properly limit and
> protect your format, these dirty input files WILL cause passwords to be
> missed.
>
> Jim.
>
> >From: Lukas Odzioba [mailto:lukas.odzioba@...il.com]
> >
> >2012/6/25 Solar Designer <solar@...nwall.com>:
> >> Do you have an idea of what the remaining problem is?
> >
> >If I had to guess: UTF, Unicode, salt/pass length.
>
>
Yeah, mscash2-opencl guessed 1410 times only after I reduced the plaintext
length to 31 from 40 . I couldn't understand this at first but now it is
clear.
Regards,
Sayantan
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