cool idea about the hex editor. I didn't even think of that.
As far as generating a dictionary of possible password, that would require
about 10828567056280801 possible passwords in a dictionary. That is a huge
file and would be very large in respect to hard drive space. Not saying it
couldn't be done, but I wouldn't want to do it.
Ken
-----Original Message-----
From:
[mailto:]On Behalf Of Ingecom - SERRE
Jean-Christophe
Sent: Wednesday, August 16, 2000 3:17 PM
To:
Subject: RE: Brute force VNC crack
"Kenneth Foster" <> wrote:
>
> brute forcing of passwords will always work. There are two ways to do
stop
> this.
>
> 1: Use passwords that don't show up in dictionaries. This may be
more
> difficult to remember, but it makes it less likely to be cracked. The
code,
> as written, uses a dictionary attack. Not quite what it says in the title
> of the crack.
Yes and no: in "hacker toolz" you'll find a lot of little programs for
generating you a (huge) textfile with the complete list of possible
passwords based on your provided character set and mini/maxi lengths --
then, using that textfile as the "dictionnary" will actually perform the
brute-force attack.
This kind of attack tool often just provide support for an external
textfile, because it allows to reuse the wealth of available
dictionnaries as well as a brute-force generated textfile, while being a
simple quick-n-dirty program...
> 2: The other way to stop this is to change the encryption key used by
your
> company and recompile your server and client tools. By changing the key
no
> password, even the correct one, from a non-company VNCviewer will work. At
> least from my testing.
As a note, since most people don't have VC++6 or time for recompiling
VNC, this can also be easily done, as always, by a mere hex-patch.
>From the WinVNC source file "vncauth.c" we see that VNC's DES key is:
unsigned char fixedkey[8] = {23,82,107,6,35,78,88,7};
which is, in hex:
17 52 6B 06 23 4E 58 07
Using any hex-editor, one will find a unique occurence of that hex
pattern in the WINVNC.EXE and VNCVIEWER.EXE binaries, and will be able
to hex-change it for a custom key w/o any recompilation.
-- JCS - Jean-Christophe SERRE - INGECOM France - +33 (0)1.48.34.12.34Microsoft: the 51st State of America -- 52nd coming soon! --------------------------------------------------------------------- To unsubscribe, send a message with the line: unsubscribe vnc-list to See also: --------------------------------------------------------------------- --------------------------------------------------------------------- To unsubscribe, send a message with the line: unsubscribe vnc-list to See also: ---------------------------------------------------------------------
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This archive was generated by : Wed Aug 16 2000 - 17:55:40 EDT