Re: [FDSA] Sort - Critical Format StringVulnerability

["Larry Seltzer" <Larry () larryseltzer com>]

> > This vulnerability allows for arbitrary command execution and is really quite severe.  

So the following proof of concept causes the Windows Calculator to be executed?

C:\>calc

Larry Seltzer
eWEEK.com Security Center Editor
http://security.eweek.com/
http://blogs.pcmag.com/securitywatch/
Contributing Editor, PC Magazine
larry.seltzer () ziffdavisenterprise com


-----Original Message-----
From: full-disclosure-bounces () lists grok org uk [mailto:full-disclosure-bounces () lists grok org uk] On Behalf Of 
Fredrick Diggle
Sent: Friday, January 18, 2008 9:06 AM
To: Tonnerre Lombard
Cc: full-disclosure () lists grok org uk
Subject: Re: [Full-disclosure] [FDSA] Sort - Critical Format StringVulnerability

Fredrick Diggle apologizes, he always forgets that exploitation is IMPOSSIBLE if there is no how-to in phrack. Racing 
your own buffer is hard Lombard so he feels your pain :(

Also how dare you accuse Diggle Sec of releasing fake vulnerabilities.
Continue down that train of thought and you are likely to find yourself in a lawsuit sir.

Also we noted your comment about pipes and performed further analysis.
What we discovered was shocking! You are indeed correct that the published proof of concept inadvertently exploits a 
previously unpublished vulnerability it the windows command line utility. This vulnerability allows for arbitrary 
command execution and is really quite severe. We will be happy to credit you with its discovery.

On Jan 18, 2008 1:45 AM, Tonnerre Lombard <tonnerre.lombard () sygroup ch> wrote:
> Salut, Fredrick,
>
> On Thu, 17 Jan 2008 12:05:13 -0600 "Fredrick Diggle"
> <fdiggle () gmail com> wrote:
> > The following output shows a manafestation of this vulnerability:
> >
> > C:\>sort AAAA%x.%x.%x.%x
> > AAAA7c812f39.0.0.41414141The system cannot find the file specified.
>
> This is actually confirmed on Windows 2000 and XP.
>
> > This vulnerability can be trivially exploited to execute arbitrary 
> > code on the computer machine.
>
> There I don't agree however, it is a simple memory reading 
> vulnerability.
>
> > The following command line will use sort.exe to execute the windows 
> > calculator.
> >
> > C:\>sort CALC.EXE%x%x%x%n | calc
>
> That's not very surprising since you pipe into the calculator so it is 
> spawned by the shell.
>
> > Severity: Quite High
>
> There I don't agree. In theory, there should not be anything important 
> in the memory of the sort process which is not already known to the 
> user executing it anyway. It is clearly a bug though, and wants to be 
> fixed. So congratulations to a working, though overdramatizised, 
> discovered format string vulnerability.
>
>                                 Tonnerre
> --
> SyGroup GmbH
> Tonnerre Lombard
>
> Solutions Systematiques
> Tel:+41 61 333 80 33            Güterstrasse 86
> Fax:+41 61 383 14 67            4053 Basel
> Web:www.sygroup.ch              tonnerre.lombard () sygroup ch

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_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/