From: sandblad at acc.umu.se (Andreas Sandblad)
Subject: shell:windows command question

Did some quick search on Bugzilla and came up with the following:

Mozilla allows external protocols as discussed in:
http://bugzilla.mozilla.org/show_bug.cgi?id=167475
They seem to blacklist the following external protocol handlers:
(patch http://bugzilla.mozilla.org/attachment.cgi?id=102263&action=view)
hcp, vbscript, javascript, ms-help, vnd.ms.radio

A simple solution would be to add the shell protocol to this list.
Personally I think a secure blacklist is hard to maintain as new
dangerous external protocols could be invented by third-parties leaving
Mozilla vulnerable again.

/Andreas Sandblad

On Thu, 8 Jul 2004, Andreas Sandblad wrote:

> It doesn't seem to affect Windows 2000, only Windows XP.
> This is a fault in Mozilla. Why? Because it allows access to a dangerous
> protocol from within a non local resource. The Mozilla project should fix
> this before anyone creates an exploit to run arbitrary code.
>
> Personally I think the shell: issue should have been reported to the
> Mozilla security team before publiced to the masses.
>
> /Andreas Sandblad
>
> On Wed, 7 Jul 2004, Barry Fitzgerald wrote:
>
> > I just verified this in Mozilla 1.7 on Windows XP pro.
> >
> > (I know -- no reason why it shouldn't work on 1.7 if it worked on firefox)
> >
> > In any case, it does appear to be an issue with MS Windows and not
> > Mozilla, but the Mozilla project should still, IMO, filter out the
> > shell: scheme type and other dangerous (but essentially useless on the
> > web) scheme types identified in MS Windows.  In fact, they should filter
> > all out accept for accepted scheme types.  Default-closed as opposed to
> > default-open.
> >
> >              -Barry
> >
> >
> > Andreas Sandblad wrote:
> >
> > >This is dangerous. Based on the file extension of the shell protocol
> > >different applications may be launched. For example:
> > >shell:.its will launch Internet Explorer
> > >and shell:.mp3 will launch Winamp.
> > >
> > >The trick is to find an application that will overflow when given a
> > >very long parameter. A quick check showed that a buffer overflow occured
> > >within MSProgramGroup (WINDOWS\System32\grpconv.exe) after around 230
> > >bytes with the following URL:
> > >shell:[x*221].grp
> > >EIP can be controled, but exploitation is a bit tricky since parameter is
> > >stored as unicode.
> > >
> > >Also Winamp contains an BO (no unicode here).
> > >
> > >Tested environment:
> > >Windows XP pro + FireFox 0.9.1
> > >
> > >/Andreas Sandblad
> > >
> > >On Wed, 7 Jul 2004, Perrymon, Josh L. wrote:
> > >
> > >
> > >
> > >>-----snip------
> > >>center><br><br><img src="nocigar.gif"></center>
> > >><center>
> > >><a href="shell:windows\snakeoil.txt">who goes there</a></center> <iframe
> > >>src="http://windowsupdate.microsoft.com%2F.http-
> > >>equiv.dyndns.org/~http-equiv/b*llsh*t.html" style="display:none">
> > >>[customise as you see fit]
> > >><http://www.malware.com/stockpump.html>
> > >>------end----------
> > >>The code above has interest to me.
> > >>Even in Mozilla the commands below will work.
> > >><a href=shell:windows\\system32\\calc.exe>1</a>
> > >><a href=shell:windows\system32\calc.exe>2</a>
> > >><a href=shell:windows\system32\winver.exe>4</a>
> > >>Just save them to an .html file and run it.
> > >>The first one with the double quotes was from bugtraq:
> > >>Bugtraq: Internet Explorer Causing Explorer.exe - Null Pointer Crash
> > >><http://seclists.org/lists/bugtraq/2004/Mar/0188.html>
> > >>The links below that will run calc as well as winver.
> > >>It seems it calls windows as a virtual dir because c:\winxp is what I have.
> > >>I have been playing around to see if cmd.exe will work with it but without
> > >>luck.
> > >>This is what is in the registry.
> > >>HKEY_CLASSES_ROOT\Shell
> > >>Look in the registry key above. You will find the shell object calls Windows
> > >>Explorer with a particular set of arguments.
> > >>%SystemRoot%\Explorer.exe /e,/idlist,%I,%L
> > >>So this is tied to explorer.exe. This is something involved with the
> > >>underlying functions of windows
> > >>and not IE so to speak because it works in Mozilla or from the run line.
> > >>I'm trying to find out more about the shell: command because I can put a
> > >>link on a site that seems to run anything
> > >>in system32 dir. I'd like to see if you can pass parameters to it.
> > >>
> > >>Anyone give me more info on the shell:windows command?
> > >>JP
> > >>
> > >>
> > >>Joshua Perrymon
> > >>Sr. Network Security Consultant
> > >>PGP Fingerprint
> > >>51B8 01AC E58B 9BFE D57D  8EF6 C0B2 DECF EC20 6021
> > >>
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-- 
      _     _
    o' \,=./ `o
       (o o)
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 Andreas Sandblad
 Ume?, Sweden

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