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Re: shell:windows command question
From: Barry Fitzgerald <bkfsec () sdf lonestar org>
Date: Wed, 07 Jul 2004 17:13:03 -0400

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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