FW: Windows Update - Unsafe ActiveX control (fwd)

[Dave Ahmad]

---------- Forwarded message ----------
Date: Thu, 17 Jul 2003 XX:XX:XX
To: Dave Ahmad <da@securityfocus.com>
Subject: FW: Windows Update - Unsafe ActiveX control

Hi,

I would prefer not to reply to this post directly, but if possible can
you please mention the following (anonymously):

----------
"Safe for Scripting" simply means that the control is safe to be used
from untrusted callers. SFS controls can access files and other
resources if it is in a controlled way (eg, with the consent of the
user). Windows Update is safe because it only allows itself to be hosted
from the Windows Update site. If you try and host the control from
another domain, the control will not work. Since the Windows Update site
only ever uses the control for "good" purposes, and requires the user's
consent to install patches, etc. it is considered "Safe for Scripting".
_All_ ActiveX controls can access memory and registers directly, whether
they are marked as safe or not, since they typically are implemented in
native code ;-)

Windows Update does not require you to run "unsafe" controls;
unfortunately the generic error that appears when you disable scripting
of _safe_ controls makes it sound like there are _unsafe_ controls. If
you enable scripting of "safe" controls then the site should work fine.
If you are concerned about securing the browser, I recommend that you
place Windows Update in the "Trusted Sites" zone and run that in the
"Medium" security mode, and run the rest of the "Internet Zone" in
"High" mode, although this will break a lot of sites.

-----Original Message-----
From: Jackson, Chris [mailto:CJackson@bridgecom.com]
Sent: Thursday, 17 July 2003 10:35 AM
To: 'Siddhartha Jain(IT)'; BUGTRAQ@SECURITYFOCUS. COM
Subject: RE: Windows Update - Unsafe ActiveX control

> "An ActiveX control on this page is not safe. Your current security
settings
> prohibit running unsafe controls on this page. As a result, this page
> may not display as intended."
> So Microsoft expects me download critical patches using an unsafe
> ActiveX control??

Safe for Scripting indicates that a control does not access files,
memory, or registers directly. The only purpose of the Windows Update
control is to access (and update) files directly, so it should not be
marked as safe for scripting.

--
Chris Jackson
Software Engineer
Microsoft MVP
--

[Cesar]

Hi.

I wouldn't consider Windows Update ActiveX as safe,
the ActiveX has dangerous methods, for example it can
reboot the computer. Of course the ActiveX checks for
the current site and if it's not Windows Update site
it won't work, but if there is some XSS hole in
Windows Update site or if there is a bug in IE that
allows to trick the URL, then the ActiveX becomes very
dangerous. In my opinion restricting an ActiveX to a
specific site only reduce the attack surface but it
doesn't make an ActiveX safe.

Cesar.
--- Dave Ahmad <da@securityfocus.com> wrote:
>
> ---------- Forwarded message ----------
> Date: Thu, 17 Jul 2003 XX:XX:XX
> To: Dave Ahmad <da@securityfocus.com>
> Subject: FW: Windows Update - Unsafe ActiveX control
>
> Hi,
>
> I would prefer not to reply to this post directly,
> but if possible can
> you please mention the following (anonymously):
>
> ----------
> "Safe for Scripting" simply means that the control
> is safe to be used
> from untrusted callers. SFS controls can access
> files and other
> resources if it is in a controlled way (eg, with the
> consent of the
> user). Windows Update is safe because it only allows
> itself to be hosted
> from the Windows Update site. If you try and host
> the control from
> another domain, the control will not work. Since the
> Windows Update site
> only ever uses the control for "good" purposes, and
> requires the user's
> consent to install patches, etc. it is considered
> "Safe for Scripting".
> _All_ ActiveX controls can access memory and
> registers directly, whether
> they are marked as safe or not, since they typically
> are implemented in
> native code ;-)
>
> Windows Update does not require you to run "unsafe"
> controls;
> unfortunately the generic error that appears when
> you disable scripting
> of _safe_ controls makes it sound like there are
> _unsafe_ controls. If
> you enable scripting of "safe" controls then the
> site should work fine.
> If you are concerned about securing the browser, I
> recommend that you
> place Windows Update in the "Trusted Sites" zone and
> run that in the
> "Medium" security mode, and run the rest of the
> "Internet Zone" in
> "High" mode, although this will break a lot of
> sites.
>


__________________________________
Do you Yahoo!?
SBC Yahoo! DSL - Now only $29.95 per month!
http://sbc.yahoo.com

>if there is some XSS hole in
> Windows Update site or if there is a bug in IE that
> allows to trick the URL,

then the attacker can use Windows Update ActiveX to:
reboot your machine;
get detailed information on computer - computer name, hardware, isAdmin, etc.

BUT it's hard for the attacker to execute his EXE. i've traced into the module("IUENGINE.TEXT").

they first create the directory(API:"CreateDirectoryW")
then they download the EXE file to the newly created directory. soon after that, they verify its digest (API:"LSTRCMPIW"). at last they verify it with "WinTrust.TEXT" - which i am unable to bypass. if any of the check fails, they delete the file(API:"Dele
teFileW").

assuming we already got WINDOWSUPDATE.MICROSOFT.COM( then we easily got MYCOMPUTER):

the only chance is:
"DeleteFileW" fails.

but chances are very very slim.

so generally speaking(generally speaking, we can't break WinTrust), the maximum risk is "RebootMachine" - nothing more.

just as a reminder



best wishes

die

-----------------------
umbrella.mx.tc - http://umbrella.mx.tc
safecenter - http://www.safecenter.net
make notes easily - http://domex.int.tc




----- Original Message -----
From:Cesar <cesarc56@yahoo.com>
To:bugtraq@securityfocus.com
Subject:Re: FW: Windows Update - Unsafe ActiveX control (fwd)
Date:Sat, 19 Jul 2003 01:15:06 +0800
> Hi.
>
> I wouldn't consider Windows Update ActiveX as safe,
> the ActiveX has dangerous methods, for example it can
> reboot the computer. Of course the ActiveX checks for
> the current site and if it's not Windows Update site
> it won't work, but if there is some XSS hole in
> Windows Update site or if there is a bug in IE that
> allows to trick the URL, then the ActiveX becomes very
> dangerous. In my opinion restricting an ActiveX to a
> specific site only reduce the attack surface but it
> doesn't make an ActiveX safe.
>
> Cesar.
> --- Dave Ahmad <da@securityfocus.com> wrote:
> >
> > ---------- Forwarded message ----------
> > Date: Thu, 17 Jul 2003 XX:XX:XX
> > To: Dave Ahmad <da@securityfocus.com>
> > Subject: FW: Windows Update - Unsafe ActiveX control
> >
> > Hi,
> >
> > I would prefer not to reply to this post directly,
> > but if possible can
> > you please mention the following (anonymously):
> >
> > ----------
> > "Safe for Scripting" simply means that the control
> > is safe to be used
> > from untrusted callers. SFS controls can access
> > files and other
> > resources if it is in a controlled way (eg, with the
> > consent of the
> > user). Windows Update is safe because it only allows
> > itself to be hosted
> > from the Windows Update site. If you try and host
> > the control from
> > another domain, the control will not work. Since the
> > Windows Update site
> > only ever uses the control for "good" purposes, and
> > requires the user's
> > consent to install patches, etc. it is considered
> > "Safe for Scripting".
> > _All_ ActiveX controls can access memory and
> > registers directly, whether
> > they are marked as safe or not, since they typically
> > are implemented in
> > native code ;-)
> >
> > Windows Update does not require you to run "unsafe"
> > controls;
> > unfortunately the generic error that appears when
> > you disable scripting
> > of _safe_ controls makes it sound like there are
> > _unsafe_ controls. If
> > you enable scripting of "safe" controls then the
> > site should work fine.
> > If you are concerned about securing the browser, I
> > recommend that you
> > place Windows Update in the "Trusted Sites" zone and
> > run that in the
> > "Medium" security mode, and run the rest of the
> > "Internet Zone" in
> > "High" mode, although this will break a lot of
> > sites.
> >
>
>
> __________________________________
> Do you Yahoo!?
> SBC Yahoo! DSL - Now only $29.95 per month!
> http://sbc.yahoo.com
>
>

______________________________________

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