[8594] in bugtraq
Update to Microsoft Security Bulletin (MS98-015)
daemon@ATHENA.MIT.EDU (Aleph One)
Wed Nov 18 14:05:17 1998
Date: Wed, 18 Nov 1998 12:09:01 -0600
Reply-To: Aleph One <aleph1@DFW.NET>
From: Aleph One <aleph1@DFW.NET>
To: BUGTRAQ@NETSPACE.ORG
---------- Forwarded message ----------
Date: Wed, 18 Nov 1998 10:06:51 -0800
From: Microsoft Product Security <secnotif@MICROSOFT.COM>
To: MICROSOFT_SECURITY@ANNOUNCE.MICROSOFT.COM
Subject: Update to Microsoft Security Bulletin (MS98-015)
The following is a Security Bulletin from the Microsoft Product Security
Notification Service.
Please do not reply to this message, as it was sent from an unattended
mailbox.
********************************
The following is an update to a previously released Microsoft Security
Bulletin. All customers, including those who read the original version of
this bulletin and installed the patch, should read the following and take
the appropriate action.
------------------------------------------------
Update to Microsoft Security Bulletin (MS98-015)
------------------------------------------------
Update available for "Untrusted Scripted Paste" Issue in
Microsoft (r) Internet Explorer (r) 4.01
Originally Posted: October 16, 1998
Last Revised: November 18, 1998
Summary
=======
On November 18th Microsoft released an updated version of the patch for the
"Untrusted Scripted Paste" vulnerability. This vulnerability, also known as
the "Cuartango" vulnerability, could enable a malicious web site operator
to use scripted paste operations to read a file that resides in a known
location on a user's system. The updated patch fixes the original
vulnerability as well as a newly-discovered variant.
Microsoft highly recommends that all affected customers -- including anyone
who downloaded the original patch before November 18 -- download and
install the updated patch to protect their computers.
Issue
=====
The "Untrusted Scripted Paste" issue involves a vulnerability in Internet
Explorer that could allow a malicious web site operator to circumvent
certain Internet Explorer security safeguards. This vulnerability makes it
possible for the operator to read the contents of a file on the user's
computer if he knows the exact name and path of the targeted file. This
could also be used to view the contents of a file on the user's network, if
the user has access to it and the malicious operation knows its direct path
name.
The underlying problem is the ability of a script to use the
Document.ExecCommand function to paste a filename into the file upload
intrinsic control. This should only be possible by explicit user action.
Once the filename has been pasted into the control, a subsequent form
submission could send the file to a remote web site. If the user has
disabled the default warning that is displayed when submitting unencrypted
forms, the file would be sent without any warning to the user. (See
"Administrative Workaround" below for information on re-enabling this
functionality).
Although the original patch corrected the problem, another method of
putting a filename into the file upload intrinsic control was discovered
subsequently. The updated patch addresses both the original problem and the
newly-discovered variant.
Affected Software Versions
==========================
- Microsoft Internet Explorer 4.01 and 4.01 SP1
on Windows NT (r) 4.0, Windows (r) 95
- Microsoft Windows 98, with integrated Internet Explorer
- Microsoft Internet Explorer 4.01 for Windows 3.1 and Windows NT 3.51
This vulnerability could also affect software that uses HTML functionality
provided by Internet Explorer, even if Internet Explorer is not used as
your default browser. All customers that have affected versions of Internet
Explorer on their systems should install this patch, whether or not they
use Internet Explorer for web browsing.
This vulnerability does not affect Internet Explorer 3.x or 4.0 on any
platform. This does not affect any Macintosh or UNIX versions of Internet
Explorer.
What Microsoft is Doing
=======================
On November 18th, Microsoft released an updated version of this patch. The
updated version fixes the original problem, as well as a subsequently
identified variant. This patch is available for downloading from the sites
listed below.
Microsoft has sent this security bulletin to customers subscribing
to the Microsoft Product Security Notification Service (see
http://www.microsoft.com/security/services/bulletin.asp for more
information about this free customer service).
Microsoft has published the following Knowledge Base (KB) articles on this
issue:
- Microsoft Knowledge Base (KB) article Q169245,
Update available for "Untrusted Scripted Paste" Issue
http://support.microsoft.com/support/kb/articles/q169/2/45.asp
(Note: It might take 24 hours from the original posting of this bulletin
for the updated KB article to be visible in the Web-based Knowledge Base.)
What customers should do
========================
Microsoft highly recommends that all affected customers -- including anyone
who downloaded the original patch before November 18 -- download the
updated patch to protect their computers. The complete URL for each
affected software version is given below.
At this writing, only the 32-bit version of the patch is available. The
16-bit version will be available shortly.
Windows 98
----------
Windows 98 customers can obtain the updated patch using Windows Update. To
obtain this patch using Windows Update, launch Windows Update from the
Windows Start Menu and click "Product Updates." When prompted, select 'Yes'
to allow Windows Update to determine whether this patch and other updates
are needed by your computer. If your computer does need this patch, you
will find it listed under the "Critical Updates" section of the page.
Internet Explorer 4.01
----------------------
Customers using Internet Explorer 4.01 can obtain the
patch from the Internet Explorer Security web site,
http://www.microsoft.com/ie/security/paste.htm
Administrative Workaround
=========================
Microsoft strongly encourages customers to apply the patch. However, there
are additional actions that can be taken to ensure safe computing:
If the user has disabled the default warning that is displayed when
submitting unencrypted forms, re-enabling this feature can provide
additional protection. The warning prompt makes sure users are alerted if a
script attempts to submit data using forms. Users should be cautious if
they see this warning when browsing and have not actually chosen to submit
any data.
To turn on this prompt:
1. From Internet Explorer, choose "Internet Options" from
the "View" menu.
2. Click on the tab labeled "Security".
3. Click on "Internet Zone", then click "Customize Settings".
4. Scroll to "Submit non-encrypted form data" and click on
"Prompt".
The same procedure should be followed for the "Restricted Sites" Zone.
Additionally, users who cannot apply the patch immediately can disable
Active Scripting technologies in Internet Explorer to protect themselves
from this issue. Please note that the Zones security feature in Internet
Explorer 4 can be used to disable Active Scripting (VBScript and JScript)
in untrusted or unknown Internet sites, while still permitting it in
trusted and known sites.
To turn off Active Scripting for the "Internet" Zone:
1. From Internet Explorer, choose "Internet Options" from
the "View" menu.
2. Click on the tab labeled "Security".
3. Click on "Internet Zone", then click "Customize Settings".
4. Scroll to the bottom of the list and click on "Disable"
under the "Active Scripting" setting.
The same procedure should be followed for the "Restricted Sites" Zone.
Sites that are trusted to use JScript and VBScript can be added to the
Trusted Zones list. For more information on using Zones, please see the
Online Help included with Internet Explorer.
More Information
================
Please see the following references for more information related to this
issue.
- Microsoft Security Bulletin MS98-015,
Update available for "Untrusted Scripted Paste" Issue
in Microsoft Internet Explorer 4.01, (the Web posted
version of this bulletin),
http://www.microsoft.com/security/bulletins/ms98-015.asp
- Microsoft Knowledge Base (KB) article Q169245,
Update available for "Untrusted Scripted Paste" Issue
http://support.microsoft.com/support/kb/articles/q169/2/45.asp
(Note: It might take 24 hours from the original posting of this bulletin
for the updated KB article to be visible in the Web-based Knowledge Base.)
Obtaining Support on this Issue
===============================
This is a supported patch for Internet Explorer. If you have
problems installing this patch or require technical assistance
with this patch, please contact Microsoft Technical Support.
For information on contacting Microsoft Technical Support, please see
http://support.microsoft.com/support/contact/default.asp
Acknowledgements
================
This bug was originally reported to Microsoft by Juan Carlos Garcia
Cuartango of Spain. Mr. Cuartango also reported the new variant of this
issue. We are grateful for his assistance.
Revisions
=========
- October 16, 1998: Bulletin Created
- November 18, 1998: Updated bulletin to include
information on updated patch that fixes variation
of original issue.
For additional security-related information about Microsoft
products, please visit http://www.microsoft.com/security
------------------------------------------------------------
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