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TUCoPS :: Windows Apps :: n-081.txt
Microsoft Cumulative Patch for Outlook Express (CIAC N-081)

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The U.S. Department of Energy
Computer Incident Advisory Capability
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INFORMATION BULLETIN

Microsoft Cumulative Patch for Outlook Express
[Microsoft Security Bulletin MS03-014]

April 24, 2003 20:00 GMT Number N-081
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PROBLEM: A vulnerability exists in the MHTML URL Handler that allows any
file that can be rendered as text to be opened and rendered as
part of a page in Internet Explorer. If the text file contained
script, that script would execute when the file was accessed.
SOFTWARE: * Microsoft Outlook Express 5.5
* Microsoft Outlook Express 6.0
DAMAGE: Exploiting the vulnerability would allow an attacker the same
privileges as the user.
SOLUTION: Apply patch as indicated in Microsoft's bulletin.
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VULNERABILITY The risk is MEDIUM. An attacker would have to host a web site
ASSESSMENT: or send a malicious email that contained a web page used to
exploit this vulnerability and entice, or lure, a user to visit
it.
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LINKS:
CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/n-081.shtml
ORIGINAL BULLETIN:
http://www.microsoft.com/technet/treeview/
default.asp?url=/technet/security/bulletin/MS03-014.asp
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[***** Start Microsoft Security Bulletin MS03-014 *****]

Microsoft Security Bulletin MS03-014

Cumulative Patch for Outlook Express (330994)
Originally posted: April 23, 2003

Summary
Who should read this bulletin: Customers using Outlook Express.

Impact of vulnerability: This bulletin addresses a vulnerability
that could allow an attacker to run code of the attacker’s
choice on a user’s machine. To exploit the vulnerability,
attacker would have to be able to cause Windows to open a
specially constructed MHTML URL, either on a web site or included
in an HTML email message.

Maximum Severity Rating: Critical

Recommendation: Customers should install the patch at the
earliest opportunity.

Affected Software:

* Microsoft Outlook Express 5.5
* Microsoft Outlook Express 6.0

Technical details
Technical description:

MHTML stands for MIME Encapsulation of Aggregate HTML. MHTML is
an Internet standard that defines the MIME (Multipurpose Internet
Mail Extensions) structure used to send HTML content in e-mail
message bodies. The MHTML URL Handler in Windows is part of
Outlook Express and provides a URL type that can be used on the
local machine. This URL type (MHTML://) allows MHTML documents to
be launched from a command line, from Start/Run, using Windows
Explorer or from within Internet Explorer.

A vulnerability exists in the MHTML URL Handler that allows any
file that can be rendered as text to be opened and rendered as
part of a page in Internet Explorer. As a result, it would be
possible to construct a URL that referred to a text file that was
stored on the local computer and have that file render as HTML.
If the text file contained script, that script would execute when the
file was accessed. Since the file would reside on the local computer,
it would be rendered in the Local Computer Security Zone. Files that
are opened within the Local Computer Zone are subject to fewer
restrictions than files opened in other security zones.

Using this method, an attacker could attempt to construct a URL and
either host it on a website or send it via email. In the web based
scenario, where a user then clicked on a URL hosted on a website, an
attacker could have the ability to read or launch files already present
on the local machine. In the case of an e-mail borne attack, if the
user was using Outlook Express 6.0 or Outlook 2002 in their default
configurations, or Outlook 98 or 2000 in conjunction with the Outlook
Email Security Update, then an attack could not be automated and the
user would still need to click on a URL sent in the e-mail. However
if the user was not using Outlook Express 6.0 or Outlook 2002 in their
default configurations, or Outlook 98 or 2000 in conjunction with the
Outlook Email Security Update, the attacker could cause an attack to
trigger automatically without the user having to click on a URL
contained in an e-mail. In both the web based and e-mail based cases,
any limitations on the user’s privileges would also restrict the
capabilities of the attacker’s script.

Applying the update listed in Microsoft Security Bulletin MS03-004 --
Cumulative Patch for Internet Explorer—will help block an attacker
from being able to load a file onto a user’s computer and prevent the
passing of parameters to an executable. This means that an attacker
could only launch a program that already existed on the computer—provided
the attacker was aware of the location of the program—and would not be
able to pass parameters to the program for it to execute.

MHTML is a standard for exchanging HTML content in e-mail and as a result
the MHTML URL Handler function has been implemented in Outlook Express.
Internet Explorer can also render MHTML content, however the MHTML
function has not been implemented separately in Internet Explorer –
it simply uses Outlook Express to render the MHTML content.

Mitigating factors:

* For the web-based scenario, the attacker would have to host a web site
that contained a web page used to exploit this vulnerability and entice a
user to visit it. An attacker would have no way to force a user to visit
the site. Instead, the attacker would need to lure the user there,
typically by getting the user to click on a link to the attacker's site.

* The HTML mail-based attack scenario would be blocked by Outlook Express
6.0 and Outlook 2002 in their default configurations, and by Outlook 98
and 2000 if used in conjunction with the Outlook Email Security Update.

* Exploiting the vulnerability would allow the attacker only the same
privileges as the user. Users whose accounts are configured to have few
privileges on the system would be at less risk than ones who operate with
administrative privileges.

* If the cumulative patch for Internet Explorer MS03-004 has been installed,
known means by which an attacker may place a file onto a user’s computer
will be blocked.

* In order to invoke an executable already present on the local system, an
attacker must know the path to that executable.

Severity Rating: Outlook Express 5.5 Critical
Outlook Express 6.0 Critical
The above assessment is based on the types of systems affected by the
vulnerability, their typical deployment patterns, and the effect that
exploiting the vulnerability would have on them.

Vulnerability identifier: CAN-2002-0980

Tested Versions:
Microsoft tested Internet Explorer versions 5.01 SP3, 5.5 SP2, 6.0 Gold
and 6.0 SP1 as well as Outlook Express versions 5.5 SP2, 6.0 Gold and
6.0 SP1 for this vulnerability. Versions of IE prior to 5.01 Service Pack 3
are no longer eligible for hotfix support. More information on Windows
Operating System Components Lifecycles is available from:
http://microsoft.com/windows/lifecycle/desktop/consumer/components.mspx.

Patch availability

Download locations for this patch

* Microsoft Outlook Express
http://www.microsoft.com/windows/ie/downloads/critical/330994/default.asp

Additional information about this patch

Installation platforms:
This patch can be installed on systems running:

* The OE 5.5 SP2 patch can be installed on systems running Internet Explorer
5.5 Service Pack 2 Windows 98 SE, Windows Millenium, Windows NT 4.0 Service
Pack 6a, Windows 2000 Service Pack 2 and Windows 2000 Service Pack 3.

* The OE 6.0 patch can be installed on systems running Windows XP Gold.

* The OE 6.0 SP1 patch can be installed on system running Internet Explorer
6.0 Service Pack 1 on Windows 98 SE, Windows Millenium, Windows NT 4.0
Service Pack 6a, Windows 2000 Service Pack 2, Windows 2000 Service Pack 3,
and Windows XP Service Pack 1

Inclusion in future service packs:
The fix for this issue will be included in Internet Explorer 6.0 Service Pack 2.

Reboot needed: No

Patch can be uninstalled: Yes

Superseded patches: This is a cumulative patch for Outlook Express, and includes
the fix described in Microsoft Security Bulletin MS02-058.

Verifying patch installation:

* To verify that the patch has been installed on the machine, open IE, select
Help, then select About Internet Explorer and confirm that Q330994 is listed
in the Update Versions field.
* To verify the individual files, use the patch manifest provided in Knowledge
Base article 330994.

Caveats:
None

Localization:
Localized versions of this patch are available at the locations discussed in
“Patch Availability”.

Obtaining other security patches:
Patches for other security issues are available from the following locations:

* Security patches are available from the Microsoft Download Center, and can
be most easily found by doing a keyword search for "security_patch".
* Patches for consumer platforms are available from the WindowsUpdate
web site

Other information:
Support:

* Microsoft Knowledge Base article 330994 discusses this issue. Knowledge Base
articles can be found on the Microsoft Online Support web site.

* Technical support is available from Microsoft Product Support Services.
There is no charge for support calls associated with security patches.

Security Resources: The Microsoft TechNet Security Web Site provides additional
information about security in Microsoft products.

Disclaimer:
The information provided in the Microsoft Knowledge Base is provided "as is"
without warranty of any kind. Microsoft disclaims all warranties, either
express or implied, including the warranties of merchantability and fitness
for a particular purpose. In no event shall Microsoft Corporation or its
suppliers be liable for any damages whatsoever including direct, indirect,
incidental, consequential, loss of business profits or special damages, even
if Microsoft Corporation or its suppliers have been advised of the possibility
of such damages. Some states do not allow the exclusion or limitation of
liability for consequential or incidental damages so the foregoing limitation
may not apply.

Revisions:

* V1.0 April 23, 2003: Bulletin Created.

[***** End Microsoft Security Bulletin MS03-014 *****]

_______________________________________________________________________________

CIAC wishes to acknowledge the contributions of Microsoft Corporation for the
information contained in this bulletin.
_______________________________________________________________________________

CIAC, the Computer Incident Advisory Capability, is the computer
security incident response team for the U.S. Department of Energy
(DOE) and the emergency backup response team for the National
Institutes of Health (NIH). CIAC is located at the Lawrence Livermore
National Laboratory in Livermore, California. CIAC is also a founding
member of FIRST, the Forum of Incident Response and Security Teams, a
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among computer security teams worldwide.

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This document was prepared as an account of work sponsored by an
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Government nor the University of California nor any of their
employees, makes any warranty, express or implied, or assumes any
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