__________________________________________________________

                       The U.S. Department of Energy
                     Computer Incident Advisory Capability
                           ___  __ __    _     ___
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             __________________________________________________________

                             INFORMATION BULLETIN

                Microsoft Cumulative Patch for Internet Explorer
                     [Microsoft Security Bulletin MS02-023]

May 23, 2002 21:00 GMT                                            Number M-082
______________________________________________________________________________
PROBLEM:       There are six new vulnerabilities in Internet Explorer.

               * Cross-Site Scripting in Local HTML Resource 
               * Local Information Disclosure through HTML object 
               * Script within Cookies Reading Cookies 
               * Zone Spoofing through Malformed Web Page 
               * Two "Content Disposition" Variants 

A description of each vulnerability, if exploitable, is provided within 
Microsoft's Security bulletin.

PLATFORM:      Internet Explorer 5.01, Internet Explorer 5.5, and Internet 
               Explorer 6.0. 
DAMAGE:        The aggregate of severity is based on the types of systems 
               affected by the vulnerability, their deployment patterns, and 
               the effect that exploiting the vulnerability would have on 
               them. 
SOLUTION:      Apply appropriate patch for appropriate Internet Explorer 
               version as prescribed by Microsoft. 
______________________________________________________________________________
VULNERABILITY  The risk is HIGH. The most serious vulnerability may allow an 
ASSESSMENT:    attacker to run code of choice. 
______________________________________________________________________________
LINKS: 
 CIAC BULLETIN:      http://www.ciac.org/ciac/bulletins/m-082.shtml 
 ORIGINAL BULLETIN:                                                           
                     http://www.microsoft.com/technet/treeview/
                             default.asp?url=/technet/security/
                               bulletin/MS02-023.asp
______________________________________________________________________________

[***** Start Microsoft Security Bulletin MS02-023 *****]
 
Microsoft Security Bulletin MS02-023


15 May 2002 Cumulative Patch for Internet Explorer (Q321232)
Originally posted: May 15, 2002

Summary
Who should read this bulletin: Customers using Microsoft® 
Internet Explorer 

Impact of vulnerability: Six new vulnerabilities, the most serious
of which could allow code of attacker's choice to run.

Maximum Severity Rating: Critical 

Recommendation: Consumers using the affected versions of IE should 
install the patch immediately. 

Affected Software: 

Microsoft Internet Explorer 5.01 
Microsoft Internet Explorer 5.5 
Microsoft Internet Explorer 6.0 

Technical details

Technical description: 

This is a cumulative patch that includes the functionality of all 
previously released patches for IE 5.01, 5.5 and 6.0. In addition, 
it eliminates the following six newly discovered vulnerabilities:


* A cross-site scripting vulnerability in a Local HTML Resource. IE ships 
with several files that contain HTML on the local file system to provide 
functionality. One of these files contains a cross-site scripting 
vulnerability that could allow a script to execute as if it were run by 
the user herself, causing it to run in the local computer zone. An attacker 
could craft a web page that exploits this vulnerability and then either 
host that page on a web server or send it as HTML email. When the web page 
was viewed and the attacker's script run, the attacker's script would be 
injected into the local resource, where it would run in the Local Computer 
zone, allowing it to run with fewer restrictions than it would in the 
Internet Zone.
* An information disclosure vulnerability related to the use of am HTML 
object provides that support for Cascading Style Sheets that could allow an
attacker to read, but not add, delete or change, data on the local system. 
An attacker could craft a web page that exploits this vulnerability and then 
either host that page on a web server or send it as HTML email. When the page 
was viewed, the element would be invoked. Successfully exploiting this 
vulnerability, however, requires exact knowledge of the location of the 
intended file to be read on the user's system. Further, it requires that the 
intended file contain a single, parcicular ASCII character.
* An information disclosure vulnerability related to the handling of script 
within cookies that could allow one site to read the cookies of another. 
An attacker could build a special cookie containing script and then construct 
a web page that would deliver that cookie to the user's system and invoke it. 
He could then send that web page as mail or post it on a server. When the page 
executed and invoked the script in the cookie, it could potentially read or 
alter the cookies of another site. Successfully exploiting this, however, 
would require that the attacker know the exact name of the cookie as stored 
on the file system to be read successfully.
* A zone spoofing vulnerability that could allow a web page to be incorrectly 
reckoned to be in the Intranet zone or, in some very rare cases, in the 
Trusted Sites zone. An attacker could construct a web page that exploits this 
vulnerability and attempt to entice the user to visit the web page. If the 
attack were successful, the page would be run with fewer security restrictions 
than is appropriate.
* Two variants of the "Content Disposition" vulnerability discussed in 
Microsoft Security Bulletin MS01-058 affecting how IE handles downloads when a 
downloadable file's Content-Disposition and Content-Type headers are 
intentionally malformed. In such a case, it is possible for IE to believe that 
a file is a type safe for automatic handling, when in fact it is executable 
content. An attacker could seek to exploit this vulnerability by constructing 
a specially malformed web page and posting a malformed executable file. He 
could then post the web page or mail it to the intended target. These two new 
variants differ from the original vulnerability in that they for a system to 
be vulnerable, it must have present an application present that, when it is 
erroneously passed the malformed content, chooses to hand it back to the 
operating system rather than immediately raise an error. A successful attack, 
therefore, would require that the attacker know that the intended victim has 
one of these applications present on their system.

Finally, it introduces a behavior change to the Restricted Sites zone. 
Specifically, it disables frames in the Restricted Sites zone. Since the 
Outlook Express 6.0, Outlook 98 and Outlook 2000 with the Outlook Email 
Security Update and Outlook 2002 all read email in the Restricted Sites zone 
by default, this enhancement means that those products now effectively 
disable frames in HTML email by default. This new behavior makes it impossible 
for an HTML email to automatically open a new window or to launch the download 
of an executable.

Mitigating factors: 

Cross-Site Scripting in Local HTML Resource:


* Outlook 98 and 2000 (after installing the Outlook Email Security Update), 
Outlook 2002, and Outlook Express 6 all open HTML mail in the Restricted 
Sites Zone. As a result, customers using these products would not be at risk
from automated email-borne attacks. However, these customers can still be 
attacked if they choose to click on a hyperlink in a malicious HTML email.
* Customers using Outlook 2002 SP1 who have enabled the "Read as Plain Text" 
feature would be immune from the HTML email attack. This is because this 
feature disables all HTML elements, including scripting, from mail when it 
is displayed.
* Any limitations on the rights of the user's account would also limit the 
actions of the attacker's script.
* Customers who exercise caution in what web sites they visit or who place 
unknown or untrusted sites in the Restricted Sites zone can potentially 
protect themselves from attempts to exploit this issue on the web.

Local Information Disclosure through HTML Object: 


* It can only be used to read information. It cannot add, change or delete 
any information.
* The attacker would need to know the exact name and location on the system 
of any file they attempted to read.
* Only files that contained a particular, individual ASCII character could 
be read. If this single character is not present, the attempt to read the 
file would fail.
* Outlook 98 and 2000 (after installing the Outlook Email Security Update), 
Outlook 2002, and Outlook Express 6 all open HTML mail in the Restricted 
Sites Zone. As a result, customers using these products would not be at risk 
from automated email-borne attacks. However, these customers can still be 
attacked if they choose to click on a hyperlink in a malicious HTML email.
* Customers using Outlook 2002 SP1 who have enabled the "Read as Plain Text" 
feature would be immune from the HTML email attack. This is because this 
feature disables all HTML elements, including scripting, from mail when it 
is displayed.

Script within Cookies Reading Cookies: 


* The specific information an attacker could access would depend on what 
information a site has chosen to store in its cookies. Best practices 
strongly recommend against storing sensitive information in cookies.
* Mounting a successful attack requires that the attacker know the exact 
name and location of the target cookie. This vulnerability provides no 
means for an attacker to acquire that information.
* Outlook 98 and 2000 (after installing the Outlook Email Security Update),
Outlook 2002, and Outlook Express 6 all open HTML mail in the Restricted 
Sites Zone. As a result, customers using these products would not be at 
risk from automated email-borne attacks. However, these customers can 
still be attacked if they choose to click on a hyperlink in a malicious 
HTML email.
* Customers using Outlook 2002 SP1 who have enabled the "Read as Plain Text" 
feature would be immune from the HTML email attack. This is because this 
feature disables all HTML elements, including scripting, from mail when it 
is displayed.

Zone Spoofing through Malformed Web Page: 


* A successful attack would require NetBIOS connectivity between the user and 
the attacker's site. Any filtering of NetBIOS, such as that found by ISP's or 
at the firewall perimeter, would thwart attempts to exploit this 
vulnerability.
* Any attempt to render a web site in the Trusted Sites zone would require 
very specific knowledge of custom configuration made by the user. This aspect 
of the vulnerability is not exploitable by default, nor does the 
vulnerability give the means to acquire the necessary information for that 
attack.

New Variants of the "Content Disposition" Vulnerability:


* Any successful attempt to exploit this vulnerability requires that the 
attacker know that the intended target have specific versions of specific 
applications on their system. The vulnerability gives no means for an attacker
to know what applications or versions are present on the system. 
* Any attempt to exploit the vulnerability requires that the attacker host a 
malicious executable on a server accessible to the intended victim. If the 
hosting server is unreachable for any reason, such as DNS blocking or the 
server being taken down, the attack would fail.

Severity Rating:
Cross-Site Scripting in Local HTML Resource:

			Internet Servers 	Intranet Servers 	Client Systems
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Internet Explorer 5.01 	None 			None 			None 
Internet Explorer 5.5 	None 			None 			None 
Internet Explorer 6.0 	Moderate 		Moderate 		Critical
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Local Information Disclosure through HTML Object:

			Internet Servers 	Intranet Servers 	Client Systems
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Internet Explorer 5.01 	Moderate 		Moderate 		Critical 
Internet Explorer 5.5 	Moderate 		Moderate 		Critical 
Internet Explorer 6.0 	Moderate 		Moderate 		Critical
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Script within Cookies Reading Cookies:

			Internet Servers 	Intranet Servers 	Client Systems
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Internet Explorer 5.01 	None 			None 			None 
Internet Explorer 5.5 	Moderate 		Moderate 		Critical 
Internet Explorer 6.0 	Moderate 		Moderate 		Critical
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Zone Spoofing through Malformed Web Page:

			Internet Servers 	Intranet Servers 	Client Systems
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Internet Explorer 5.01 	Low 			Low 			Low 
Internet Explorer 5.5 	Low 			Low 			Low 
Internet Explorer 6.0 	Low 			Low 			Low
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

New Variants of the "Content Disposition" Vulnerability:

			Internet Servers 	Intranet Servers 	Client Systems
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Internet Explorer 5.01 	Moderate 		Moderate 		Moderate 
Internet Explorer 5.5 	None 			None 			None 
Internet Explorer 6.0 	Moderate 		Moderate 		Moderate
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Aggregate severity of all vulnerabilities eliminated by patch:

			Internet Servers 	Intranet Servers 	Client Systems
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Internet Explorer 5.01 	Critical 		Critical 		Critical 
Internet Explorer 5.5 	Critical 		Critical 		Critical 
Internet Explorer 6.0 	Critical 		Critical 		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. The personal information disclosure vulnerabilities are most 
likely to affect client systems, based on usage patters. The variants of the 
"Content Disposition" vulnerability require knowledge of the software installed on a 
system by the user. The Zone Spoofing vulnerability requires NetBIOS access, which is 
commonly blocked at the perimeter firewall and by ISP's. The aggregate severity 
includes the severity of vulnerabilities announced in previously released security 
bulletins.

Vulnerability identifiers:


* Cross-Site Scripting in Local HTML Resource: CAN-2002-0189
* Local Information Disclosure through HTML object: CAN-2002-0191 
* Script within Cookies Reading Cookies: CAN-2002-0192 
* Zone Spoofing through Malformed Web Page: CAN-2002-0190 
* "Content Disposition" Variants: CAN-2002-0193, CAN-2002-0188

Tested Versions:
The following table indicates which of the currently supported versions of Internet 
Explorer are affected by the vulnerabilities. Versions of IE prior to 5.01 Service 
Pack 2 are no longer eligible for hotfix support. IE 5.01 SP2 is supported only via 
Windows® 2000 Service Packs and Security Roll-up Packages and on Windows NT® 4.0.

			IE 5.01 SP2 	IE 5.5 SP1 	IE 5.5 SP2 	IE 6.0
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Cross-Site Scripting in 
Local HTML Resource 
(CVE-CAN-2002-0189) 	No 		No 		No 		Yes

Local Information 
Disclosure through 
HTML object 
(CAN-2002-0191) 	Yes 		Yes 		Yes 		Yes

Script within Cookies 
Reading Cookies:
(CVE-CAN-2002-0192) 	No 		Yes 		Yes 		Yes

Zone Spoofing through 
Malformed Web Page
(CVE-CAN-2002-0190) 	Yes 		Yes 		Yes 		Yes

New Variants of the 
"Content Disposition" 
Vulnerability 
(CAN-2002-0193 and 
CAN-2002-0188) 		Yes 		No 		No 		Yes
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Patch availability

Download locations for this patch

* http://www.microsoft.com/windows/ie/downloads/critical/Q321232/default.asp

Additional information about this patch

Installation platforms: 

* The IE 5.01 patch can be applied to Windows 2000 Systems with Service Pack 2 or 
Windows NT 4.0 systems with Service Pack 6a.
* The IE 5.5 patch can be installed on systems running IE 5.5 Service Pack 1 or 
Service Pack 2.
* The IE 6.0 patch can be installed on system running IE 6.0 Gold.

Inclusion in future service packs:

* The fixes for these issues will be included in IE 6.0 Service Pack 1. 
* The fixes for the issues affecting IE 5.01 Service Pack 2 will be included in 
Windows 2000 Service Pack 3.

Reboot needed:
Yes

Superseded patches:

* This patch supersedes the one provided in Microsoft Security Bulletin MS02-015, 
which is itself a cumulative patch.

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 Q321232 is listed in the 
Update Versions field.
* To verify the individual files, use the patch manifest provided in Knowledge 
Base article Q321232.

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 
* All patches available via WindowsUpdate also are available in a redistributable 
form from the WindowsUpdate Corporate site.

Other information:

Acknowledgments

Microsoft thanks the following people for working with us to protect customers:

* Jani Laatikainen (jani@laatikainen.net) for reporting one of the 
"Content-Disposition variants.
* Yuu Arai of LAC SNS Team (http://www.lac.co.jp/security/) for reporting one of the 
"Content-Disposition variants.
* Cistobal Bielza Lino and Juan Carlos G. Cuartango from Instituto Seguridad Internet 
(www.instisec.com) for reporting the Zone Spoofing through Malformed Web Page 
vulnerability.

Support: 

* Microsoft Knowledge Base article Q321232 discusses this issue and will be available 
approximately 24 hours after the release of this bulletin. 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 (May 15, 2002): Bulletin Created.
* V1.1 (May 16, 2002): Bulletin updated to correct erroneous information regarding 
attack vectors for the Cross-Site Scripting in Local HTML Resource and Script within 
Cookies Reading Cookies vulnerabilities and the capabilities of locally run scripts.

[***** End Microsoft Security Bulletin MS02-023 *****]

_______________________________________________________________________________

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


CIAC, the Computer Incident Advisory Center, 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
global organization established to foster cooperation and coordination
among computer security teams worldwide.

CIAC services are available to DOE, DOE contractors, and the NIH. CIAC
can be contacted at:
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    E-mail:   ciac@ciac.org

Previous CIAC notices, anti-virus software, and other information are
available from the CIAC Computer Security Archive.

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This document was prepared as an account of work sponsored by an
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employees, makes any warranty, express or implied, or assumes any
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