N-135: Microsoft Cumulative Patch for Internet Explorer

10/3/03 - Updated Microsoft Security Bulletin MS03-032 to reflect changes in 
the Technical details section, Additional Information about this patch section, 
and Revisions section.


[***** Start Microsoft Security Bulletin MS03-032 *****]

Microsoft Security Bulletin MS03-032

Cumulative Patch for Internet Explorer (822925)
Originally posted: August 20, 2003
Updated: September 8, 2003

Summary

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

Impact of vulnerability: Two new vulnerabilities, the most serious 
of which could enable an attacker to run arbitrary code on a user’s 
system if the user either browsed to a hostile Web site or opened a 
specially crafted HTML-based email message. 

Maximum Severity Rating: Critical 

Recommendation: System administrators should install the patch 
immediately. 

Affected Software: 
* Microsoft Internet Explorer 5.01 
* Microsoft Internet Explorer 5.5 
* Microsoft Internet Explorer 6.0 
* Microsoft Internet Explorer 6.0 for Windows Server 2003 

An End User version of the bulletin is available at:
http://www.microsoft.com/security/security_bulletins/ms03-032.asp. 

Technical details

Technical description: 

Microsoft originally issued this bulletin on August 20th, 2003. Subsequent to 
issuing the security bulletin, Microsoft received reports that the patch provided 
with this bulletin does not properly correct the Object Type Vulnerability 
(CAN-2003-0532). 

Microsoft also identified a problem that specifically affects Windows XP systems 
that are configured as web servers serving ASP.NET web pages and causes clients 
connecting to the web server to receive an error when they attempt to view pages 
on the site. This problem only affects Windows XP computers that have installed 
Internet Information Services (IIS) 5.1 (which is not installed by default) and 
configured with the .NET Framework version 1.0 to serve ASP.NET based Web pages--
it does not affect other versions of Windows. Microsoft has published a knowledge 
base article 827641 that provides steps to work around this issue while maintaining 
the level of protection provided by the security patch. 

Microsoft is investigating these reports and will re-issue this bulletin with an 
updated patch that corrects these problems.

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

* A vulnerability involving the cross-domain security model of Internet 
  Explorer, which keeps windows of different domains from sharing information. 
  This flaw could result in the execution of script in the My Computer zone. 
  To exploit this flaw, an attacker would have to host a malicious Web site 
  that contained a Web page designed to exploit this particular vulnerability 
  and then persuade a user to visit that site. After the user has visited the 
  malicious Web site, it would be possible for the attacker to run malicious 
  script by misusing the method Internet Explorer uses to retrieve files from 
  the browser cache, and cause that script to access information in a 
  different domain. In the worst case, this could enable the Web site 
  operator to load malicious script code onto a user's system in the security 
  context of the My Computer zone. In addition, this flaw could also enable 
  an attacker to run an executable file that was already present on the local 
  system or view files on the computer. The flaw exists because a file from 
  the Internet or intranet with a maliciously constructed URL can appear in
  the browser cache running in the My Computer zone. 

* A vulnerability that occurs because Internet Explorer does not properly 
  determine an object type returned from a Web server. It could be possible 
  for an attacker who exploited this vulnerability to run arbitrary code on 
  a user's system. If a user visited an attacker's Web site, it would be 
  possible for the attacker to exploit this vulnerability without any other 
  user action. An attacker could also craft an HTML–based e-mail that would 
  attempt to exploit this vulnerability.

This patch also sets the Kill Bit on the BR549.DLL ActiveX control. This 
control implemented support for the Windows Reporting Tool, which is no 
longer supported by Internet Explorer. The control has been found to contain 
a security vulnerability. To protect customers who have this control 
installed, the patch prevents the control from running or from being 
reintroduced onto users' systems by setting the Kill Bit for this control. 
This issue is discussed further in Microsoft Knowledge Base article 822925. 

In addition to these vulnerabilities, a change has been made to the way 
Internet Explorer renders HTML files. This change addresses a flaw in the 
way Internet Explorer renders Web pages that could cause the browser or 
Outlook Express to fail. Internet Explorer does not properly render an input 
type tag. A user visiting an attacker's Web site could allow the attacker to 
exploit the vulnerability by viewing the site. In addition, an attacker could 
craft a specially formed HTML–based e-mail that could cause Outlook Express 
to fail when the e-mail was opened or previewed.

This patch also contains a modification to the fix for the Object Type 
vulnerability (CAN-2003-0344) corrected in Microsoft Security Bulletin 
MS03-020. The modification corrects the behavior of the fix to prevent the 
attack on specific languages.

To exploit these flaws, the attacker would have to create a specially formed 
HTML–based e-mail and send it to the user. Alternatively an attacker would 
have to host a malicious Web site that contained a Web page designed to 
exploit these vulnerabilities. The attacker would then have to persuade a 
user to visit that site. 

As with the previous Internet Explorer cumulative patches released with 
bulletins MS03-004, MS03-015, and MS03-020 this cumulative patch will cause 
window.showHelp( ) to cease to function if you have not applied the HTML Help 
update. If you have installed the updated HTML Help control from Knowledge 
Base article 811630, you will still be able to use HTML Help functionality 
after applying this patch. 

Mitigating factors: 

* By default, Internet Explorer on Windows Server 2003 runs in Enhanced 
  Security Configuration. This default configuration of Internet Explorer 
  blocks these attacks. If Internet Explorer Enhanced Security Configuration  
  has been disabled, the protections put in place that prevent these 
  vulnerabilities from being exploited would be removed. 

* In the Web–based attack scenario, the attacker would have to host a Web 
  site that contained a Web page used to exploit these vulnerabilities. An 
  attacker would have no way to force users to visit a malicious Web site 
  outside the HTML–based e-mail vector. Instead, the attacker would need to 
  lure them there, typically by getting them to click a link that would take 
  them to the attacker's site. 

* Code that executed on the system would only run under the privileges of the 
  logged-on user. 

Severity Rating:

 		Internet     Internet    Internet    Internet    Internet 	
		Explorer     Explorer    Explorer    Explorer    Explorer
		5.01 SP3     5.5 SP2     6.0 Gold    6.0 SP1     6.0 for 
                                                                 Windows 
								 Server 2003 
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
BR549.DLL  
Buffer Overrun 	Critical     Critical    Critical    Critical    Moderate 
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Browser Cache 
Script Execution 
in My Computer 
Zone 		Important    Important   Important   Important   Moderate 
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Object Tag 
Vulnerability 	Critical     Critical 	 Critical    Critical    Moderate 
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Aggregate 
Severity of all 
issues included 
in this patch 	Critical     Critical    Critical    Critical    Moderate 
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

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: 

* BR549.DLL Buffer Overrun:CAN-2003-0530 
* Browser Cache Script Execution in My Computer Zone:CAN-2003-0531 
* Object Type Vulnerability:CAN-2002-0532 

Tested Versions:
Internet Explorer versions 5.01 Service Pack 3, Internet Explorer 5.01 
Service Pack 4, Internet Explorer 5.5 Service pack 2, Internet Explorer 6.0 
and Internet Explorer 6.0 Service Pack 1 were tested for these 
vulnerabilities. Previous versions are no longer supported, and may or may 
not be affected by these vulnerabilities. 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

* All version except Microsoft Internet Explorer 6.0 for Windows Server 2003
* Microsoft Internet Explorer 6.0 for Windows Server 2003

Additional information about this patch

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

* Internet Explorer 5.01 running on Windows 2000 systems with Service Pack 3 
  or Service Pack 4 installed. 

* The Internet Explorer 5.5 patch can be installed on systems running 
  Internet Explorer 5.5 Service Pack 2. 

* The Internet Explorer 6.0 patch can be installed on systems running 
  IE 6.0 Gold or Internet Explorer 6.0 Service Pack 1. 
  
Inclusion in future service packs:
The fix for these issues will be included in Windows XP Service Pack 2 and 
Windows Server 2003 Service Pack 1 

Reboot needed: Yes - After reboot, an administrator logon is required for: 

Internet Explorer 5.01 on Microsoft Windows 2000 and Microsoft Windows NT 4.0 
Internet Explorer 5.5 on Microsoft Windows 2000 

Patch can be uninstalled: Yes 

Superseded patches: This patch supersedes the one provided in Microsoft 
Security Bulletin MS03-020, 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 Q822925 is 
  listed in the Update Versions field. 

  Note that you can not use this method on Windows Server 2003 or Windows XP 
  64-Bit Edition Version 2003, as the Update Versions field is not updated 
  by the package for these operating systems.

* To verify the individual files, use the patch manifest provided in 
  Knowledge Base article 822925. 

Caveats:
If you have not installed the updated HTML Help control from Knowledge Base 
article 811630, you will not be able to use some HTML Help functionality 
after applying this update. In order to restore that functionality, users 
need to download the updated HTML Help control (811630). Users should also 
note that when the latest version of HTML Help is installed, the following 
limitations will occur when a help file is opened with the showHelp method: 

* Only supported protocols can be used with showHelp to open a web page or 
  help (.chm) file. 

* The shortcut function supported by HTML Help will be disabled when the help 
  file is opened with showHelp This will not affect the shortcut functionality 
  if the same CHM file is opened by the user manually by double-clicking on 
  the help file, or by through an application on the local system using the 
  HTMLHELP( ) API. 

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: 

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

* Yu-Arai of LAC for reporting the language specific variant of the MS03-020 
  Object Type vulnerability (CAN-2003-0344), as well as the Browser Cache 
  Script Execution in My Computer Zone problem to us.

* eEye Digital Security for reporting the Object Type vulnerability to us.

* Greg Jones from KPMG UK for reporting the BR549.DLL Buffer Overrun problem 
  to us.

Support: 

* Microsoft Knowledge Base article 822925, 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 (August 20, 2003): Bulletin Created. 
V1.1 (August 25, 2003): Added information regarding ASP.NET related issues 
with Windows XP patch. 
V1.2 (August 28, 2003): Added details to reboot information in Additional 
Information section. 
V1.3 (September 8, 2003): Added information regarding reports that the patch 
provided does not properly correct the Object Type Vulnerability (CAN-2003-0532) 


[***** End Microsoft Security Bulletin MS03-032 *****]

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