TUCoPS :: Browsers :: n-018.txt

Microsoft Cumulative Patch for Internet Explorer (CIAC N-018)


                       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 MS02-066]

November 21, 2002 18:00 GMT                                       Number N-018
PROBLEM:       There are six new vulnerabilities in Internet Explorer. 
               - Malformed PNG image file failure 
               - Encoded characters information disclosure 
               - Frames cross site scripting 
               - Temporary Internet files folders name reading 
               - Cross domain verification via cached methods 
               - Improper cross domain security validation with frames 
               A description of each vulnerability, if exploitable, is provided 
			   within Microsoft's Security bulletin.
AFFECTED       Internet Explorer 5.01, 5.5, and 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
SOLUTION:      Apply appropriate patch for respective Internet Explorer
               version as prescribed by Microsoft.
VULNERABILITY  The risk is MEDIUM. The most serious vulnerability could enable
ASSESSMENT:    an attacker to execute commands on a user's system.
 CIAC BULLETIN:      http://www.ciac.org/ciac/bulletins/n-018.shtml
 ORIGINAL BULLETIN:  http://www.microsoft.com/technet/treeview/default.asp?url=
 PATCHES:            http://www.microsoft.com/windows/ie/downloads/critical/
[***** Start Microsoft Security Bulletin MS02-066 *****]

Microsoft Security Bulletin MS02-066

Cumulative Patch for Internet Explorer (Q328970)

Originally posted: November 20, 2002


Who should read this bulletin: Customers using Microsoftģ Internet Explorer 

Impact of vulnerability: Six new vulnerabilities, the most serious of which 
could enable an attacker to execute commands on a userís system. 

Maximum Severity Rating: Important 

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

Affected Software: 

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

End User Bulletin: An end user version of this bulletin is available at:

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 buffer overrun vulnerability that occurs because Internet Explorer does 
not correctly check the parameters of a PNG graphics file when it is opened. 
To the best of Microsoftís knowledge, this vulnerability could only be used 
to cause Internet Explorer to fail. The effect of exploiting the vulnerability 
against Internet Explorer would be relatively minor - the user would only need 
to restart the browser to restore normal operation. However, a number of other 
Microsoft products - notably, most Microsoft Office products and Microsoft 
Index Server - rely on Internet Explorer to render PNG files, and exploiting 
the vulnerability against such an application would cause them to fail as well.
Because of this, Microsoft recommends that customers install this patch 
regardless of whether they are using Internet Explorer as their primary
web browser. 

- An information disclosure vulnerability related to the way that Internet 
Explorer handles encoded characters in a URL. This vulnerability could allow 
an attacker to craft a URL containing some encoded characters that would 
redirect a user to a second web site. If a user followed the URL, the 
attacker would be able to piggy-back the userís access to the second website. 
This could allow the attacker to access any information the user shared with 
the second web site. 

- A vulnerability that occurs because under certain circumstances Internet 
Explorer does not correctly check the component that the OBJECT tag calls. 
This could allow an attacker to obtain the name of the Temporary Internet 
Files folder on the userís local machine. The vulnerability would not allow 
an attacker to read or modify any files on the userís local system, since the 
Temporary Internet Files folder resides in the Internet security zone. 
Knowledge of the name of the Temporary Internet Files folder could allow an 
attacker to identify the username of the logged-on user and read other
information in the Temporary Internet Files folder such as cookies.

- Three vulnerabilities that although having differing root causes, have the 
same net effects. All three vulnerabilities result because of incomplete 
security checks being carried out when using particular programming techniques 
in web pages, and would have the effect of allowing one website to access 
information in another domain, including the userís local system. This could 
enable the web site operator to read, but not change, any file on the userís 
local computer that could be viewed in a browser window. In addition, this 
could also enable an attacker to invoke an executable that was already present 
on the local system. 

In addition, the patch sets the Kill Bit on a legacy DirectX ActiveX control 
which has been retired but which has a security vulnerability. This has been 
done to ensure that the vulnerable control cannot be reintroduced onto usersí 
systems and ensures that users who already have the control on their system 
are protected. This is discussed further in Microsoft Knowledge Base 
Article 810202. 

The patch also makes a further refinement to cross domain verification check 
that was first introduced in Internet Explorer Service Pack 1. This is 
discussed further in the Frequently Asked Questions below. 

Mitigating factors: 

With the exception of the Malformed PNG Image File Failure, there are common 
mitigating factors across all of the vulnerabilities: 

- The attacker would have to host a web site that contained a web page used 
to exploit the particular vulnerability. 

- The attacker would have no way to force users to visit the site. Instead, 
the attacker would need to lure them there, typically by getting them to 
click on a link that would take them to the attacker's site. 

- By default, Outlook Express 6.0 and Outlook 2002 open HTML mails in the
Restricted Sites Zone. In addition, Outlook 98 and 2000 open HTML mails in 
the Restricted Sites Zone if the Outlook Email Security Update has been 
installed. Customers who use any of these products would be at no risk from 
an e-mail borne attack that attempted to exploit these vulnerabilities. 

In addition to there are a number of individual mitigating factors: 

Malformed PNG Image File Failure 

- Internet Explorer and other affected applications such as Microsoft Office 
and Microsoft Index Server could be successfully restarted after the failure.
- Microsoft has not identified a method by which this buffer overrun can be 
used to execute code of the attackerís choice on the userís system.
- This vulnerability is not present in Internet Explorer 6 Service Pack 1. 

Encoded Characters Information Disclosure 

- The vulnerability would not enable an attacker to read, modify or execute 
any files on the local system. 

Temporary Internet Files folder Name Reading 

- An attacker could not use this vulnerability to read, delete or modify any 
files on the userís local system other than information contained in the 
Temporary Internet Files folder.
- An attacker could only exploit this vulnerability by having a user visit a 
malicious web site and then follow a malformed link on this malicious web 
site to a second web site that the user trusted.
- This vulnerability is not present in Internet Explorer 6 Service Pack 1. 

Frames Cross Site Scripting, Cross Domain Verification via Cached Methods & 
Improper Cross Domain Security Validation with Frames 

- The vulnerabilities would only allow an attacker to read files on the userís 
local system that can be rendered in a browser window, such as image files, 
HTML files and text files. 

- The vulnerabilities would not provide any way for an attacker to put a 
program of their choice onto another userís system. 

- An attacker would need to know the name and location of any file on the 
system to successfully invoke it. 

- The vulnerabilities could only be used to view or invoke local executables. 
It could not be used to create, delete, or modify arbitrary or malicious files. 

Severity Rating: 
                  Internet       Internet       Internet         Internet
                  Explorer 5.01  Explorer 5.5   Explorer 6.0     Explorer 6.0
                                                Gold             SP1

Malformed PNG     Important      Important      Important        None
Image File 
Encoded           Moderate       Moderate       Moderate         Moderate
Frames Cross      Important      Important      Important        Important
Site Scripting
Temporary         Low            Low            Low              None
Internet Files 
folders Name
Cross Domain      None           Important      Important        Important
Verification via 
Cached Methods
Improper Cross    None           Important      Important        None
Domain Security
Validation with 
Aggregate         Important      Important      Important        Important
Severity of
all issues 
included in
this patch

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 identifiers: 

Malformed PNG Image File Failure: CVE-CAN-2002-1185 
Encoded Characters Information Disclosure: CVE-CAN-2002-1186 
Frames Cross Site Scripting: CVE-CAN-2002-1187 
Temporary Internet Files folder Name Reading: CVE-CAN-2002-1188 
Cross Domain Verification via Cached Methods: CVE-CAN-2002-1254 
Improper Cross Domain Security Validation with Frames: CVE-CAN-2002-1217 

Tested Versions:
Internet Explorer versions 5.01 SP3, 5.5 SP2, 6.0 Gold and 6.0 SP1 were 
tested for these vulnerabilities. Versions of IE prior to 5.01 Service 
Pack 3 are no longer eligible for hotfix support. IE 5.01 SP3 is supported 
only on Windowsģ 2000. More information on Windows Operating System 
Components Lifecycles is available from:

Patch availability

Download locations for this patch 


Additional information about this patch 

Installation platforms: 

- The IE 5.01 patch can be applied to Windows 2000 Systems with Service Pack 3
running IE 5.01 
- The IE 5.5 patch can be installed on systems running Service Pack 2. 
- The IE 6.0 patch can be installed on system running IE 6.0 Gold or IE 6.0 
Service Pack 1. 

Inclusion in future service packs:

- The fixes for the issues affecting Internet Explorer 6.0 will be included 
in Internet Explorer 6.0 Service Pack 2. 
- The fixes for the issues affecting Internet Explorer 5.01 Service Pack 2 
and Service Pack 3 will be included in Windows 2000 Service Pack 4. 

Reboot needed: Yes 

Patch can be uninstalled: No 

Superseded patches: This patch supersedes the one provided in Microsoft 
Security Bulletin MS02-047, 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 Q328970 
is listed in the Update Versions field. 
- To verify the individual files, use the patch manifest provided in 
Knowledge Base article Q328970. 


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 
Other information: 


Microsoft thanks  eEye Digital Security for reporting the malformed PNG 
issue to us and working with us to protect customers. 


Microsoft Knowledge Base article Q328970 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. 

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. 


V1.0 (November 20, 2002): Bulletin Created. 

[***** End Microsoft Security Bulletin MS02-066 *****]

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
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This document was prepared as an account of work sponsored by an
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