[NT] Vulnerabilities in Microsoft XML Core Services Allows Code Execution (MS06-061)

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Vulnerabilities in Microsoft XML Core Services Allows Code Execution
(MS06-061)
------------------------------------------------------------------------


SUMMARY

Two vulnerabilities were discovered in Microsoft XML Core Services that
allow a remote attacker to trigger a code execution vulnerability in a
client viewing a specially crafted XML file.

DETAILS

Affected Software:
* Microsoft XML Parser 2.6 (all versions) and Microsoft XML Core Services
3.0 (all versions) on Windows 2000 Service Pack 4 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=f9d16d74-1785-4c33-b1fc-df5258dd1089> Download the update (KB924191)
* Microsoft XML Parser 2.6 (all versions) and Microsoft XML Core Services
3.0 (all versions) on Microsoft Windows XP Service Pack 1 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=8a455c3b-213c-4395-87e9-9895f2b9a6ed> Download the update (KB924191)
* Microsoft XML Parser 2.6 (all versions) and Microsoft XML Core Services
3.0 (all versions) on Microsoft Windows XP Service Pack 2 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=8a455c3b-213c-4395-87e9-9895f2b9a6ed> Download the update (KB924191)
* Microsoft XML Parser 2.6 (all versions) and Microsoft XML Core Services
3.0 (all versions) on Microsoft Windows XP Professional x64 Edition -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=5593333f-bcd5-4750-a23d-4f7fccda6493> Download the update (KB924191)
* Microsoft XML Parser 2.6 (all versions) and Microsoft XML Core Services
3.0 (all versions) on Microsoft Windows Server 2003 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=09b77b2a-a4fd-46e2-af15-2385790c9ee7> Download the update (KB924191)
* Microsoft XML Parser 2.6 (all versions) and Microsoft XML Core Services
3.0 (all versions) on Microsoft Windows Server 2003 Service Pack 1 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=09b77b2a-a4fd-46e2-af15-2385790c9ee7> Download the update (KB924191)
* Microsoft XML Parser 2.6 (all versions) and Microsoft XML Core Services
3.0 (all versions) on Microsoft Windows Server 2003 for Itanium-based
Systems and Microsoft Windows Server 2003 with SP1 for Itanium-based
Systems Download the update (KB924191)
* Microsoft XML Parser 2.6 (all versions) and Microsoft XML Core Services
3.0 (all versions) on Microsoft Windows Server 2003 x64 Edition -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=31c88513-29df-475b-b9ae-a2f5c1f32a8c> Download the update (KB924191)
* Microsoft Office 2003 Service Pack 1 or Service Pack 2 with Microsoft
XML Core Services 5.0 Service Pack 1 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=8A37C111-D8E9-4C2E-9674-169B3331491C> Download the update (KB924424)

Non-Affected Software:
* Microsoft Windows 2000 Service Pack 4 running Microsoft XML Core
Services 2.5
* Microsoft Windows XP Service Pack 1 running Microsoft XML Core Services
2.5
* Microsoft Windows XP Service Pack 2 running Microsoft XML Core Services
2.5
* Microsoft Windows Server 2003 running Microsoft XML Core Services 2.5
* Microsoft Windows Server 2003 Service Pack 1 running Microsoft XML Core
Services 2.5

Affected Components:
* Microsoft XML Core Services 4.0 when installed on Windows 2000 Service
Pack 4 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=961f3c95-ec4e-4561-ab27-b3180e9139c5> Download the update (KB925672)
* Microsoft XML Core Services 4.0 when installed on Microsoft Windows XP
Service Pack 1 and Microsoft Windows XP Service Pack 2 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=961f3c95-ec4e-4561-ab27-b3180e9139c5> Download the update (KB925672)
* Microsoft XML Core Services 4.0 when installed on Microsoft Windows
Server 2003 and Microsoft Windows Server 2003 Service Pack 1 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=961f3c95-ec4e-4561-ab27-b3180e9139c5> Download the update (KB925672)
* Microsoft XML Core Services 6.0 when installed on Windows 2000 Service
Pack 4 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=fd513435-fa6d-407c-bedc-5fd03e5b7d6c> Download the update (KB925673)
* Microsoft XML Core Services 6.0 when installed on Microsoft Windows XP
Service Pack 1 and Microsoft Windows XP Service Pack 2 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=fd513435-fa6d-407c-bedc-5fd03e5b7d6c> Download the update (KB925673)
* Microsoft XML Core Services 6.0 when installed on Microsoft Windows
Server 2003 and Microsoft Windows Server 2003 Service Pack 1 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=fd513435-fa6d-407c-bedc-5fd03e5b7d6c> Download the update (KB925673)

Note: The security updates for Microsoft Windows Server 2003, Windows
Server 2003 Service Pack 1, and Windows Server 2003 x64 Edition also apply
to Windows Server 2003 R2.

Microsoft XML Core Services Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4685>
CVE-2006-4685:
A vulnerability exists in Microsoft XML Core Services that could allow for
information disclosure because the XMLHTTP ActiveX control incorrectly
interprets an HTTP server-side redirect. An attacker could exploit the
vulnerability by constructing a specially crafted Web page that could
potentially lead to information disclosure if a user visited that page or
clicked a link in a specially crafted e-mail message. An attacker who
successfully exploited this vulnerability could access content from
another domain retrieved using the credentials of the user browsing the
Web at the client. In addition, compromised Web sites and Web sites that
accept or host user-provided content or advertisements could contain
specially crafted content that could exploit this vulnerability. However,
user interaction is required to exploit this vulnerability.

Mitigating Factors for Microsoft XML Core Services Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4685>
CVE-2006-4685:
* In a Web-based attack scenario, an attacker would have to host a Web
site that contains a Web page that is used to exploit this vulnerability.
An attacker would have no way to force users to visit the page. Instead,
an attacker would have to persuade users to visit the Web site, typically
by getting them to click a link in an e-mail message or instant messenger
message that takes users to the attacker's Web site.

* By default, Internet Explorer on Windows Server 2003 runs in a
restricted mode that is known as
<http://msdn.microsoft.com/library/default.asp?url=/workshop/security/szone/overview/esc_changes.asp> Enhanced Security Configuration. This mode mitigates this vulnerability from sites that are not explicitly allowed to run script and ActiveX controls. See the FAQ section of this security update for more information about Internet Explorer Enhanced Security Configuration.

Workarounds for Microsoft XML Core Services Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4685>
CVE-2006-4685:
* Set Internet and Local intranet security zone settings to High to
prompt before running ActiveX controls and active scripting in the
Internet zone and in the Local intranet zone.

You can help protect against this vulnerability by changing your settings
for the Internet security zone to prompt before running ActiveX controls
and active scripting. You can do this by setting your browser security to
High.

To raise the browsing security level in Microsoft Internet Explorer:
1. On the Internet Explorer Tools menu, click Internet Options.
2. In the Internet Options dialog box, click the Security tab, and then
click the Internet icon.
3. Under Security level for this zone, move the slider to High. This sets
the security level for all Web sites you visit to High.

Note If no slider is visible, click Default Level, and then move the
slider to High.

Note Setting the level to High may cause some Web sites to work
incorrectly. If you have difficulty using a Web site after you change this
setting, and you are sure the site is safe to use, you can add that site
to your list of trusted sites. This will allow the site to work correctly
even with the high security setting.

Alternatively, you can change you settings to prompt before running
ActiveX controls only by following these steps:
1. In Internet Explorer, click Internet Options on the Tools menu.
2. Click the Security tab.
3. Click Internet, and then click Custom Level.
4. Under Settings, in the ActiveX controls and plug-ins section, under Run
ActiveX controls and plug-ins, click Prompt.
5. In the Scripting section, under Active Scripting, click Prompt, and
then click OK.
6. Click Local intranet, and then click Custom Level.
7. Under Settings, in the ActiveX controls and plug-ins section, under Run
ActiveX controls and plug-ins, click Prompt.
8. In the Scripting section, under Active Scripting, click Prompt.
9. Click OK two times to return to Internet Explorer.

Impact of Workaround: There are side effects to prompting before running
ActiveX controls. Many Web sites that are on the Internet or on an
intranet use ActiveX to provide additional functionality. For example, an
online e-commerce site or banking site may use ActiveX controls to provide
menus, ordering forms, or even account statements. Prompting before
running ActiveX controls is a global setting that affects all Internet and
intranet sites. You will be prompted frequently when you enable this
workaround. For each prompt, if you feel you trust the site that you are
visiting, click Yes to run ActiveX controls. If you do not want to be
prompted for all these sites, use the "Restrict Web sites to only your
trusted Web sites" workaround.

FAQ for Microsoft XML Core Services Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4685>
CVE-2006-4685:
What is the scope of the vulnerability?
This is an information disclosure vulnerability. An attacker could exploit
the vulnerability by constructing a specially crafted Web page that could
potentially lead to information disclosure if a user visited that page or
clicked a link in a specially crafted e-mail message. An attacker who
successfully exploited this vulnerability could access content from
another domain retrieved using the credentials of the user browsing the
Web at the client. However, user interaction is required to exploit this
vulnerability.

What causes the vulnerability?
A flaw exists in how the XMLHTTP control applies IE security settings to a
redirected data stream returned in response to a request for data from a
Web site.

What is Microsoft XML Core Services (MSXML)?
Microsoft XML Core Services (MSXML) allows customers who use JScript,
Visual Basic Scripting Edition (VBScript), and Microsoft Visual Studio 6.0
to build high-performance XML-based applications that provide a high
degree of interoperability with other applications that adhere to the XML
1.0 standard. See the MSDN Web site for more information regarding MSXML.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could read
cookies or other data from another security zone or domain in Internet
Explorer.

Who could exploit the vulnerability?
An attacker could host a specially crafted Web site that is designed to
exploit this vulnerability through Internet Explorer and then persuade a
user to view the Web site. This can also include Web sites that accept
user-provided content or advertisements, Web sites that host user-provided
content or advertisements, and compromised Web sites. These Web sites
could contain specially crafted content that could exploit this
vulnerability. In all cases, however, an attacker would have no way to
force users to visit these Web sites. Instead, an attacker would have to
persuade users to visit the Web site, typically by getting them to click a
link in an e-mail message or in an Instant Messenger request that takes
users to the attacker's Web site. It could also be possible to display
specially crafted Web content by using banner advertisements or by using
other methods to deliver Web content to affected systems.

What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user is logged on and visits a Web site
for any malicious action to occur. Therefore, any systems where Internet
Explorer is used frequently, such as workstations or terminal servers, are
at the most risk from this vulnerability. Systems that are not typically
used to visit Web sites, such as most server systems, are at a reduced
risk.

What is the Internet Explorer Enhanced Security Configuration?
Internet Explorer Enhanced Security Configuration is a group of
preconfigured Internet Explorer settings that reduce the likelihood of a
user or of an administrator downloading and running specially crafted Web
content on a server. Internet Explorer Enhanced Security Configuration
reduces this risk by modifying many security-related settings. This
includes the settings on the Security tab and the Advanced tab in the
Internet Options dialog box. Some of the important modifications include
the following:

* Security level for the Internet zone is set to High. This setting
disables scripts, ActiveX controls, Microsoft Java Virtual Machine
(MSJVM), and file downloads.

* Automatic detection of intranet sites is disabled. This setting assigns
all intranet Web sites and all Universal Naming Convention (UNC) paths
that are not explicitly listed in the Local intranet zone to the Internet
zone.

* Install On Demand and non-Microsoft browser extensions are disabled.
This setting prevents Web pages from automatically installing components
and prevents non-Microsoft extensions from running.

* Multimedia content is disabled. This setting prevents music,
animations, and video clips from running.

For more information regarding Internet Explorer Enhanced Security
Configuration, see the guide, Managing Internet Explorer Enhanced Security
Configuration, at the following Web site.

What does the update do?
The update removes the vulnerability by correcting the behavior of XML
Core Services. XML Core Services will now interpret a server-side redirect
in the XMLHTTP control differently and abort properly in previously
unhandled circumstances.

When this security bulletin was issued, had this vulnerability been
publicly disclosed?
No. Microsoft received information about this vulnerability through
responsible disclosure. Microsoft had not received any information to
indicate that this vulnerability had been publicly disclosed when this
security bulletin was originally issued.

XSLT Buffer Overrun Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4686>
CVE-2006-4686:
A vulnerability exists in XSLT processing that could allow remote code
execution on an affected system. An attacker could exploit the
vulnerability by constructing a malicious Web page that could potentially
allow remote code execution if a user visited that page. An attacker who
successfully exploited this vulnerability could take complete control of
an affected system.

Mitigating Factors for XSLT Buffer Overrun Vulnerability - XSLT Buffer
Overrun Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4686>
CVE-2006-4686:
* In a Web-based attack scenario, an attacker would have to host a Web
site that contains a Web page that is used to exploit this vulnerability.
An attacker would have no way to force users to visit that page. Instead,
an attacker would have to persuade users to visit the Web site, typically
by getting them to click a link in an e-mail message or instant messenger
message that takes users to the attacker's Web site.

* An attacker who successfully exploited this vulnerability could gain
the same user rights as the local user. Users whose accounts are
configured to have fewer user rights on the system could be less impacted
than users who operate with administrative user rights.

XSLT Buffer Overrun Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4686>
CVE-2006-4686:
FAQ for XSLT Buffer Overrun Vulnerability - CVE-2006-4686:

What is the scope of the vulnerability?
This is a vulnerability that could allow remote code execution. An
attacker could exploit the vulnerability by constructing a specially
crafted Web page that could potentially lead to remote code execution if a
user visited that page or clicked a link in a specially crafted e-mail
message. If a user is logged on with administrative user rights, an
attacker who successfully exploited this vulnerability could take complete
control of an affected system. An attacker could then install programs;
view, change, or delete data; or create new accounts with full user
rights. Users whose accounts are configured to have fewer user rights on
the system could be less impacted than users who operate with
administrative user rights.

What causes the vulnerability?
A vulnerability in a string buffer, within the XSLT control within MSXML.

What is XSLT?
Extensible Style*** Language Transformations (XSLT) is used to
manipulate XML data or extract content that needs to be reused.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could take
complete control of the affected system.

How could an attacker exploit the vulnerability?
An attacker could host a specially crafted Web site that is designed to
exploit this vulnerability through Internet Explorer and then persuade a
user to view the Web site. This can also include Web sites that accept
user-provided content or advertisements, Web sites that host user-provided
content or advertisements, and compromised Web sites. These Web sites
could contain specially crafted content that could exploit this
vulnerability. In all cases, however, an attacker would have no way to
force users to visit these Web sites. Instead, an attacker would have to
persuade users to visit the Web site, typically by getting them to click a
link in an e-mail message or in an Instant Messenger request that takes
users to the attacker's Web site. It could also be possible to display
specially crafted Web content by using banner advertisements or by using
other methods to deliver Web content to affected systems.

What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user is logged on and visits a Web site
for any malicious action to occur. Therefore, any systems where Internet
Explorer is used frequently, such as workstations or terminal servers, are
at the most risk from this vulnerability. Systems that are not typically
used to visit Web sites, such as most server systems, are at a reduced
risk.

What is the Internet Explorer Enhanced Security Configuration?
Internet Explorer
<http://msdn.microsoft.com/library/default.asp?url=/workshop/security/szone/overview/esc_changes.asp> Enhanced Security Configuration is a group of preconfigured Internet Explorer settings that reduce the likelihood of a user or of an administrator downloading and running specially crafted Web content on a server. Internet Explorer Enhanced Security Configuration reduces this risk by modifying many security-related settings. This includes the settings on the Security tab and the Advanced tab in the Internet Options dialog box. Some of the important modifications include the following:

* Security level for the Internet zone is set to High. This setting
disables scripts, ActiveX controls, Microsoft Java Virtual Machine
(MSJVM), and file downloads.

* Automatic detection of intranet sites is disabled. This setting assigns
all intranet Web sites and all Universal Naming Convention (UNC) paths
that are not explicitly listed in the Local intranet zone to the Internet
zone.

* Install On Demand and non-Microsoft browser extensions are disabled.
This setting prevents Web pages from automatically installing components
and prevents non-Microsoft extensions from running.

* Multimedia content is disabled. This setting prevents music,
animations, and video clips from running.

For more information regarding Internet Explorer Enhanced Security
Configuration, see the guide, Managing Internet Explorer Enhanced Security
Configuration, at the following
<http://www.microsoft.com/downloads/details.aspx?FamilyID=d41b036c-e2e1-4960-99bb-9757f7e9e31b&DisplayLang=en> Web site.

What does the update do?
The update removes the vulnerability by correcting the issue within the
affected string buffer.

When this security bulletin was issued, had this vulnerability been
publicly disclosed?
No. Microsoft received information about this vulnerability through
responsible disclosure. Microsoft had not received any information to
indicate that this vulnerability had been publicly disclosed when this
security bulletin was originally issued.


ADDITIONAL INFORMATION

The information has been provided by Microsoft Security Bulletin.
The original article can be found at:
<http://www.microsoft.com/technet/security/bulletin/ms06-061.mspx>
http://www.microsoft.com/technet/security/bulletin/ms06-061.mspx



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