[NT] Cumulative Security Update for Internet Explorer (MS06-021)

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• From: SecuriTeam <support@xxxxxxxxxxxxxx>
• Date: 14 Jun 2006 12:15:46 +0200

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Cumulative Security Update for Internet Explorer (MS06-021)
------------------------------------------------------------------------


SUMMARY

Improper memory and user input handling with Internet Explorer allows
attackers to execute arbitrary code and retrieve information.

DETAILS

Vulnerable Systems:
* Microsoft Windows 2000 Service Pack 4
* Microsoft Windows XP Service Pack 1 and Microsoft Windows XP Service
Pack 2
* Microsoft Windows XP Professional x64 Edition
* Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service
Pack 1
* Microsoft Windows Server 2003 for Itanium-based Systems and Microsoft
Windows Server 2003 with SP1 for Itanium-based Systems
* Microsoft Windows Server 2003 x64 Edition
* Microsoft Windows 98, Microsoft Windows 98 Second Edition (SE), and
Microsoft Windows Millennium Edition (Me) Review the FAQ section of this
bulletin for details about these operating systems.

* Internet Explorer 5.01 Service Pack 4 on Microsoft Windows 2000 Service
Pack 4
<http://www.microsoft.com/downloads/details.aspx?FamilyId=91A997DE-BAE4-4AC7-912D-79EF8ABAEF4F> Download the update
* Internet Explorer 6 Service Pack 1 on Microsoft Windows 2000 Service
Pack 4 or on Microsoft Windows XP Service Pack 1
<http://www.microsoft.com/downloads/details.aspx?FamilyId=0EB17A41-FB43-413B-A5CC-41E1F3DEDE4F> Download the update
* Internet Explorer 6 for Microsoft Windows XP Service Pack 2
<http://www.microsoft.com/downloads/details.aspx?FamilyId=85CABE87-C4A0-4F80-BD1C-210E23FD8D81> Download the update
* Internet Explorer 6 for Microsoft Windows Server 2003 and Microsoft
Windows Server 2003 Service Pack 1
<http://www.microsoft.com/downloads/details.aspx?FamilyId=CCE7C875-C9A4-4C3D-A37B-946EE5E781E7> Download the update
* Internet Explorer 6 for Microsoft Windows Server 2003 for Itanium-based
Systems and Microsoft Windows Server 2003 with SP1 for Itanium-based
Systems
<http://www.microsoft.com/downloads/details.aspx?FamilyId=C8E4CFB6-1350-4AAE-B681-EE2ECAB41118> Download the update
* Internet Explorer 6 for Microsoft Windows Server 2003 x64 Edition
<http://www.microsoft.com/downloads/details.aspx?FamilyId=1C7D5C6D-DDCF-485D-A1E3-60E55334FD74> Download the update
* Internet Explorer 6 for Microsoft Windows XP Professional x64 Edition

<http://www.microsoft.com/downloads/details.aspx?FamilyId=F91791AC-8185-4346-AA66-89F74D4B5EA7> Download the update
* Internet Explorer 6 Service Pack 1 on Microsoft Windows 98, on
Microsoft Windows 98 SE, or on Microsoft Windows Millennium Edition
Review the FAQ section of this bulletin for details about this version.

Exception Handling Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2218>
CVE-2006-2218:
A remote code execution vulnerability exists in the way Internet Explorer
handles exceptional conditions. As a result, system memory may be
corrupted in such a way that an attacker could execute arbitrary code if a
user visited a specially crafted Web site. An attacker who successfully
exploited this vulnerability could take complete control of an affected
system.

Mitigating Factors for Exception Handling Memory Corruption Vulnerability
- <http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2218>
CVE-2006-2218:
* In a Web-based attack scenario, an attacker could host a Web site that
contains a Web page that is used to exploit this vulnerability. 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. 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 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.

* The Restricted sites zone helps reduce attacks that could try to
exploit this vulnerability by preventing Active Scripting from being used
when reading HTML e-mail messages. However, if a user clicks a link in an
e-mail message, they user could still be vulnerable to this issue through
the Web-based attack scenario.

By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML
e-mail messages in the Restricted sites zone. Additionally Outlook 2000
opens HTML e-mail messages in the Restricted sites zone if the
<http://go.microsoft.com/fwlink/?LinkId=33334> Outlook E-mail Security
Update has been installed. Outlook Express 5.5 Service Pack 2 opens HTML
e-mail messages in the Restricted sites zone if
<http://go.microsoft.com/fwlink/?LinkId=19527> Microsoft Security Bulletin
MS04-018 has been installed.

Note While it cannot be ruled out that this vulnerability could be used in
an exploit without Active Scripting, it significantly increases the
chances of a successful exploit. As a result, this vulnerability has been
given a severity rating of Critical.

* 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 in the e-mail vector because reading e-mail messages in plain text is the default configuration for Outlook Express. See the FAQ section for this security update for more information about Internet Explorer Enhanced Security Configuration.

Workarounds for Exception Handling Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2218>
CVE-2006-2218:
Microsoft has tested the following workarounds. While these workarounds
will not correct the underlying vulnerability, they help block known
attack vectors. When a workaround reduces functionality, it is identified
in the following section.

Note While it cannot be ruled out that this vulnerability could be used in
an exploit without Active Scripting, it significantly increases the
chances of a successful exploit. As a result, this vulnerability has been
given a severity rating of Critical.

* Configure Internet Explorer to prompt before running Active Scripting
or to disable Active Scripting in the Internet and Local intranet security
zone

You can help protect against this vulnerability by changing your settings
to prompt before running Active Scripting or to disable Active Scripting
in the Internet and Local intranet security zone. To do this, follow 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 Scripting section, under Active Scripting,
click Prompt or Disable, and then click OK.
5. Click Local intranet, and then click Custom Level.
6. Under Settings, in the Scripting section, under Active Scripting,
click Prompt or Disable, and then click OK.
7. Click OK two times to return to Internet Explorer.

Note Disabling Active Scripting in the Internet and Local intranet
security zones 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.

Impact of Workaround: There are side effects to prompting before running
Active Scripting. Many Web sites that are on the Internet or on an
intranet use Active Scripting to provide additional functionality. For
example, an online e-commerce site or banking site may use Active
Scripting to provide menus, ordering forms, or even account statements.
Prompting before running Active Scripting 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 Active Scripting. If you do not
want to be prompted for all these sites, use the steps outlined in "Add
sites that you trust to the Internet Explorer Trusted sites zone .

Add sites that you trust to the Internet Explorer Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX
controls and Active Scripting in the Internet zone and in the Local
intranet zone, you can add sites that you trust to the Internet Explorer
Trusted sites zone. This will allow you to continue to use trusted Web
sites exactly as you do today, while helping to protect you from this
attack on untrusted sites. We recommend that you add only sites that you
trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then
click the Security tab.
2. In the Select a Web content zone to specify its current security
settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel,
click to clear the Require server verification (https:) for all sites in
this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that
you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet
Explorer.

Note Add any sites that you trust not to take malicious action on your
computer. Two in particular that you may want to add are
"*.windowsupdate.microsoft.com" and *.update.microsoft.com (without the
quotation marks). These are the sites that will host the update, and it
requires an ActiveX Control to install the update.

* Set Internet and Local intranet security zone settings to High to
prompt before running ActiveX Controls and Active Scripting in these zones

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,
follow these steps:

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 security setting set to High.

Impact of Workaround: There are side effects to prompting before running
ActiveX Controls and Active Scripting. Many Web sites that are on the
Internet or on an intranet use ActiveX or Active Scripting 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 or
Active Scripting 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 or Active Scripting. If you do
not want to be prompted for all these sites, use the steps outlined in
"Add sites that you trust to the Internet Explorer Trusted sites zone

Add sites that you trust to the Internet Explorer Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX
controls and Active Scripting in the Internet zone and in the Local
intranet zone, you can add sites that you trust to the Internet Explorer
Trusted sites zone. This will allow you to continue to use trusted Web
sites exactly as you do today, while helping to protect you from this
attack on untrusted sites. We recommend that you add only sites that you
trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then
click the Security tab.
2. In the Select a Web content zone to specify its current security
settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel,
click to clear the Require server verification (https:) for all sites in
this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that
you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet
Explorer.

Note Add any sites that you trust not to take malicious action on your
computer. Two in particular that you may want to add are
"*.windowsupdate.microsoft.com" and *.update.microsoft.com (without the
quotation marks). These are the sites that will host the update, and it
requires an ActiveX Control to install the update.

FAQ for Exception Handling Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2218>
CVE-2006-2218:
What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who
successfully exploited this vulnerability could remotely 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.

What causes the vulnerability?
Internet Explorer allows objects to register exception handlers that may
not properly handle certain conditions. Unsafe exception handling can
cause memory corruption resulting in remote code execution.

What might an attacker use the vulnerability to do?
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.

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 or
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.

Could this vulnerability be exploited through e-mail?
This vulnerability could not be exploited automatically through e-mail or
while viewing e-mail messages in the preview pane while using Outlook or
Outlook Express. Customers would have to click a link that would take them
to a specially crafted Web site, or open an attachment that could exploit
the vulnerability.

What systems are primarily at risk from the vulnerability?
This vulnerability requires a user to be logged on and visiting 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.

What does the update do?
The update removes the vulnerability by changing the way that Internet
Explorer does exception handling. Specifically, exception handlers are
removed from Internet Explorer with this update. These exception handlers
were previously removed from Internet Explorer 7 and Windows Vista.

What might the removal of these exception handlers result in?
With the removal of these exception handlers, exceptions from objects that
do not handle their own exception, which were previously caught within the
Internet Explorer process may now result in application faults. These
application faults could cause Internet Explorer to fail. The object or
software where the application fault occurs now needs to either address
the cause of the application fault or handle its own exception.

What can I do to prevent these application faults?
<http://go.microsoft.com/fwlink/?LinkId=66975> Microsoft Security
Bulletin MS06-023: Vulnerability in Microsoft JScript Could Allow Remote
Code Execution (917344) addresses the cause of the application fault in
JScript. Other objects, software, or Web application where application
faults may occur as a result of the changes made in Microsoft security
bulletin MS06-021 now needs to either address the cause of the application
fault or handle its own exception.

What is exception handling and how can I implement it?
Robust code anticipates and handles exceptions. Exceptions occur when a
program executes abnormally because of conditions outside the program's
control. Certain operations, including object creation and file
input/output, are subject to failures that go beyond errors. Out-of-memory
conditions, for example, can occur even when your program is running
correctly. For more information about exception handling see the product
documentation:

<http://msdn2.microsoft.com/en-us/library/x057540h.aspx> Exception
handling in Visual C++

<http://msdn2.microsoft.com/en-US/library/s6da8809.aspx> Exception
handling in Visual Basic

<http://msdn2.microsoft.com/en-us/library/ms229005.aspx> Exception
handling in the .NET Framework

When this security bulletin was issued, had this vulnerability been
publicly disclosed?
No. Microsoft received information about this vulnerability through
responsible disclosure.

Note This security update also includes updates for an application fault
reported in to us through Microsoft Error Reporting Service. We actively
analyze all error reports and prioritize them based on the number of
customers affected by the application fault covered in the error report.
This application fault is the same as the application fault called out in
the public report of the non-exploitable variant of the vulnerability
addressed in this security bulletin as Exception Handling Memory
Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2218>
CVE-2006-2218 .

This application fault has been discussed as
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-1992>
CVE-2006-1992 and a subsequent public post also discussed the exception
handling aspect. It is important to note that the application fault in and
of itself only will cause Internet Explorer to fail, the vulnerability
addressed in this security bulletin must be used for an exploit to occur.

When this security bulletin was issued, had Microsoft received any reports
that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this
vulnerability had been publicly used to attack customers and had not seen
any examples of proof of concept code published when this security
bulletin was originally issued.

HTML Decoding Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2382>
CVE-2006-2382:
A remote code execution vulnerability exists in the way Internet Explorer
decodes specially crafted UTF-8 encoded HTML. An attacker could exploit
the vulnerability by constructing a specially crafted Web page that could
potentially allow remote code execution if a user visited the specially
crafted Web site. An attacker who successfully exploited this
vulnerability could take complete control of an affected system.

Mitigating Factors for HTML Decoding Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2382>
CVE-2006-2382:
* In a Web-based attack scenario, an attacker could host a Web site that
contains a Web page that is used to exploit this vulnerability. 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. 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 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.

* 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 in the e-mail vector because reading e-mail messages in plain text is the default configuration for Outlook Express. See the FAQ section of this security update for more information about Internet Explorer Enhanced Security Configuration.

Workarounds for HTML Decoding Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2382>
CVE-2006-2382:
Microsoft has tested the following workarounds. Although these workarounds
will not correct the underlying vulnerability, they help block known
attack vectors. When a workaround reduces functionality, it is identified
in the following section.

* Read e-mail messages in plain text format if you are using Outlook 2002
or a later version, or Outlook Express 6 SP1 or a later version, to help
protect yourself from the HTML e-mail attack vector.

Microsoft Outlook 2002 users who have applied Office XP Service Pack 1 or
a later version and Microsoft Outlook Express 6 users who have applied
Internet Explorer 6 Service Pack 1 or a later version can enable this
setting and view e-mail messages that are not digitally signed or e-mail
messages that are not encrypted in plain text only.

Digitally signed e-mail messages or encrypted e-mail messages are not
affected by the setting and may be read in their original formats. For
more information about how to enable this setting in Outlook 2002, see
<http://support.microsoft.com/kb/307594> Microsoft Knowledge Base Article
307594.

For information about this setting in Outlook Express 6, see
<http://support.microsoft.com/kb/291387> Microsoft Knowledge Base Article
291387.

Impact of Workaround: E-mail messages that are viewed in plain text format
will not contain pictures, specialized fonts, animations, or other rich
content. Additionally:

*The changes are applied to the preview pane and to open messages.
*Pictures become attachments so that they are not lost.
*Because the message is still in Rich Text or HTML format in the store,
the object model (custom code solutions) may behave unexpectedly.

FAQ for HTML Decoding Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2382>
CVE-2006-2382:
What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who
successfully exploited this vulnerability could remotely 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.

What causes the vulnerability?
When Internet Explorer handles specially crafted UTF-8 encoded HTML it may
corrupt system memory in such a way that an attacker could execute
arbitrary code.

What might an attacker use the vulnerability to do?
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.

How could an attacker exploit the vulnerability?
An attacker could host a specially crafted Web site or HTML e-mail message
that is designed to exploit this vulnerability through Internet Explorer
and then persuade a user to view the Web site or HTML e-mail message. 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 reading HTML
e-mail messages or that a user is logged on and visits a Web site for any
malicious action to occur. Therefore, any systems where HTML e-mail
messages are read or where Internet Explorer is used frequently, such as
workstations or terminal servers, are at the most risk from this
vulnerability.

What does the update do?
The update removes the vulnerability by modifying the way that Internet
Explorer decodes UTF-8 encoded HTML.

When this security bulletin was issued, had this vulnerability been
publicly disclosed?
No. Microsoft received information about this vulnerability through
responsible disclosure.

When this security bulletin was issued, had Microsoft received any reports
that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this
vulnerability had been publicly used to attack customers and had not seen
any examples of proof of concept code published when this security
bulletin was originally issued.

ActiveX Control Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2383>
CVE-2006-2383:
A remote code execution vulnerability exists in the
DXImageTransform.Microsoft.Light ActiveX control if passed unexpected
data. An attacker could exploit the vulnerability by constructing a
specially crafted Web page that could potentially allow remote code
execution if a user visited the specially crafted Web site. An attacker
who successfully exploited this vulnerability could take complete control
of an affected system.

Mitigating Factors for ActiveX Control Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2383>
CVE-2006-2383:
* In a Web-based attack scenario, an attacker could host a Web site that
contains a Web page that is used to exploit this vulnerability. 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. 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 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.

* The Restricted sites zone helps reduce attacks that could try to
exploit this vulnerability by preventing ActiveX Controls from being used
when reading HTML e-mail messages. However, if a user clicks a link in an
e-mail message, the use could still be vulnerable to this issue through
the Web-based attack scenario.

By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML
e-mail messages in the Restricted sites zone. Additionally Outlook 2000
opens HTML e-mail messages in the Restricted sites zone if the
<http://go.microsoft.com/fwlink/?LinkId=33334> Outlook E-mail Security
Update has been installed. Outlook Express 5.5 Service Pack 2 opens HTML
e-mail messages in the Restricted sites zone if
<http://go.microsoft.com/fwlink/?LinkId=19527> Microsoft Security Bulletin
MS04-018 has been installed.

* By default, Internet Explorer on Windows Server 2003 runs in a
restricted mode that is known as Enhanced Security Configuration. This
mode mitigates this vulnerability in the e-mail vector because reading
e-mail messages in plain text is the default configuration for Outlook
Express. See the FAQ section for this security update for more information
about Internet Explorer Enhanced Security Configuration.

Workarounds for ActiveX Control Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2383>
CVE-2006-2383:
Microsoft has tested the following workarounds. While these workarounds
will not correct the underlying vulnerability, they help block known
attack vectors. When a workaround reduces functionality, it is identified
in the following section.

* Configure Internet Explorer to prompt before running ActiveX Controls
or disable ActiveX Controls in the Internet and Local intranet security
zone

You can help protect against this vulnerability by changing your Internet
Explorer settings to prompt before running ActiveX controls. To do this,
follow 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 or Disable, and then click
OK.
5. Click Local intranet, and then click Custom Level.
6. Under Settings, in the ActiveX controls and plug-ins section, under
Run ActiveX controls and plug-ins, click Prompt or Disable, and then click
OK.
7. 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 steps outlined in "Add sites that
you trust to the Internet Explorer Trusted sites zone .

Add sites that you trust to the Internet Explorer Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX
controls and Active Scripting in the Internet zone and in the Local
intranet zone, you can add sites that you trust to the Internet Explorer
Trusted sites zone. This will allow you to continue to use trusted Web
sites exactly as you do today, while helping to protect you from this
attack on untrusted sites. We recommend that you add only sites that you
trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then
click the Security tab.
2. In the Select a Web content zone to specify its current security
settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel,
click to clear the Require server verification (https:) for all sites in
this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that
you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet
Explorer.

Note Add any sites that you trust not to take malicious action on your
computer. Two in particular that you may want to add are
"*.windowsupdate.microsoft.com" and *.update.microsoft.com (without the
quotation marks). These are the sites that will host the update, and it
requires an ActiveX Control to install the update.

* Set Internet and Local intranet security zone settings to High to
prompt before running ActiveX Controls and Active Scripting in these zones

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

To raise the browsing security level in Microsoft Internet Explorer,
follow these steps:

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 security setting set to High.

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 steps outlined in "Add sites that
you trust to the Internet Explorer Trusted sites zone .

Add sites that you trust to the Internet Explorer Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX
controls and Active Scripting in the Internet zone and in the Local
intranet zone, you can add sites that you trust to the Internet Explorer
Trusted sites zone. This will allow you to continue to use trusted Web
sites exactly as you do today, while helping to protect you from this
attack on untrusted sites. We recommend that you add only sites that you
trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then
click the Security tab.
2. In the Select a Web content zone to specify its current security
settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel,
click to clear the Require server verification (https:) for all sites in
this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that
you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet
Explorer.

Note Add any sites that you trust not to take malicious action on your
computer. Two in particular that you may want to add are
"*.windowsupdate.microsoft.com" and *.update.microsoft.com (without the
quotation marks). These are the sites that will host the update, and it
requires an ActiveX Control to install the update.

Prevent COM objects from running in Internet Explorer

You can disable attempts to instantiate a COM object in Internet Explorer
by setting the kill bit for the control in the registry.

Warning If you use Registry Editor incorrectly, you may cause serious
problems that may require you to reinstall your operating system.
Microsoft cannot guarantee that you can solve problems that result from
using Registry Editor incorrectly. Use Registry Editor at your own risk.

For detailed steps that you can use to prevent a control from running in
Internet Explorer, see <http://support.microsoft.com/kb/240797> Microsoft
Knowledge Base Article 240797. Follow these steps in this article to
create a Compatibility Flags value in the registry to prevent a COM object
from being instantiated in Internet Explorer.

To set the kill bit for the DXImageTransform.Microsoft.Light ActiveX
control, paste the following text in a text editor such as Notepad. Then,
save the file by using the .reg file name extension.

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX
Compatibility\{F9EFBEC2-4302-11D2-952A-00C04FA34F05}]
"Compatibility Flags"=dword:00000400

You can apply this .reg file to individual systems by double-clicking it.
You can also apply it across domains by using Group Policy. For more
information about Group Policy, visit the following Microsoft Web sites:


<http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/TechRef/6d7cb788-b31d-4d17-9f1e-b5ddaa6deecd.mspx> Group Policy collection


<http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/TechRef/47ba1311-6cca-414f-98c9-2d7f99fca8a3.mspx> What is Group Policy Object Editor?


<http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/TechRef/e926577a-5619-4912-b5d9-e73d4bdc9491.mspx> Core Group Policy tools and settings

Note You must restart Internet Explorer for your changes to take effect.

Impact of Workaround: The DXImageTransform.Microsoft.Light ActiveX control
is a static filter used to create the effect of a light shining on the
content of an object. This functionality would no longer be accessible for
software using this ActiveX control.

FAQ for ActiveX Control Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2383>
CVE-2006-2383:
What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who
successfully exploited this vulnerability could remotely 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.

What causes the vulnerability?
The DXImageTransform.Microsoft.Light ActiveX control could, if passed
unexpected data, cause Internet Explorer to fail in a way that could allow
code execution.

What might an attacker use the vulnerability to do?
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.

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.

What does the update do?
The update removes the vulnerability by modifying the way that Internet
Explorer performs parameter validation.

When this security bulletin was issued, had this vulnerability been
publicly disclosed?
No. Microsoft received information about this vulnerability through
responsible disclosure.

When this security bulletin was issued, had Microsoft received any reports
that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this
vulnerability had been publicly used to attack customers and had not seen
any examples of proof of concept code published when this security
bulletin was originally issued.

COM Object Instantiation Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-1303>
CVE-2006-1303:
A remote code execution vulnerability exists in the way Internet Explorer
instantiates COM objects that are not intended to be instantiated in
Internet Explorer. An attacker could exploit the vulnerability by
constructing a specially crafted Web page that could potentially allow
remote code execution if a user visited the specially crafted Web site. An
attacker who successfully exploited this vulnerability could take complete
control of an affected system.

Mitigating Factors for COM Object Instantiation Memory Corruption
Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-1303>
CVE-2006-1303:
* Customers who have installed the security update included with
<http://go.microsoft.com/fwlink/?LinkId=50690> Microsoft Security Bulletin
MS05-052 or a later security bulletin for Internet Explorer are not at
risk from attacks originating from the Internet zone.

* In a Web-based attack scenario, an attacker could host a Web site that
contains a Web page that is used to exploit this vulnerability. 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. 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 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.

* The Restricted sites zone helps reduce attacks that could try to
exploit this vulnerability by preventing ActiveX Controls from being used
when reading HTML e-mail messages. However, if a user clicks a link in an
e-mail message, they could still be vulnerable to this issue through the
Web-based attack scenario.

By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML
e-mail messages in the Restricted sites zone. Additionally Outlook 2000
opens HTML e-mail messages in the Restricted sites zone if the
<http://go.microsoft.com/fwlink/?LinkId=33334> Outlook E-mail Security
Update has been installed. Outlook Express 5.5 Service Pack 2 opens HTML
e-mail messages in the Restricted sites zone if
<http://go.microsoft.com/fwlink/?LinkId=19527> Microsoft Security Bulletin
MS04-018 has been installed.

* 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. See the FAQ section for this security update for more information about Internet Explorer Enhanced Security Configuration.

Workarounds for COM Object Instantiation Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-1303>
CVE-2006-1303:
Microsoft has tested the following workarounds. While these workarounds
will not correct the underlying vulnerability, they help block known
attack vectors. When a workaround reduces functionality, it is identified
in the following section.

Configure Internet Explorer to prompt before running ActiveX Controls or
disable ActiveX Controls in the Internet and Local intranet security zone

You can help protect against this vulnerability by changing your Internet
Explorer settings to prompt before running ActiveX controls. To do this,
follow 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 or Disable, and then click
OK.
5. Click Local intranet, and then click Custom Level.
6. Under Settings, in the ActiveX controls and plug-ins section, under
Run ActiveX controls and plug-ins, click Prompt or Disable, and then click
OK.
7. 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 steps outlined in "Add sites that
you trust to the Internet Explorer Trusted sites zone .

Add sites that you trust to the Internet Explorer Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX
controls and Active Scripting in the Internet zone and in the Local
intranet zone, you can add sites that you trust to the Internet Explorer
Trusted sites zone. This will allow you to continue to use trusted Web
sites exactly as you do today, while helping to protect you from this
attack on untrusted sites. We recommend that you add only sites that you
trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then
click the Security tab.
2. In the Select a Web content zone to specify its current security
settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel,
click to clear the Require server verification (https:) for all sites in
this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that
you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet
Explorer.

Note Add any sites that you trust not to take malicious action on your
computer. Two in particular that you may want to add are
"*.windowsupdate.microsoft.com" and *.update.microsoft.com (without the
quotation marks). These are the sites that will host the update, and it
requires an ActiveX Control to install the update.

* Set Internet and Local intranet security zone settings to High to
prompt before running ActiveX Controls and Active Scripting in these zones

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

To raise the browsing security level in Microsoft Internet Explorer,
follow these steps:

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 security setting set to High.

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 steps outlined in "Add sites that
you trust to the Internet Explorer Trusted sites zone .

Add sites that you trust to the Internet Explorer Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX
controls and Active Scripting in the Internet zone and in the Local
intranet zone, you can add sites that you trust to the Internet Explorer
Trusted sites zone. This will allow you to continue to use trusted Web
sites exactly as you do today, while helping to protect you from this
attack on untrusted sites. We recommend that you add only sites that you
trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then
click the Security tab.
2. In the Select a Web content zone to specify its current security
settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel,
click to clear the Require server verification (https:) for all sites in
this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that
you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet
Explorer.

Note Add any sites that you trust not to take malicious action on your
computer. Two in particular that you may want to add are
"*.windowsupdate.microsoft.com" and *.update.microsoft.com (without the
quotation marks). These are the sites that will host the update, and it
requires an ActiveX Control to install the update.

Prevent COM objects from running in Internet Explorer

You can disable attempts to instantiate a COM object in Internet Explorer
by setting the kill bit for the control in the registry.

Warning If you use Registry Editor incorrectly, you may cause serious
problems that may require you to reinstall your operating system.
Microsoft cannot guarantee that you can solve problems that result from
using Registry Editor incorrectly. Use Registry Editor at your own risk.

For detailed steps that you can use to prevent a control from running in
Internet Explorer, see <http://support.microsoft.com/kb/240797> Microsoft
Knowledge Base Article 240797. Follow these steps in this article to
create a Compatibility Flags value in the registry to prevent a COM object
from being instantiated in Internet Explorer.

For example, to set the kill bit for a CLSID in the Wmm2fxa.dll file that
is included in this security update, paste the following text in a text
editor such as Notepad. Then, save the file by using the .reg file name
extension.

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX
Compatibility\{B4DC8DD9-2CC1-4081-9B2B-20D7030234EF}]
"Compatibility Flags"=dword:00000400

You can apply this .reg file to individual systems by double-clicking it.
You can also apply it across domains by using Group Policy. For more
information about Group Policy, visit the following Microsoft Web sites:


<http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/TechRef/6d7cb788-b31d-4d17-9f1e-b5ddaa6deecd.mspx> Group Policy collection


<http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/TechRef/47ba1311-6cca-414f-98c9-2d7f99fca8a3.mspx> What is Group Policy Object Editor?


<http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/TechRef/e926577a-5619-4912-b5d9-e73d4bdc9491.mspx> Core Group Policy tools and settings

Note You must restart Internet Explorer for your changes to take effect.

Impact of Workaround: There is no impact as long as the COM object is not
intended to be used in Internet Explorer.

FAQ for COM Object Instantiation Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-1303>
CVE-2006-1303:
What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who
successfully exploited this vulnerability could remotely 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.

What causes the vulnerability?
When Internet Explorer tries to instantiate certain COM objects as ActiveX
Controls, the COM objects may corrupt the system state in such a way that
an attacker could execute arbitrary code.

What might an attacker use the vulnerability to do?
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.

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.

Note Customers who have installed the security update included with
<http://go.microsoft.com/fwlink/?LinkId=50690> Microsoft Security Bulletin
MS05-052 or a later security bulletin for Internet Explorer are not at
risk from attacks originating from the Internet zone.

What does the update do?
Because not all COM objects are designed to be accessed through Internet
Explorer, this update sets the <http://support.microsoft.com/kb/240797>
kill bit for a list of Class Identifiers (CLSIDs) for COM objects that
have been found to exhibit similar behavior to the COM object
Instantiation Memory Corruption Vulnerability that is addressed in
<http://go.microsoft.com/fwlink/?LinkId=53511> Microsoft Security Bulletin
MS05-054. To help protect customers, this update prevents these CLSIDs
from being instantiated in Internet Explorer. For more information about
kill bits, see <http://support.microsoft.com/kb/240797> Microsoft
Knowledge Base Article 240797.

The Class Identifiers and corresponding COM objects are as follows.

Class Identifier File
B4DC8DD9-2CC1-4081-9B2B-20D7030234EF Wmm2fxa.dll
C63344D8-70D3-4032-9B32-7A3CAD5091A5 Wmm2fxa.dll
353359C1-39E1-491b-9951-464FD8AB071C Wmm2fxa.dll

When this security bulletin was issued, had this vulnerability been
publicly disclosed?
No. Microsoft received information about this vulnerability through
responsible disclosure.

When this security bulletin was issued, had Microsoft received any reports
that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this
vulnerability had been publicly used to attack customers and had not seen
any examples of proof of concept code published when this security
bulletin was originally issued.

CSS Cross-Domain Information Disclosure Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2005-4089>
CVE-2005-4089:
An information disclosure vulnerability exists in Internet Explorer
because it incorrectly interprets a specially crafted document as a
cascading style sheet (CSS). An attacker could exploit the vulnerability
by constructing a specially crafted Web page that could potentially lead
to information disclosure if a user visited a specially crafted Web site
or clicked a link in a specially crafted e-mail message. An attacker who
successfully exploited this vulnerability could read file data from
another Internet Explorer domain. However, user interaction is required to
exploit this vulnerability.

Mitigating Factors for CSS Cross-Domain Information Disclosure
Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2005-4089>
CVE-2005-4089:
* 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 a specially crafted
Web site. Instead, an attacker would have to persuade them to visit the
Web site, typically by getting them to click a link that takes them to the
attacker's Web site.

* An attacker who successfully exploited this vulnerability could gain
access to file data from a system other than that of the attacker s Web
site.

* The Restricted sites zone helps reduce attacks that could try to
exploit this vulnerability by preventing Active Scripting from being used
when reading HTML e-mail messages. However, if a user clicks a link in an
e-mail message, they could still be vulnerable to this issue through the
Web-based attack scenario.

By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML
e-mail messages in the Restricted sites zone. Additionally Outlook 2000
opens HTML e-mail messages in the Restricted sites zone if the
<http://go.microsoft.com/fwlink/?LinkId=33334> Outlook E-mail Security
Update has been installed. Outlook Express 5.5 Service Pack 2 opens HTML
e-mail messages in the Restricted sites zone if
<http://go.microsoft.com/fwlink/?LinkId=19527> Microsoft Security Bulletin
MS04-018 has been installed.

* 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 in the e-mail vector because reading e-mail messages in plain text is the default configuration for Outlook Express. See the FAQ section of this security update for more information about Internet Explorer Enhanced Security Configuration.

Workarounds for CSS Cross-Domain Information Disclosure Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2005-4089>
CVE-2005-4089:
Microsoft has tested the following workarounds. While these workarounds
will not correct the underlying vulnerability, they help block known
attack vectors. When a workaround reduces functionality, it is identified
in the following section.

* Configure Internet Explorer to prompt before running Active Scripting
or disable Active Scripting in the Internet and Local intranet security
zone

You can help protect against this vulnerability by changing your settings
to prompt before running Active Scripting or to disable Active Scripting
in the Internet and Local intranet security zone. To do this, follow 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 Scripting section, under Active Scripting,
click Prompt or Disable, and then click OK.
5. Click Local intranet, and then click Custom Level.
6. Under Settings, in the Scripting section, under Active Scripting,
click Prompt or Disable, and then click OK.
7. Click OK two times to return to Internet Explorer.

Note Disabling Active Scripting in the Internet and Local intranet
security zones 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.

Impact of Workaround: There are side effects to prompting before running
Active Scripting. Many Web sites that are on the Internet or on an
intranet use Active Scripting to provide additional functionality. For
example, an online e-commerce site or banking site may use Active
Scripting to provide menus, ordering forms, or even account statements.
Prompting before running Active Scripting 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 Active Scripting. If you do not
want to be prompted for all these sites, use the steps outlined in "Add
sites that you trust to the Internet Explorer Trusted sites zone .

Add sites that you trust to the Internet Explorer Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX
controls and Active Scripting in the Internet zone and in the Local
intranet zone, you can add sites that you trust to the Internet Explorer
Trusted sites zone. This will allow you to continue to use trusted Web
sites exactly as you do today, while helping to protect you from this
attack on untrusted sites. We recommend that you add only sites that you
trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then
click the Security tab.
2. In the Select a Web content zone to specify its current security
settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel,
click to clear the Require server verification (https:) for all sites in
this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that
you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet
Explorer.

Note Add any sites that you trust not to take malicious action on your
computer. Two in particular that you may want to add are
"*.windowsupdate.microsoft.com" and *.update.microsoft.com (without the
quotation marks). These are the sites that will host the update, and it
requires an ActiveX Control to install the update.

* Set Internet and Local intranet security zone settings to High to
prompt before running ActiveX Controls and Active Scripting in these zones

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

To raise the browsing security level in Microsoft Internet Explorer,
follow these steps:

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 security setting set to High.

Impact of Workaround: There are side effects to prompting before running
ActiveX Controls and Active Scripting. Many Web sites that are on the
Internet or on an intranet use ActiveX or Active Scripting 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 or
Active Scripting 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 or Active Scripting. If you do
not want to be prompted for all these sites, use the steps outlined in
"Add sites that you trust to the Internet Explorer Trusted sites zone .

Add sites that you trust to the Internet Explorer Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX
controls and Active Scripting in the Internet zone and in the Local
intranet zone, you can add sites that you trust to the Internet Explorer
Trusted sites zone. This will allow you to continue to use trusted Web
sites exactly as you do today, while helping to protect you from this
attack on untrusted sites. We recommend that you add only sites that you
trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then
click the Security tab.
2. In the Select a Web content zone to specify its current security
settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel,
click to clear the Require server verification (https:) for all sites in
this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that
you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet
Explorer.

Note Add any sites that you trust not to take malicious action on your
computer. Two in particular that you may want to add are
"*.windowsupdate.microsoft.com" and *.update.microsoft.com (without the
quotation marks). These are the sites that will host the update, and it
requires an ActiveX Control to install the update.

FAQ for CSS Cross-Domain Information Disclosure Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2005-4089>
CVE-2005-4089:
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 a specially
crafted Web site. An attacker who successfully exploited this
vulnerability could read data from another Internet Explorer domain.
However, user interaction is required to exploit this vulnerability.

What causes the vulnerability?
Internet Explorer incorrectly interprets a specially crafted document as a
cascading style sheet (CSS).

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

What are Internet Explorer security zones?
Internet Explorer
<http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q174360> security
zones are part of a system that divides online content into categories or
zones, based on the trustworthiness of the content. Specific Web domains
can be assigned to a zone, depending on how much trust is put in the
content of each domain. The zone then restricts the capabilities of the
Web content, based on the zone's policy. By default, most Internet domains
are treated as part of the Internet zone. By default, the policy of the
Internet zone prevents scripts and other active code from accessing
resources on the local 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 a user to be logged on and visiting 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.

What does the update do?
The update removes the vulnerability by changing Internet Explorer so that
it correctly restricts cross-domain access to CSS text when a CSS file
type is not used to positively identify legitimate CSS content.

When this security bulletin was issued, had this vulnerability been
publicly disclosed?
Yes. This vulnerability has been publicly disclosed. It has been assigned
Common Vulnerability and Exposure number CVE-2005-4089.

When this security bulletin was issued, had Microsoft received any reports
that this vulnerability was being exploited?
No. Microsoft had seen examples of proof of concept code published
publicly but had not received any information to indicate that this
vulnerability had been publicly used to attack customers when this
security bulletin was originally issued.

Does applying this security update help protect customers from the code
that has been published publicly that attempts to exploit this
vulnerability?
Yes. This security update addresses the vulnerability that potentially
could be exploited by using the published proof of concept code. The
vulnerability that has been addressed has been assigned the Common
Vulnerability and Exposure number CVE-2005-4089.

Address Bar Spoofing Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2384>
CVE-2006-2384:
A spoofing vulnerability exists in Internet Explorer that could allow an
attacker to display spoofed content in a browser window. The address bar
and other parts of the trust UI can be displayed from trusted Web sites
but the content of the window contains the attacker s Web page.

Mitigating Factors for Address Bar Spoofing Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2384>
CVE-2006-2384:
* 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 a specially crafted
Web site. Instead, an attacker would have to persuade them to visit the
Web site, typically by getting them to click a link that takes them to the
attacker's Web site.

* The Restricted sites zone helps reduce attacks that could try to
exploit this vulnerability by preventing Active Scripting from being used
when reading HTML e-mail messages. However, if a user clicks a link in an
e-mail message, they could still be vulnerable to this issue through the
Web-based attack scenario.

By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML
e-mail messages in the Restricted sites zone. Additionally Outlook 2000
opens HTML e-mail messages in the Restricted sites zone if the
<http://go.microsoft.com/fwlink/?LinkId=33334> Outlook E-mail Security
Update has been installed. Outlook Express 5.5 Service Pack 2 opens HTML
e-mail messages in the Restricted sites zone if
<http://go.microsoft.com/fwlink/?LinkId=19527> Microsoft Security Bulletin
MS04-018 has been installed.

* 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. See the FAQ section or this security update for more information about Internet Explorer Enhanced Security Configuration.

Workarounds for Address Bar Spoofing Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2384>
CVE-2006-2384:
Microsoft has tested the following workarounds. While these workarounds
will not correct the underlying vulnerability, they help block known
attack vectors. When a workaround reduces functionality, it is identified
in the following section.

Configure Internet Explorer to prompt before running Active Scripting or
disable Active Scripting in the Internet and Local intranet security zone

You can help protect against this vulnerability by changing your settings
to prompt before running Active Scripting or to disable Active Scripting
in the Internet and Local intranet security zone. To do this, follow 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 Scripting section, under Active Scripting,
click Prompt or Disable, and then click OK.
5. Click Local intranet, and then click Custom Level.
6. Under Settings, in the Scripting section, under Active Scripting,
click Prompt or Disable, and then click OK.
7. Click OK two times to return to Internet Explorer.

Note Disabling Active Scripting in the Internet and Local intranet
security zones 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.

Impact of Workaround: There are side effects to prompting before running
Active Scripting. Many Web sites that are on the Internet or on an
intranet use Active Scripting to provide additional functionality. For
example, an online e-commerce site or banking site may use Active
Scripting to provide menus, ordering forms, or even account statements.
Prompting before running Active Scripting 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 Active Scripting. If you do not
want to be prompted for all these sites, use the steps outlined in "Add
sites that you trust to the Internet Explorer Trusted sites zone .

Add sites that you trust to the Internet Explorer Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX
controls and Active Scripting in the Internet zone and in the Local
intranet zone, you can add sites that you trust to the Internet Explorer
Trusted sites zone. This will allow you to continue to use trusted Web
sites exactly as you do today, while helping to protect you from this
attack on untrusted sites. We recommend that you add only sites that you
trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then
click the Security tab.
2. In the Select a Web content zone to specify its current security
settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel,
click to clear the Require server verification (https:) for all sites in
this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that
you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet
Explorer.

Note Add any sites that you trust not to take malicious action on your
computer. Two in particular that you may want to add are
"*.windowsupdate.microsoft.com" and *.update.microsoft.com (without the
quotation marks). These are the sites that will host the update, and it
requires an ActiveX Control to install the update.

* Set Internet and Local intranet security zone settings to High to
prompt before running ActiveX Controls and Active Scripting in these zones

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

To raise the browsing security level in Microsoft Internet Explorer,
follow these steps:

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 security setting set to High.

Impact of Workaround: There are side effects to prompting before running
ActiveX Controls and Active Scripting. Many Web sites that are on the
Internet or on an intranet use ActiveX or Active Scripting 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 or
Active Scripting 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 or Active Scripting. If you do
not want to be prompted for all these sites, use the steps outlined in
"Add sites that you trust to the Internet Explorer Trusted sites zone .

Add sites that you trust to the Internet Explorer Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX
controls and Active Scripting in the Internet zone and in the Local
intranet zone, you can add sites that you trust to the Internet Explorer
Trusted sites zone. This will allow you to continue to use trusted Web
sites exactly as you do today, while helping to protect you from this
attack on untrusted sites. We recommend that you add only sites that you
trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then
click the Security tab.
2. In the Select a Web content zone to specify its current security
settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel,
click to clear the Require server verification (https:) for all sites in
this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that
you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet
Explorer.

Note Add any sites that you trust not to take malicious action on your
computer. Two in particular that you may want to add are
"*.windowsupdate.microsoft.com" and *.update.microsoft.com (without the
quotation marks). These are the sites that will host the update, and it
requires an ActiveX Control to install the update.

FAQ for Address Bar Spoofing Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2384>
CVE-2006-2384:
What is the scope of the vulnerability?
This is a spoofing vulnerability in Internet Explorer. The vulnerability
could allow an attacker to display spoofed content in a browser window
that displays a modal dialog box. The address bar and other parts of the
trust UI can be displayed from trusted Web sites but the content of the
window contains the attacker s Web page.

What causes the vulnerability?
The address bar and other parts of the trust UI can be persisted from a
trusted Web site that displays a modal browser Window whereas the content
of the browser window is navigated to the attacker s Web site.

How could an attacker exploit the vulnerability?
An attacker could use this vulnerability to create a Web page that would
display a URL of the attacker's choosing in the Address bar, while
displaying a different Web site in the browser window. An attacker could
use this vulnerability to create a specially crafted page that persists
the address bar and other parts of the trust UI from a legitimate site. A
user could then input data into what is thought to be a trusted site when
in fact the data is sent to the attacker s site.

What systems are primarily at risk from the vulnerability?
This vulnerability requires a user to be logged on and visiting 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.

What does the update do?
The update removes the vulnerability by ensuring that the technique used
to persist the address bar and trust UI after navigation occurs is no
longer possible.

When this security bulletin was issued, had this vulnerability been
publicly disclosed?
No. Microsoft received information about this vulnerability through
responsible disclosure.

When this security bulletin was issued, had Microsoft received any reports
that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this
vulnerability had been publicly used to attack customers and had not seen
any examples of proof of concept code published when this security
bulletin was originally issued.

MHT Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2385>
CVE-2006-2385:
A remote code execution vulnerability exists in the way Internet Explorer
saves multipart HTML (.mht) files. An attacker could exploit the
vulnerability by constructing a specially crafted Web page and convince a
user to save this Web page as a multipart HTML file that could potentially
allow remote code execution. An attacker who successfully exploited this
vulnerability could take complete control of an affected system however
significant user interaction is required.

Mitigating Factors for MHT Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2385>
CVE-2006-2385:
* 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 a specially crafted
Web site. Instead, an attacker would have to persuade them to visit the
Web site, typically by getting them to click a link that takes them to the
attacker's Web site and then save the Web page as a multipart HTML file.
In addition, the vulnerability exhibits itself only during the Save As
if a user chooses to save the specially crafted Web page as a Web
Archive, single file (*.mht).

* An already created multipart HTML file cannot be used to trigger this
vulnerability. The vulnerability exhibits itself only during the Save As
if a user chooses to save the specially crafted Web page as a Web
Archive, single file (*.mht).

* Saving the Web page as any other file type does not trigger the
vulnerable code.

* Viewing the Web page in Internet Explorer does not trigger the
vulnerable code.

* 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.

Workarounds for MHT Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2385>
CVE-2006-2385:
Microsoft has tested the following workarounds. While these workarounds
will not correct the underlying vulnerability, they help block known
attack vectors. When a workaround reduces functionality, it is identified
in the following section.

Do not use the "Save As" command in Internet Explorer to save untrusted
Web pages as Web Archive, single file (*.mht).

FAQ for MHT Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2385>
CVE-2006-2385:
What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who
successfully exploited this vulnerability could remotely 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. However, significant user interaction is required.

What causes the vulnerability?
A specially crafted Web page can, when saved as a multipart HTML file
cause memory corruption.

What might an attacker use the vulnerability to do?
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.

How could an attacker exploit the vulnerability?
An attacker could host a specially crafted Web page that is designed to
exploit this vulnerability through Internet Explorer and then persuade a
user to save the Web page as a multipart HTML (.mht) file. This can also
include Web sites that accept or host user-provided content such as banner
advertisements, in addition to compromised Web sites. These Web sites
could contain specially crafted content that could exploit this
vulnerability.

However, to exploit this vulnerability, an attacker would have to persuade
users to visit a Web site and then convince the user to save the Web page
as a multipart HTML file, 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.

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.

What does the update do?
The update removes the vulnerability by modifying the way that Internet
Explorer saves multipart HTML files so that this memory corruption does
not occur.

When this security bulletin was issued, had this vulnerability been
publicly disclosed?
No. Microsoft received information about this vulnerability through
responsible disclosure.

When this security bulletin was issued, had Microsoft received any reports
that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this
vulnerability had been publicly used to attack customers and had not seen
any examples of proof of concept code published when this security
bulletin was originally issued.

Address Bar Spoofing Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-1626>
CVE-2006-1626:
A spoofing vulnerability exists in Internet Explorer that could allow an
attacker to display spoofed content in a browser window. The address bar
and other parts of the trust UI can be displayed from trusted Web sites
but the content of the window contains the attacker s Web page.

Mitigating Factors for Address Bar Spoofing Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-1626>
CVE-2006-1626:
* 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 a specially crafted
Web site. Instead, an attacker would have to persuade them to visit the
Web site, typically by getting them to click a link that takes them to the
attacker's Web site.

* The Restricted sites zone helps reduce attacks that could try to
exploit this vulnerability by preventing Active Scripting from being used
when reading HTML e-mail messages. However, if a user clicks a link in an
e-mail message, they could still be vulnerable to this issue through the
Web-based attack scenario.

By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML
e-mail messages in the Restricted sites zone. Additionally Outlook 2000
opens HTML e-mail messages in the Restricted sites zone if the
<http://go.microsoft.com/fwlink/?LinkId=33334> Outlook E-mail Security
Update has been installed. Outlook Express 5.5 Service Pack 2 opens HTML
e-mail messages in the Restricted sites zone if
<http://go.microsoft.com/fwlink/?LinkId=19527> Microsoft Security Bulletin
MS04-018 has been installed.

* 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. See the FAQ section or this security update for more information about Internet Explorer Enhanced Security Configuration.

Workarounds for Address Bar Spoofing Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-1626>
CVE-2006-1626:
Microsoft has tested the following workarounds. While these workarounds
will not correct the underlying vulnerability, they help block known
attack vectors. When a workaround reduces functionality, it is identified
in the following section.

Configure Internet Explorer to prompt before running Active Scripting or
disable Active Scripting in the Internet and Local intranet security zone

You can help protect against this vulnerability by changing your settings
to prompt before running Active Scripting or to disable Active Scripting
in the Internet and Local intranet security zone. To do this, follow 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 Scripting section, under Active Scripting,
click Prompt or Disable, and then click OK.
5. Click Local intranet, and then click Custom Level.
6. Under Settings, in the Scripting section, under Active Scripting,
click Prompt or Disable, and then click OK.
7. Click OK two times to return to Internet Explorer.

Note Disabling Active Scripting in the Internet and Local intranet
security zones 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.

Impact of Workaround: There are side effects to prompting before running
Active Scripting. Many Web sites that are on the Internet or on an
intranet use Active Scripting to provide additional functionality. For
example, an online e-commerce site or banking site may use Active
Scripting to provide menus, ordering forms, or even account statements.
Prompting before running Active Scripting 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 Active Scripting. If you do not
want to be prompted for all these sites, use the steps outlined in "Add
sites that you trust to the Internet Explorer Trusted sites zone .

Add sites that you trust to the Internet Explorer Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX
controls and Active Scripting in the Internet zone and in the Local
intranet zone, you can add sites that you trust to the Internet Explorer
Trusted sites zone. This will allow you to continue to use trusted Web
sites exactly as you do today, while helping to protect you from this
attack on untrusted sites. We recommend that you add only sites that you
trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then
click the Security tab.
2. In the Select a Web content zone to specify its current security
settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel,
click to clear the Require server verification (https:) for all sites in
this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that
you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet
Explorer.

Note Add any sites that you trust not to take malicious action on your
computer. Two in particular that you may want to add are
"*.windowsupdate.microsoft.com" and *.update.microsoft.com (without the
quotation marks). These are the sites that will host the update, and it
requires an ActiveX Control to install the update.

* Set Internet and Local intranet security zone settings to High to
prompt before running ActiveX Controls and Active Scripting in these zones

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

To raise the browsing security level in Microsoft Internet Explorer,
follow these steps:

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 security setting set to High.

Impact of Workaround: There are side effects to prompting before running
ActiveX Controls and Active Scripting. Many Web sites that are on the
Internet or on an intranet use ActiveX or Active Scripting 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 or
Active Scripting 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 or Active Scripting. If you do
not want to be prompted for all these sites, use the steps outlined in
"Add sites that you trust to the Internet Explorer Trusted sites zone .

Add sites that you trust to the Internet Explorer Trusted sites zone.

After you set Internet Explorer to require a prompt before it runs ActiveX
controls and Active Scripting in the Internet zone and in the Local
intranet zone, you can add sites that you trust to the Internet Explorer
Trusted sites zone. This will allow you to continue to use trusted Web
sites exactly as you do today, while helping to protect you from this
attack on untrusted sites. We recommend that you add only sites that you
trust to the Trusted sites zone.

To do this, follow these steps:

1. In Internet Explorer, click Tools, click Internet Options, and then
click the Security tab.
2. In the Select a Web content zone to specify its current security
settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel,
click to clear the Require server verification (https:) for all sites in
this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that
you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet
Explorer.

Note Add any sites that you trust not to take malicious action on your
computer. Two in particular that you may want to add are
"*.windowsupdate.microsoft.com" and *.update.microsoft.com (without the
quotation marks). These are the sites that will host the update, and it
requires an ActiveX Control to install the update.

FAQ for Address Bar Spoofing Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-1626>
CVE-2006-1626:
What is the scope of the vulnerability?
This is a spoofing vulnerability in Internet Explorer. The vulnerability
could allow an attacker to display spoofed content in a browser window.

What causes the vulnerability?
A spoofing vulnerability exists in Internet Explorer that could allow an
attacker to display spoofed content in a browser window. The address bar
and other parts of the trust UI can be persisted from a trusted Web site
whereas the content of the browser window is navigated to the attacker s
Web site.

How could an attacker exploit the vulnerability?
An attacker could use this vulnerability to create a Web page that would
display a URL of the attacker's choosing in the Address bar, while
displaying a different Web site in the browser window. An attacker could
use this vulnerability to create a specially crafted page that persists
the address bar and other parts of the trust UI from a legitimate site.

What systems are primarily at risk from the vulnerability?
This vulnerability requires a user to be logged on and visiting 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.

What does the update do?
The update removes the vulnerability by ensuring that the technique used
to persist the address bar and trust UI after navigation occurs is no
longer possible.

When this security bulletin was issued, had Microsoft received any reports
that this vulnerability was being exploited?
No. Microsoft had seen examples of proof of concept code published
publicly but had not received any information to indicate that this
vulnerability had been publicly used to attack customers when this
security bulletin was originally issued.

Does applying this security update help protect customers from the code
that has been published publicly that attempts to exploit this
vulnerability?
Yes. This security update addresses the vulnerability that potentially
could be exploited by using the published proof of concept code. The
vulnerability that has been addressed has been assigned the Common
Vulnerability and Exposure number CVE-2006-1626.


ADDITIONAL INFORMATION

The information has been provided by Microsoft Security.
The original article can be found at:
<http://www.microsoft.com/technet/security/Bulletin/MS06-021.mspx>
http://www.microsoft.com/technet/security/Bulletin/MS06-021.mspx



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