[NT] Internet Explorer Bundled Flash Player Code Execution (MS06-020)

SecuriTeam <[email protected]> 10 May 2006 12:33:27 +0200

Newsgroups	gmane.comp.security.securiteam
Message-ID	<[email protected]>

The following security advisory is sent to the securiteam mailing list, and can be found at the SecuriTeam web site: http://www.securiteam.com
- - promotion

The SecuriTeam alerts list - Free, Accurate, Independent.

Get your security news from a reliable source.
http://www.securiteam.com/mailinglist.html

- - - - - - - - -

Internet Explorer Bundled Flash Player Code Execution (MS06-020)
------------------------------------------------------------------------

SUMMARY

Improper user input validation allows attackers to execute arbitrary code
and gain user privileges by using Macromedia Flash that arrives with
Microsoft Internet Explorer 6 by default.

DETAILS

Vulnerable Systems:
* Microsoft Windows XP Service Pack 1 and Microsoft Windows XP Service
Pack 2
<http://www.microsoft.com/downloads/details.aspx?FamilyId=B2B8F9A8-4874-405A-9F0C-768B2631673A> Download the update
* 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.

Immune Systems:
* Microsoft Windows 2000 Service Pack 4
* 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
* Windows XP Professional x64 Edition

Flash Player Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-0024>
CVE-2006-0024:
A remote code execution vulnerability exists in Macromedia Flash Player
from Adobe because of the way that it handles Flash Animation (SWF) files.
An attacker could exploit the vulnerability by constructing a specially
crafted Flash Animation (SWF) file that could potentially allow remote
code execution if a user visited a Web site containing the specially
crafted SWF file or viewed an e-mail message containing the specially
crafted SWF file as an attachment. An attacker who successfully exploited
this vulnerability could take complete control of an affected system.

Mitigating Factors for Flash Player Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-0024>
CVE-2006-0024:
* Customers that have followed the guidance in
<http://go.microsoft.com/fwlink/?LinkId=62431> Adobe Security Bulletin
APSB06-03 are not at risk from the vulnerability.

* By default, Microsoft Windows 2000 Service Pack 4, Microsoft Windows
Server 2003 and Microsoft Windows Server 2003 Service Pack 1 do not ship
with a vulnerable version of Flash Player installed. However, customers
that have installed a version of Flash Player 7.0.62.0 or 8.0.22.0 or
earlier on these versions of Windows are encouraged to follow the guidance
in the <http://go.microsoft.com/fwlink/?LinkId=62431> Adobe Security
Bulletin APSB06-03.

* 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 malicious 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
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 and ActiveX
controls from being used when reading HTML e-mail. However, if a user
clicks on a link within an e-mail they could still be vulnerable to this
issue through the Web-based attack scenario described previously.

* 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 Outlook
<http://go.microsoft.com/fwlink/?LinkId=33334> 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 Microsoft Security Bulletin
<http://go.microsoft.com/fwlink/?LinkId=19527> MS04-018 has been
installed.

Workarounds for Flash Player Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-0024>
CVE-2006-0024:
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.

* Temporarily prevent the Flash Player ActiveX control from running in
Internet Explorer for Windows XP Service Pack 2

You can help protect against this vulnerability by temporarily preventing
the Flash Player ActiveX control from running in Internet Explorer. On
Windows XP Service Pack 2 use the Internet Explorer Manage Add-ons feature
to disable the ActiveX control.

1. Start Internet Explorer.
2. On the Tools menu, click Manage Add-ons.
3. Locate and click on Shockwave Flash Object .
4. To disable the add-on, click Disable, and then click OK.

Note If you cannot locate the ActiveX control then use the drop-down box
to switch from Add-ons currently being used in Internet Explorer to
Add-ons that have been used by Internet Explorer and follow steps 3 and
4. If the ActiveX control is not present in this list you either have not
used the ActiveX control before or it is not present on your system. See
the workaround Temporarily prevent the Flash Player ActiveX control from
running in Internet Explorer for additional information.

For more information on the Internet Explorer Manage Add-ons feature in
Windows XP Service Pack 2, see Microsoft Knowledge Base Article 883256.

Impact of Workaround: Applications and Web sites that require the Flash
Player ActiveX control may no longer function correctly. If you implement
this workaround it would affect any Flash Player ActiveX control you have
installed on your system.

To regain functionality you need to use the Internet Explorer Manage
Add-ons feature to enable the ActiveX control.

* Temporarily prevent the Flash Player ActiveX control from running in
Internet Explorer

Temporarily prevent attempts to instantiate the Flash Player ActiveX
control in Internet Explorer by setting the kill bit for the control.

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.

We recommend that you back up the registry before you edit it.

Use the following text to create a .reg file that temporarily prevents
attempts to instantiate the Flash Player ActiveX control in Internet
Explorer. You can copy the following text, paste it into a text editor
such as Notepad, and then save the file with the .reg file name extension.
Run the .reg file on the vulnerable client.

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX
Compatibility\{1171A62F-05D2-11D1-83FC-00A0C9089C5A}]
"Compatibility Flags"=dword:00000400

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX
Compatibility\{D27CDB6E-AE6D-11cf-96B8-444553540000}]
"Compatibility Flags"=dword:00000400

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX
Compatibility\{D27CDB70-AE6D-11cf-96B8-444553540000}]
"Compatibility Flags"=dword:00000400

Close Internet Explorer, and reopen it for the changes to take effect.

For detailed steps about stopping a control from running in Internet
Explorer, see <http://support.microsoft.com/kb/240797> Microsoft
Knowledge Base Article 240797. Follow these steps and create a
Compatibility Flags value in the registry to prevent the Flash Player
ActiveX control from running in Internet Explorer.

To regain functionality you need to undo the kill bits for the Flash
Player ActiveX control remove the registry keys added to temporarily
prevent attempts to instantiate the Flash Player ActiveX control in
Internet Explorer.

Modify the Access Control List on the Flash Player ActiveX control to
temporarily prevent it from running in Internet Explorer

To modify the Access Control List (ACL) on the Flash Player ActiveX
control to be more restrictive, follow these steps:

1. Click Start, click Run, type "cmd" (without the quotation marks), and
then click OK.
2. Type the following commands at a command prompt. Make a note of the
current files ACL s, including inheritance settings. You may need this
list if you have to undo these modifications:

cacls %windir%\system32\Macromed\Flash\flash.ocx
cacls %windir%\system32\Macromed\Flash\swflash.ocx

3. Type the following command at a command prompt to deny the everyone
group access to this file:

echo y|cacls %windir%\system32\Macromed\Flash\flash.ocx /d everyone
echo y|cacls %windir%\system32\Macromed\Flash\swflash.ocx /d everyone

4. Close Internet Explorer, and reopen it for the changes to take effect.

To regain functionality you need to undo the modifications to the Access
Control List on the ActiveX control you have on your system.

Un-register the Flash Player ActiveX Control

To un-register the Flash Player ActiveX control, follow these steps:

1. Click Start, click Run, type "regsvr32.exe /u
%windir%\system32\Macromed\Flash\flash.ocx" (without the quotation marks),
and then click OK.
2. A dialog box confirms that the un-registration process has succeeded.
Click OK to close the dialog box.
3. Click Start, click Run, type "regsvr32.exe /u
%windir%\system32\Macromed\Flash\swflash.ocx" (without the quotation
marks), and then click OK.
4. A dialog box confirms that the unregistration process has succeeded.
Click OK to close the dialog box.
5. Close Internet Explorer, and reopen it for the changes to take effect.

To reregister the Flash Player ActiveX control, follow these steps:

1. Click Start, click Run, type "regsvr32.exe
%windir%\system32\Macromed\Flash\flash.ocx" (without the quotation marks),
and then click OK.
2. A dialog box confirms that the registration process has succeeded.
Click OK to close the dialog box.
3. Click Start, click Run, type "regsvr32.exe
%windir%\system32\Macromed\Flash\swflash.ocx" (without the quotation
marks), and then click OK.
4. A dialog box confirms that the registration process has succeeded.
Click OK to close the dialog box.
5. Close Internet Explorer, and reopen it for the changes to take effect.

* Restrict access to the Macromedia Flash folder by using a Software
Restriction Policy

To restrict access to the Macromedia Flash folder
(%windir%\system32\Macromed\Flash\) on Windows XP and later versions you
can create a
<http://www.microsoft.com/technet/prodtechnol/winxppro/maintain/rstrplcy.mspx> Software Restriction Policy. To create this policy, use a registry script or create a Group Policy setting to block the loading of the Flash Player ActiveX control.

For more information about Group Policy, visit the following Microsoft Web
sites:
*
<http://www.microsoft.com/technet/prodtechnol/windowsserver2003/technologies/directory/activedirectory/stepbystep/gpfeat.mspx> Step-by-Step Guide to Understanding the Group Policy Feature Set
*
<http://www.microsoft.com/technet/prodtechnol/windows2000serv/howto/grpolwt.mspx> Windows 2000 Group Policy
*
<http://www.microsoft.com/technet/prodtechnol/windowsserver2003/technologies/featured/gp/default.mspx> Group Policy in Windows Server 2003

Note Using Registry Editor incorrectly can cause serious problems that may
require you to reinstall your operating system. Microsoft cannot guarantee
that problems resulting from the incorrect use of Registry Editor can be
solved. Use Registry Editor at your own risk. For information about how to
edit the registry, view the "Change Keys and Values" Help topic in
Registry Editor (Regedit.exe) or view the "Add and Delete Information in
the Registry" and "Edit Registry Data" Help topics in Regedt32.exe.

We recommend that you back up the registry before you edit it.

Use the following text to create a .reg file to restrict access to the
Macromedia Flash folder. You can copy the following text, paste it into a
text editor such as Notepad, and then save the file with the .reg file
name extension. Run the .reg file on the vulnerable client.

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Safer\CodeIdentifiers]
"TransparentEnabled"=dword:00000002

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Safer\CodeIdentifiers\0\Paths\{2742f840-c2d8-4eb3-a486-0a9d0879f29f}]
"LastModified"=hex(b):10,c3,8a,19,c6,e3,c5,01
"Description"="Block Macromedia Flash"
"SaferFlags"=dword:00000000
"ItemData"=hex(2):25,00,77,00,69,00,6e,00,64,00,69,00,72,00,25,00,5c,00,73,00,\
79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,6d,00,61,00,63,00,72,00,6f,\
00,6d,00,65,00,64,00,5c,00,66,00,6c,00,61,00,73,00,68,00,5c,00,2a,00,00,00

Change your Internet Explorer settings to prompt before running ActiveX
controls or disable ActiveX controls in the Internet security zone and in
the 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 following method:

Restrict Web sites to only your trusted Web sites.

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 Internet Explorer's
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.

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). This is the site 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 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.

* Remove the Flash Player from your system

If you want to remove Flash Player, refer to the
<http://www.macromedia.com/go/tn_15511> Adobe Flash Player Support FAQ for
instructions.

To regain functionality you need install the Flash Player ActiveX control
from the <http://www.macromedia.com/> Adobe Web site

FAQ for Flash Player Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-0024>
CVE-2006-0024.
What is the scope of the vulnerability?
This is a remote code execution vulnerability. If a user is logged on with
administrative user rights, an attacker who successfully exploited this
vulnerability could take complete control of an affected system. An
attacker could then install programs; view, change, or delete data; or
create new accounts with full user rights. Users whose accounts are
configured to have fewer user rights on the system could be less impacted
than users who operate with administrative user rights.

What causes the vulnerability?
An unchecked buffer in Flash Player.

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

How could an attacker exploit the vulnerability?
An attacker could host a Web site containing the specially crafted SWF
file that is designed to exploit this vulnerability through Internet
Explorer and then persuade a user to view the Web site.

What systems are primarily at risk from the vulnerability?
Workstations and terminal servers are primarily at risk. Servers could be
at more risk if users who do not have sufficient administrative
permissions are given the ability to log on to servers and to run
programs. However, best practices strongly discourage allowing this.

Are Windows 98, Windows 98 Second Edition or Windows Millennium Edition
critically affected by this vulnerability?
Yes. Windows 98, Windows 98 Second Edition, and Windows Millennium Edition
users are critically affected by this vulnerability. The security updates
for Flash Player 6 are available for download only from the
<http://go.microsoft.com/fwlink/?LinkId=21130> Windows Update Web site.
Visit the Adobe website for
<http://go.microsoft.com/fwlink/?LinkId=62431> updates to Flash Player 7
and higher. For more information about severity ratings, visit the
following <http://go.microsoft.com/fwlink/?LinkId=21140> Web site.

What does the update do?
The update removes the vulnerabilities by modifying the way that the Flash
Player handles Flash Animation (SWF) files.

When this security bulletin was issued, had this vulnerability been
publicly disclosed?
No. Microsoft had not received any information to indicate that this
vulnerability had been publicly disclosed when this security bulletin was
originally issued. This vulnerability is also discussed in
<http://go.microsoft.com/fwlink/?LinkId=62431> Adobe Security Bulletin
APSB06-03.

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.

Flash Player Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2005-2628>
CVE-2005-2628:
A remote code execution vulnerability exists in Macromedia Flash Player
from Adobe because of the way that it handles Flash Animation (SWF) files.
An attacker could exploit the vulnerability by constructing a malicious
Flash Animation (SWF) file that could potentially allow remote code
execution if a user visited a Web site containing the specially crafted
SWF file or viewed an e-mail message containing the specially crafted SWF
file as an attachment. An attacker who successfully exploited this
vulnerability could take complete control of an affected system.

Mitigating Factors for Flash Player Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2005-2628>
CVE-2005-2628:
* Customers that have followed the guidance in
<http://go.microsoft.com/fwlink/?LinkId=56128> Macromedia Security
Bulletin MPSB05-07 are not at risk from the vulnerability.

* By default, Microsoft Windows 2000 Service Pack 4, Microsoft Windows
Server 2003 and Microsoft Windows Server 2003 Service Pack 1 do not ship
with a vulnerable version of the Flash Player installed. However,
customers that have installed a version of Flash Player 7.0.61.0 or
8.0.22.0 or earlier on these versions of Windows are encouraged to follow
the guidance in the <http://go.microsoft.com/fwlink/?LinkId=62431> Adobe
Security Bulletin APSB06-03.

* 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.

Workarounds for Flash Player Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2005-2628>
CVE-2005-2628
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.

* Temporarily prevent the Flash Player ActiveX control from running in
Internet Explorer for Windows XP Service Pack 2

You can help protect against this vulnerability by temporarily preventing
the Flash Player ActiveX control from running in Internet Explorer. On
Windows XP Service Pack 2 and Windows Server 2003 Service Pack 1 use the
Internet Explorer Manage Add-ons feature to disable the ActiveX control.