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             AUSCERT External Security Bulletin Redistribution

                               ESB-2011.0006
          Vulnerability in Graphics Rendering Engine Could Allow
                           Remote Code Execution
                              5 January 2011

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           Windows Graphics Rendering Engine
Publisher:         Microsoft
Operating System:  Windows XP
                   Windows Vista
                   Windows Server 2003
                   Windows Server 2008
Impact/Access:     Execute Arbitrary Code/Commands -- Remote with User Interaction
Resolution:        Mitigation
CVE Names:         CVE-2010-3970  

Original Bulletin: 
   http://www.microsoft.com/technet/security/advisory/2490606.mspx

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Microsoft Security Advisory (2490606)

Vulnerability in Graphics Rendering Engine Could Allow Remote Code Execution

Published: January 04, 2011

Version: 1.0

Executive Summary

Microsoft is investigating new public reports of a vulnerability in the 
Windows Graphics Rendering Engine. An attacker who successfully exploited this
vulnerability could run arbitrary code in the security context of the 
logged-on user. 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.

We are not aware of attacks that try to use the reported vulnerability or of 
customer impact at this time.

CVE Reference CVE-2010-3970


Affected Software

  Windows XP Service Pack 3
  Windows XP Professional x64 Edition Service Pack 2
  Windows Server 2003 Service Pack 2
  Windows Server 2003 x64 Edition Service Pack 2
  Windows Server 2003 with SP2 for Itanium-based Systems
  Windows Vista Service Pack 1
  Windows Vista Service Pack 2
  Windows Vista x64 Edition Service Pack 1
  Windows Vista x64 Edition Service Pack 2
  Windows Server 2008 for 32-bit Systems 
  Windows Server 2008 for 32-bit Systems Service Pack 2**
  Windows Server 2008 for x64-based Systems 
  Windows Server 2008 for x64-based Systems Service Pack 2**
  Windows Server 2008 for Itanium-based Systems 
  Windows Server 2008 for Itanium-based Systems Service Pack 2


Non-Affected Software

  Windows 7 for 32-bit Systems
  Windows 7 for x64-based Systems
  Windows Server 2008 R2 for x64-based Systems
  Windows Server 2008 R2 for Itanium-based Systems

**Server Core installation not affected.


Mitigating Factors

Mitigation refers to a setting, common configuration, or general 
best-practice, existing in a default state, that could reduce the severity of
exploitation of a vulnerability. The following mitigating factors may be 
helpful in your situation:

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 
convince 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
attackers Web site.

The vulnerability cannot be exploited automatically through e-mail. For an 
attack to be successful, a user must open an attachment that is sent in an 
e-mail message.

An attacker who successfully exploited this vulnerability could gain the same
user rights as the logged-on 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

Workaround refers to a setting or configuration change that does not correct 
the underlying issue but would help block known attack vectors before a 
security update is available. Microsoft has tested the following workarounds 
and states in the discussion whether a workaround reduces functionality:

 Modify the Access Control List (ACL) on shimgvw.dll

To modify the ACL on shimgvw.dll to be more restrictive, run the following 
commands from a command prompt as an administrator:

For 32-bit editions of Windows XP and Windows Server 2003:

  Echo y| cacls %WINDIR%\SYSTEM32\shimgvw.dll /E /P everyone:N

For 64-bit editions of Windows XP and Windows Server 2003:

  Echo y| cacls %WINDIR%\SYSTEM32\shimgvw.dll /E /P everyone:N 
  Echo y| cacls %WINDIR%\SYSWOW64\shimgvw.dll /E /P everyone:N

For 32-bit editions of Windows Vista and Windows Server 2008:

  takeown /f %WINDIR%\SYSTEM32\SHIMGVW.DLL
  icacls %WINDIR%\SYSTEM32\SHIMGVW.DLL /save %TEMP%\SHIMGVW_ACL.TXT
  icacls %WINDIR%\SYSTEM32\SHIMGVW.DLL /deny everyone:(F)

For 64-bit editions of Windows Vista and Windows Server 2008:

  takeown /f %WINDIR%\SYSTEM32\SHIMGVW.DLL
  takeown /f %WINDIR%\SYSWOW64\SHIMGVW.DLL
  icacls %WINDIR%\SYSTEM32\SHIMGVW.DLL /save %TEMP%\SHIMGVW_ACL32.TXT
  icacls %WINDIR%\SYSWOW64\SHIMGVW.DLL /save %TEMP%\SHIMGVW_ACL64.TXT
  icacls %WINDIR%\SYSTEM32\SHIMGVW.DLL /deny everyone:(F)
  icacls %WINDIR%\SYSWOW64\SHIMGVW.DLL /deny everyone:(F)

Impact of Workaround: Media files typically handled by the Graphics
Rendering Engine will not be displayed properly.

How to undo the workaround:

Run the following commands from a command prompt as an administrator:

For 32-bit editions of Windows XP and Windows Server 2003:

  cacls %WINDIR%\SYSTEM32\shimgvw.dll /E /R everyone

For 64-bit editions of Windows XP and Windows Server 2003:

  cacls %WINDIR%\SYSTEM32\shimgvw.dll /E /R everyone 
  cacls %WINDIR%\SYSWOW64\shimgvw.dll /E /R everyone

For 32-bit editions of Windows Vista and Windows Server 2008:

  icacls %WINDIR%\SYSTEM32 /restore %TEMP%\SHIMGVW_ACL.TXT

For 64-bit editions of Windows Vista and Windows Server 2008:

  icacls %WINDIR%\SYSTEM32 /restore %TEMP%\SHIMGVW_ACL32.TXT 
  icacls %WINDIR%\SYSWOW64 /restore %TEMP%\SHIMGVW_ACL64.TXT

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