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             AUSCERT External Security Bulletin Redistribution

                               ESB-2011.1020
         Vulnerability in .NET Framework and Microsoft Silverlight
                Could Allow Remote Code Execution (2604930)
                              12 October 2011

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

Product:           Microsoft .NET Framework
                   Microsoft Silverlight
Publisher:         Microsoft
Operating System:  Windows XP
                   Windows Server 2003
                   Windows Vista
                   Windows 7
                   Windows Server 2008
                   Mac OS X
Impact/Access:     Execute Arbitrary Code/Commands -- Remote with User Interaction
Resolution:        Patch/Upgrade
CVE Names:         CVE-2011-1253  

Original Bulletin: 
   http://technet.microsoft.com/en-us/security/bulletin/ms11-078

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Microsoft Security Bulletin MS11-078 - Critical
Vulnerability in .NET Framework and Microsoft Silverlight Could Allow Remote 
Code Execution (2604930)

Published: Tuesday, October 11, 2011

Version: 1.0

General Information

Executive Summary

This security update resolves a privately reported vulnerability in Microsoft 
.NET Framework and Microsoft Silverlight. The vulnerability could allow remote 
code execution on a client system if a user views a specially crafted Web page 
using a Web browser that can run XAML Browser Applications (XBAPs) or 
Silverlight applications. 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 vulnerability could also allow remote code 
execution on a server system running IIS, if that server allows processing 
ASP.NET pages and an attacker succeeds in uploading a specially crafted ASP.NET 
page to that server and then executes the page, as could be the case in a Web 
hosting scenario. This vulnerability could also be used by Windows .NET 
applications to bypass Code Access Security (CAS) restrictions.

This security update is rated Critical for Microsoft .NET Framework 1.0 Service 
Pack 3, Microsoft .NET Framework 1.1 Service Pack 1, Microsoft .NET Framework 
2.0 Service Pack 2, Microsoft .NET Framework 3.5.1, and Microsoft .NET 
Framework 4 on all supported editions of Microsoft Windows; and Microsoft 
Silverlight 4. 

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 2
Windows Vista x64 Edition Service Pack 2
Windows Server 2008 for 32-bit Systems Service Pack 2
Windows Server 2008 for x64-based Systems Service Pack 2
Windows Server 2008 for Itanium-based Systems Service Pack 2
Windows 7 for 32-bit Systems
Windows 7 for 32-bit Systems Service Pack 1
Windows 7 for x64-based Systems
Windows 7 for x64-based Systems Service Pack 1
Windows Server 2008 R2 for x64-based Systems
Windows Server 2008 R2 for x64-based Systems Service Pack 1
Windows Server 2008 R2 for Itanium-based Systems
Windows Server 2008 R2 for Itanium-based Systems Service Pack 1
Microsoft .NET Framework 1.0 Service Pack 3 (Media Center Edition 2005 and 
  Tablet PC Edition 2005 only)
Microsoft .NET Framework 1.1 Service Pack 1
Microsoft .NET Framework 2.0 Service Pack 2
Microsoft .NET Framework 4 [1]
Microsoft .NET Framework 3.5.1
Microsoft Silverlight 4 when installed on Mac
Microsoft Silverlight 4 when installed on all supported releases of Microsoft 
  Windows clients

[1] .NET Framework 4 and .NET Framework 4 Client Profile affected. The .NET 
Framework version 4 redistributable packages are available in two profiles: .NET 
Framework 4 and .NET Framework 4 Client Profile. .NET Framework 4 Client Profile 
is a subset of .NET Framework 4. The vulnerability addressed in this update 
affects both .NET Framework 4 and .NET Framework 4 Client Profile. For more 
information, see the MSDN article, Installing the .NET Framework.

Vulnerability Information

.NET Framework Class Inheritance Vulnerability - CVE-2011-1253

A remote code execution vulnerability exists in the way that the Microsoft .NET 
Framework and Silverlight framework restrict inheritance within classes. 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.

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