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             AUSCERT External Security Bulletin Redistribution

    Vulnerability in .NET Framework Could Allow Information Disclosure
                              10 August 2011


        AusCERT Security Bulletin Summary

Product:           Microsoft .NET Framework 2.0 Service Pack 2
                   Microsoft .NET Framework 3.5.1
                   Microsoft .NET Framework 4
Publisher:         Microsoft
Operating System:  Windows
Impact/Access:     Access Confidential Data -- Remote with User Interaction
                   Denial of Service        -- Remote with User Interaction
Resolution:        Patch/Upgrade
CVE Names:         CVE-2011-1978  

Original Bulletin: 

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Microsoft Security Bulletin MS11-069 - Moderate
Vulnerability in .NET Framework Could Allow Information Disclosure (2567951)
Published: August 09, 2011
Version: 1.0

General Information

Executive Summary

   This security update resolves a privately reported vulnerability in
   Microsoft .NET Framework. The vulnerability could allow information
   disclosure if a user views a specially crafted Web page using a Web
   browser that can run XAML Browser Applications (XBAPs). 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 attacker's Web site. This
   vulnerability could also be used by Windows .NET applications to bypass
   Code Access Security (CAS) restrictions.

   This security update is rated Moderate for 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. For more
   information, see the subsection, Affected and Non-Affected Software, in
   this section.

Affected Software

   Microsoft .NET Framework 2.0 Service Pack 2
   Microsoft .NET Framework 3.5.1
   Microsoft .NET Framework 4

Vulnerability Information

   Socket Restriction Bypass Vulnerability - CVE-2011-1978

   An information disclosure vulnerability exists in the way that .NET
   Framework improperly validates the trust level within the
   System.Net.Sockets namespace. An attacker who successfully exploited
   this vulnerability would be able to access information not intended to
   be exposed. Additionally, this vulnerability could be used by an
   attacker to direct network traffic from a victim's system to other
   network resources the victim can access. This could allow an attacker
   to perform a denial of service to any system the victim's system can
   access or use the victim's system to perform scanning of network
   resources available to the victim. Note that this vulnerability would
   not allow an attacker to execute code or to elevate their user rights
   directly, but it could be used to produce information that could be
   used to try to further compromise the affected system.

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