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             AUSCERT External Security Bulletin Redistribution

                               ESB-2010.0411
 Vulnerability in Microsoft SharePoint Could Allow Elevation of Privilege
                               30 April 2010

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

Product:           Microsoft Office SharePoint Server 2007
                   Microsoft Windows SharePoint Services 3.0
Publisher:         Microsoft
Operating System:  Windows
Impact/Access:     Increased Privileges -- Existing Account
Resolution:        Mitigation

Original Bulletin: 
   http://www.microsoft.com/technet/security/advisory/983438.mspx

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Microsoft Security Advisory (983438)
Vulnerability in Microsoft SharePoint Could Allow Elevation of Privilege

Published: April 29, 2010

Version: 1.0

General Information

Executive Summary

  Microsoft is investigating new public reports of a possible vulnerability in 
  Microsoft Windows SharePoint Services 3.0 and Microsoft Office SharePoint 
  Server 2007. The vulnerability could allow an attacker to run arbitrary script
  that could result in elevation of privilege within the SharePoint site, as 
  opposed to elevation of privilege within the workstation or server 
  environment.

  We are actively working with partners in our Microsoft Active Protections 
  Program (MAPP) to provide information that they can use to provide broader 
  protections to customers.

  Upon completion of this investigation, Microsoft will take the appropriate 
  action to help protect our customers. This may include providing a security 
  update through our monthly release process or providing an out-of-cycle 
  security update, depending on customer needs.

Affected Software

  Microsoft Office SharePoint Server 2007 Service Pack 1 and Microsoft Office 
    SharePoint Server 2007 Service Pack 2 (32-bit editions)
  Microsoft Office SharePoint Server 2007 Service Pack 1 and Microsoft Office 
    SharePoint Server 2007 Service Pack 2 (64-bit editions)
  Microsoft Windows SharePoint Services 3.0 Service Pack 1 and Microsoft Windows
    SharePoint Services 3.0 Service Pack 2 (32-bit editions)
  Microsoft Windows SharePoint Services 3.0 Service Pack 1 and Microsoft Windows
    SharePoint Services 3.0 Service Pack 2 (64-bit editions)

Mitigating Factors

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

  An attacker can cause arbitrary JavaScript to be run by the user clicking the
  specially crafted URL, but the attacker would not be able to steal the 
  logged-on user's authentication credentials due to the way SharePoint Server 
  handles the HttpOnly authentication cookie

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

  Internet Explorer 8 users browsing to a SharePoint site in the Internet Zone 
  are at a reduced risk because, by default, the XSS Filter in Internet Explorer
  8 prevents this attack in the Internet Zone. The Internet Explorer 8 XSS 
  Filter, however, is not enabled by default in the Intranet Zone.

Suggested Actions

  Customers can mitigate the impact to systems running Microsoft Windows 
  SharePoint Services 3.0 or Microsoft Office SharePoint Server 2007 by applying
  the following workarounds.

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

  Restrict Access to SharePoint Help.aspx

  An administrator can apply an access control list to SharePoint Help.aspx to 
  ensure that they can no longer be loaded. This effectively prevents 
  exploitation of the vulnerability using this attack vector.

  To restrict access to the vulnerable Help.aspx:

    Run the following commands from a command prompt:

    cacls "%ProgramFiles%\Common Files\Microsoft Shared\Web Server Extensions\12\TEMPLATE\LAYOUTS\Help.aspx" /E /P everyone:N

    cacls "%ProgramFiles(x86)%\Common Files\Microsoft Shared\Web Server Extensions\12\TEMPLATE\LAYOUTS\Help.aspx" /E /P everyone:N

  Impact of workaround. This workaround will disable all help functionality from
  the SharePoint server.

  How to undo the workaround.

  Run the following commands from a command prompt:

    takeown /f "%ProgramFiles%\Common Files\Microsoft Shared\Web Server Extensions\12\TEMPLATE\LAYOUTS\Help.aspx"

    takeown /f "%ProgramFiles(x86)%\Common Files\Microsoft Shared\Web Server Extensions\12\TEMPLATE\LAYOUTS\Help.aspx"

    cacls "%ProgramFiles%\Common Files\Microsoft Shared\Web Server Extensions\12\TEMPLATE\LAYOUTS\Help.aspx" /E /R everyone

    cacls "%ProgramFiles(x86)%\Common Files\Microsoft Shared\Web Server Extensions\12\TEMPLATE\LAYOUTS\Help.aspx" /E /R everyone

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