[NT] Vulnerability in Microsoft Office Allows Code Execution (MS08-013)

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Vulnerability in Microsoft Office Allows Code Execution (MS08-013)
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SUMMARY

This critical security update resolves a privately reported vulnerability
in Microsoft Office. The vulnerability could allow remote code execution
if a user opens a specially crafted Microsoft Office file with a malformed
object inserted into the document. 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.

This is a critical security update for all supported editions of Microsoft
Office 2000 and an important security update for Microsoft Office XP,
Microsoft Office 2003 and Microsoft Office 2004 for Mac. For more
information, see the subsection, Affected and Non-Affected Software, in
this section.

DETAILS

Affected Software
Office Suite and Other Affected Software - Maximum Security Impact -
Aggregate Severity Rating - Bulletins Replaced by this Update
*
<http://www.microsoft.com/downloads/details.aspx?FamilyId=5FB74E24-D9EE-4951-9C46-E1C84617F097> Microsoft Office 2000 Service Pack 3 (KB944425) - Remote Code Execution - Critical - MS06-047
*
<http://www.microsoft.com/downloads/details.aspx?FamilyId=3E147B1A-F3BE-465F-8587-7F3A33D6A6E5> Microsoft Office XP Service Pack 3 (KB944423) - Remote Code Execution - Important - MS06-047
*
<http://www.microsoft.com/downloads/details.aspx?FamilyId=F4AC0F34-4604-4BBE-9669-01DB645041CA> Microsoft Office 2003 Service Pack 2 (KB945185) - Remote Code Execution - Important - MS06-047
*
<http://www.microsoft.com/downloads/details.aspx?FamilyId=36B00C58-192D-488C-A069-730C69F0B6B0> Microsoft Office 2004 for Mac (KB948056) - Remote Code Execution - Important - MS07-060

Non-Affected Software
* Microsoft Office 2003 Service Pack 3
* Microsoft Excel Viewer 2003
* Microsoft PowerPoint 2003 Viewer
* Microsoft Visio 2003 Viewer
* Microsoft Word Viewer 2003
* 2007 Microsoft Office System
* 2007 Microsoft Office System Service Pack 1
* Microsoft Office 2008 for Mac

Microsoft Office Execution Jump Vulnerability - CVE-2008-0103
The vulnerability could allow remote code execution if a user opens a
specially crafted Microsoft Office document with a malformed object
inserted into the document. 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.

CVE Information:
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-0103>
CVE-2008-0103

Mitigating Factors for Microsoft Office Execution Jump Vulnerability -
CVE-2008-0103
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:

* 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.

* 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 persuade 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.

* An attacker who successfully exploited this vulnerability could take
complete control of an affected system. 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.

* Users who have installed and are using the Office Document Open
Confirmation Tool for Office 2000 will be prompted with Open, Save, or
Cancel before opening a document. The features of the Office Document Open
Confirmation Tool are incorporated in Office XP and later editions of
Office.

Workarounds for Microsoft Office Execution Jump Vulnerability -
CVE-2008-0103
Workaround refers to a setting or configuration change that does not
correct the underlying vulnerability 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 VBE6.dll

To restrict access to VBE6.dll, type the following at the command prompt:

For Windows XP:

Echo y|cacls "%ProgramFiles%\common files\microsoft
shared\vba\vba6\vbe6.dll" /E /P everyone:N

For Windows Vista:

Takeown.exe /f "%ProgramFiles%\common files\microsoft
shared\vba\vba6\vbe6.dll"
Icacls.exe "%ProgramFiles%\common files\microsoft
shared\vba\vba6\vbe6.dll" /save %TEMP%\VBE6_ACL.TXT
Icacls.exe "%ProgramFiles%\common files\microsoft
shared\vba\vba6\vbe6.dll" /deny everyone:(F)

Impact of workaround: The impact of implementing this workaround is that
Microsoft Office files with VBA content (such as with macros) will no
longer load.

How to undo the workaround: To rollback this workaround, type the
following at the command prompt:

For Windows XP:

cacls "%ProgramFiles%\common files\microsoft shared\vba\vba6\vbe6.dll" /E
/R everyone

For Windows Vista:

icacls "%ProgramFiles%\common files\microsoft shared\vba\vba6\vbe6.dll"
/grant everyone:(F)
icacls "%ProgramFiles%\common files\microsoft shared\vba\vba6" /restore
%TEMP%\VBE6_ACL.TXT

* Do not open or save Microsoft Office files that you receive from
untrusted sources or that you receive unexpectedly from trusted sources.
This vulnerability could be exploited when a user opens a specially
crafted file.

FAQ for Microsoft Office Execution Jump Vulnerability - CVE-2008-0103
What is the scope of the vulnerability?
This is a remote code execution vulnerability In Microsoft Office. 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?
The vulnerability is caused by a memory handling error in Microsoft Office
when a user opens a specially crafted Office file with malformed objects
inserted. The error may corrupt system memory in such a way that an
attacker could execute arbitrary code.

What might an attacker use the vulnerability to do?
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.

How could an attacker exploit the vulnerability?
This vulnerability requires that a user open a specially crafted Office
file with an affected edition of Microsoft Office.

In an e-mail attack scenario, an attacker could exploit the vulnerability
by sending a specially-crafted Office file to the user and by convincing
the user to open the file.

In a Web-based attack scenario, an attacker would have to host a Web site
that contains a Office file that is used to attempt to exploit this
vulnerability. In addition, compromised Web sites and Web sites that
accept or host user-provided content could contain specially crafted
content that could exploit this vulnerability. An attacker would have no
way to force users to visit a specially crafted Web site. Instead, an
attacker would have to convince them to visit the Web site, typically by
getting them to click a link in an e-mail message or Instant Messenger
message that takes them to the attacker's Web site.

What systems are primarily at risk from the vulnerability?
Systems where Microsoft Office is used are primarily at risk. Servers
could be at more risk if administrators allow users to log on to servers
and to run programs. However, best practices strongly discourage allowing
this.

What does the update do?
The update removes the vulnerability by modifying the way Office manages
memory allocations when opening Office documents with object information
inserted in the documents.

When this security bulletin was issued, had this vulnerability been
publicly disclosed?
No. Microsoft received information about this vulnerability through
responsible disclosure. Microsoft had not received any information to
indicate that this vulnerability had been publicly disclosed when this
security bulletin was originally issued. This security bulletin addresses
the privately disclosed vulnerability as well as additional issues
discovered through internal investigations.

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 and had not seen
any examples of proof of concept code published when this security
bulletin was originally issued.


ADDITIONAL INFORMATION

The information has been provided by Microsoft Product Security.
The original article can be found at:
<http://www.microsoft.com/technet/security/bulletin/ms08-013.mspx>
http://www.microsoft.com/technet/security/bulletin/ms08-013.mspx



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