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AUSCERT External Security Bulletin Redistribution
ESB-2003.0586 -- Microsoft Security Bulletin MS02-040 REVISED
Unchecked Buffer in MDAC Function Could Enable System Compromise
21 August 2003
AusCERT Security Bulletin Summary
Product: Microsoft Data Access Components (MDAC)
Operating System: Windows
Impact: Execute Arbitrary Code/Commands
Access Required: Remote
CVE Names: CVE-2002-0695
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Title: Unchecked Buffer in MDAC Function Could Enable System
Released: 31 July 2003
Revised: 20 August 2003 (version 2.0)
Software: Microsoft Data Access Components 2.5
Microsoft Data Access Components 2.6
Microsoft Data Access Components 2.7
Impact: Run code of the attacker's choice.
Max Risk: Critical
Microsoft encourages customers to review the Security Bulletin at:
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Reason for Revision:
Subsequent to the release of this bulletin, it was determined that
the vulnerability addressed is not with the OpenRowSet command
(which is a Microsoft SQL Server command) but rather that the
vulnerability is with the underlying MDAC component Open Database
Connectivity (ODBC), which is present in all versions of Windows.
Additionally, the original patch released with this did not install
correctly on some systems because of a flaw in the way that
Microsoft Windows Installer updated the System File Protection
cache. The bulletin has been updated to include this additional
information and to direct users to an updated patch.
Note: The patch for this security bulletin has been superceded by
the patch in MS03-033. Customers who are seeking the patch for
MS02-040 should instead install the patch for MS03-033.
MDAC is a collection of components that are used to provide
database connectivity on Windows platforms. MDAC is a ubiquitous
technology, and it is likely to be present on most Windows systems:
By default, MDAC is included as part of Microsoft Windows XP,
Windows 2000, and Windows Millennium Edition.
MDAC is available for download as a stand-alone technology.
MDAC is either included in or installed by a number of other
products and technologies. For example, MDAC is included in the
Microsoft Windows NT(r) 4.0 Option Pack, as part of Microsoft Access,
and as part of SQL Server. Some MDAC components are also present as
part of Microsoft Internet Explorer even if MDAC itself is not
MDAC provides the underlying functionality for a number of database
operations, such as connecting to remote databases and returning
data to a client. Specifically, it is the MDAC component known as
Open Database Connectivity (ODBC) that provides this functionality.
A security vulnerability results because one of the ODBC functions
in MDAC that is used to connect to data sources contains an
unchecked buffer. An attacker could seek to exploit the
vulnerability by constructing a Web page that, when visited by the
user, could execute code of the attacker's choice with the user's
privileges. The Web page could be hosted on a Web site or sent
directly to the user in an e-mail message.
In the case of a system that is running SQL Server, an attacker
could seek to exploit this vulnerability by using the Transact-SQL
OpenRowSet command. An attacker who submits a database query that
contains a specially-malformed parameter within a call to
OpenRowSet could overrun the buffer, either to cause the computer
that is running SQL Server to fail or to cause the computer that is
running SQL Server to take actions that are dictated by the
- - - Users who read e-mail messages as plain text would have to take
an action before an attacker could exploit the vulnerability to be
- - - Systems that are configured to disable active scripting in
Internet Explorer are not affected by this vulnerability.
- - - In the Web-based attack scenario, a user would need to visit a
malicious web site under the control of an attacker. An attacker
would have no way to force users to visit a malicious Web site
outside the HTML e-mail vector. Instead, an attacker would need to
lure them there, typically by getting the user to click a link that
took them to the attacker's site.
- - - The privileges that are gained through a successful attack would
be equal to those of the application under which ODBC is running.
In most cases, an attacker would gain only the same level of
privileges as the logged on user.
- - - By default, Outlook Express 6.0 and Outlook 2002 open HTML mail
in the Restricted Sites Zone. In addition, Outlook 98 and 2000 open
HTML mail in the Restricted Sites Zone if the Outlook Email
Security Update has been installed. Customers who use any of these
products would be at no risk from an e-mail borne attack that
attempted to exploit this vulnerability unless the user clicked a
malicious link in the email.
A patch is available to fix this vulnerability. Please read the
Security Bulletins at
for information on obtaining this patch. Please note that this
patch is superceded by the patch available with
- - - David Litchfield, Next Generation Security Software Ltd.,
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THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.
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