CERT Advisory CA-2002-33 Heap Overflow Vulnerability in Microsoft Data

From: CERT Advisory (cert-advisory@cert.org)
Date: 11/21/02

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    CERT Advisory CA-2002-33 Heap Overflow Vulnerability in Microsoft Data
    Access Components (MDAC)

       Original release date: November 21, 2002
       Last revised: --
       Source: CERT/CC

       A complete revision history can be found at the end of this file.

    Systems Affected

       All Microsoft Windows systems running the following:
         * Versions of Microsoft Data Access Components (MDAC) prior to 2.7
         * Internet Explorer version 6
         * Internet Explorer version 5.5
         * Internet Explorer version 5.1

       Note that Microsoft Windows XP is shipped with MDAC version 2.7 and is
       not vulnerable by default even though Internet Explorer 6.0 is

       Because the normal operation of several applications and web servers
       on a system depend on the proper operation of the MDAC ActiveX
       control, other programs could be used as an exploit vector. For
       example, Internet Information Server may be configured to use MDAC.


       A vulnerability in the Microsoft Data Access Components (MDAC) could
       lead to remote execution of code with the privileges of the current
       process or user.

    I. Description

       Microsoft Data Access Components (MDAC) is a collection of utilities
       and routines to process requests between databases and network
       applications. A buffer overflow vulnerability exists in the Remote
       Data Services (RDS) component of MDAC.

       The RDS component provides an intermediary step for a client's request
       for service from a back-end database that enables the web site to
       apply business logic to the request.

       According to Microsoft's Security Bulletin MS02-065, a routine in the
       RDS component, specifically the RDS Data Stub function, contains an
       unchecked buffer. The RDS Data Stub function's purpose is to parse
       incoming HTTP requests and generate RDS commands. This unchecked
       buffer could be exploited to cause a heap overflow.

       There are two ways in which this vulnerability can be exploited. The
       first involves an attacker sending a malicious HTTP request to a
       vulnerable service, such as an IIS server. If RDS is enabled, the
       attacker can execute arbitrary code as the IIS server. RDS is not
       enabled by default on Windows 2000 and Windows XP systems. It can be
       disabled on other systems by following the advice in Microsoft's
       security bulletin.

       The other way to exploit this vulnerability involves a malicious web
       site hosting a page that exploits the buffer overflow in the MDAC RDS
       stub through a client application, such as Internet Explorer. Most
       systems running Internet Explorer on operating systems other than
       Windows XP are vulnerable to this attack. The attacker is able to run
       arbitrary code as the user viewing the malicious web page.

       Both web servers and client applications that rely on MDAC are
       affected. It is recommended that all users of Microsoft Windows 98,
       Windows 98 SE, Windows ME, Windows NT 4.0, and Windows 2000 apply the
       patch (Q329414). Windows XP users are not affected since MDAC 2.7, the
       non-vulnerable version, is installed by default.

       Information about this vulnerability is discussed in VU#542081. This
       issue is also being referenced as CAN-2002-1142.

    II. Impact

       A remote attacker could execute arbitrary code with the privileges of
       the application that processed the request.

       In the case of a web server or other service, this is likely to be the
       SYSTEM or another account with elevated privileges. In the case of a
       client application, this will be the account used to view the web

    III. Solution

     Apply a patch from your vendor.

       Microsoft has released a patch (Q329414) and a security bulletin
       (MS02-065) to address this issue. An end-user version of MS02-065 is
       available at

       According to the Microsoft advisory, a scenario exists in by which a
       vulnerable version of the control may be re-installed on a Windows
       system even after the patch has been applied. This is due to the fact
       that the vulnerable ActiveX control is signed by Microsoft and the
       patch does not set the kill bit for the MDAC control.

       This vulnerability was reported in an advisory by Foundstone and in
       MS02-065 by Microsoft.

       Feedback can be sent to the Authors: Jason A. Rafail, Chad R.
       Dougherty, and Cory F. Cohen.

       This document is available from:

    CERT/CC Contact Information

       Email: cert@cert.org
              Phone: +1 412-268-7090 (24-hour hotline)
              Fax: +1 412-268-6989
              Postal address:
              CERT Coordination Center
              Software Engineering Institute
              Carnegie Mellon University
              Pittsburgh PA 15213-3890

       CERT/CC personnel answer the hotline 08:00-17:00 EST(GMT-5) /
       EDT(GMT-4) Monday through Friday; they are on call for emergencies
       during other hours, on U.S. holidays, and on weekends.

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       Copyright 2002 Carnegie Mellon University.

       Revision History
         November 21, 2002: Initial release

    Version: PGP 6.5.8

    -----END PGP SIGNATURE-----

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