Title: Flaw in Windows Script Engine Could Allow Code Execution (814078) Date: 19 March 2003 Software: Microsoft Windows 98 Microsoft Windows 98 Second Edition Microsoft Windows Me Microsoft Windows NT 4.0 Microsoft Windows NT 4.0 Terminal Server Edition Microsoft Windows 2000 Microsoft Windows XP Impact: Run Code of Attacker's Choice Max Risk: Critical Bulletin: MS03-008 Microsoft encourages customers to review the Security Bulletins at: http://www.microsoft.com/technet/security/bulletin/MS03-008.asp http://www.microsoft.com/security/security_bulletins/ms03-008.asp - ------------------------------------------------------------------- Issue: ====== The Windows Script Engine provides Windows operating systems with the ability to execute script code. Script code can be used to add functionality to web pages, or to automate tasks within the operating system or within a program. Script code can be written in several different scripting languages, such as Visual Basic Script, or JScript. A flaw exists in the way by which the Windows Script Engine for JScript processes information. An attacker could exploit the vulnerability by constructing a web page that, when visited by the user, would 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 email. Although Microsoft has supplied a patch for this vulnerability and recommends all affected customers install the patch immediately, additional preventive measures have been provided that customers can use to help block the exploitation of this vulnerability while they are assessing the impact and compatibility of the patch. These temporary workarounds are discussed in the "Workarounds" section in the Frequently Asked Questions section of the security bulletin for this release. Mitigating Factors: ==================== - For an attack to be successful, the user would need to visit a website under the attacker's control or receive an HTML e-mail from the attacker. - Computers configured to disable active scripting in Internet Explorer are not susceptible to this issue. - Exploiting the vulnerability would allow the attacker only the same privileges as the user. Users whose accounts are configured to have few privileges on the system would be at less risk than ones who operate with administrative privileges. - Automatic exploitation of the vulnerability by an HTML email would be blocked by Outlook Express 6.0 and Outlook 2002 in their default configurations, and by Outlook 98 and 2000 if used in conjunction with the Outlook Email Security Update. Risk Rating: ============ - Critical Patch Availability: =================== - A patch is available to fix this vulnerability. Please read the Security Bulletins at http://www.microsoft.com/technet/security/bulletin/ms03-008.asp http://www.microsoft.com/security/security_bulletins/ms03-008.asp for information on obtaining this patch. - ------------------------------------------------------------------- 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.