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 FAQ below. Affected 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 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. Severity Rating: Windows 98 Critical Windows 98 Second Edition Critical Windows Me Critical Windows NT 4.0 Critical Windows NT 4.0 Terminal Server Edition Critical Windows 2000 Critical Windows XP Critical The above assessment is based on the types of systems affected by the vulnerability, their typical deployment patterns, and the effect that exploiting the vulnerability would have on them. Vulnerability identifier: CAN-2003-0010 Tested Versions: Microsoft tested Windows 98, Windows 98 Second Edition, Windows Me, Windows NT 4.0, Windows NT 4.0 Terminal Server Edition, Windows 2000, and Windows XP to assess whether they are affected by these vulnerabilities. Previous versions are no longer supported, and may or may not be affected by these vulnerabilities. Get more information about the exploit over here at the Microsoft Security Bulletin page. This hotfix has been added to our Windows XP Post SP1 Hotfix Chart.