Software Engineering Institute

Windows Media Player 9 includes an ActiveX control that can be used to provide a playback interface for media objects on web sites. The ActiveX control does not adequately validate script access the Windows Media Library. From MS03-021:

The Windows Media Player 9 Series ActiveX control uses the Windows Media Player public object model, and provides access to the media library under certain conditions. The Windows Media Player 9 Series ActiveX control is a scriptable component, meaning that script code can be used to invoke or control it. The ActiveX control does not properly validate requests made by script to access the Media Library.

If a victim browses an attacker-controlled web site with Internet Explorer (IE), the attacker could read and modify information in the Windows Media Library and possibly determine the victim's username. The media library contains metadata about media objects such as title, duration, and artist and track names. By modifying an entry in the library (or creating a new entry), an attacker may be able to mislead a victim into opening a media object of the attacker's choice. In conjunction with other vulnerabilities, this could lead to more serious impacts, including the execution of arbitrary code.

Apply Patch

Apply the appropriate patch referenced in Microsoft Security Bulletin MS03-021. Based on the contents of the patch, the vulnerable ActiveX control is implemented in the file wmp.dll and the kill bit is not set for the vulnerable control. Under certain circumstances, it may be possible for an attacker to install a vulnerable version of the ActiveX control on a victim's system.

Disable Active scripting and ActiveX controls

Active scripting must be enabled for an attacker to exploit the Windows Media Player 9 Series ActiveX control in the manner discussed in MS03-021. A set of Internet Explorer zone security settings govern the behavior of ActiveX controls based on whether or not a control is signed, marked safe for scripting, or accessible via Active scripting. At a minimum, disable Active scripting and limit the functionality of ActiveX controls in the Internet zone and the zone used by Outlook, Outlook Express, or any other application that uses Internet Explorer or the WebBrowser control to render HTML. Instructions for disabling Active scripting and ActiveX controls can be found in the CERT/CC Malicious Web Scripts FAQ.

Apply the Outlook Email Security Update

Another way to effectively disable Active scripting and ActiveX controls in Outlook is to install the Outlook Email Security Update. The update configures Outlook to open email messages in the Restricted Sites Zone, where Active scripting and ActiveX controls are disabled by default. In addition, the update provides further protection against malicious code that attempts to propagate via Outlook. The Outlook Email Security Update is available for Outlook 98 and Outlook 2000. The functionality of the Outlook Email Security Update is included in Outlook 2002 and Outlook Express 6.