CVE-2004-1686

Vulnerability

Internet Explorer 6.0 on Windows XP Service Pack 2 fails to properly handle a specially crafted comment placed between the DOCTYPE declaration and the ` tag in an XHTML document. The comment must follow the format <!-- saved from usr=(XXXX)URL -->`, mimicking comments added by Internet Explorer when saving a page. This allows remote attackers to bypass the Information Bar prompt that normally blocks ActiveX controls and JavaScript execution, as demonstrated using the DesignScience MathPlayer ActiveX plugin [1]. The vulnerability affects IE 6.0 on Windows XP SP2.

Exploitation

An attacker can host a malicious XHTML page containing the crafted comment and lure a user to visit it. No authentication or special network position is required; the user only needs to browse to the page. Upon loading, the Information Bar does not appear, and ActiveX controls (e.g., the MathPlayer plugin) or JavaScript execute without user consent. The attacker can embed arbitrary ActiveX objects or scripts.

Impact

Successful exploitation allows the attacker to execute arbitrary ActiveX controls and JavaScript in the context of the user's browser session. This can lead to remote code execution, data theft, or further system compromise, depending on the capabilities of the loaded ActiveX control. The attacker gains the same privileges as the user.

Mitigation

No official patch or workaround is disclosed in the available reference. Users could mitigate the risk by disabling ActiveX controls or using a different browser. As this vulnerability is from 2004, later versions of Internet Explorer and Windows updates likely addressed the issue, but no specific fix is mentioned.