Microsoft has issued a pre-patch security advisory to warn about "active, targeted attacks" against an ActiveX control for the Snapshot Viewer for Microsoft Access.
An attacker could exploit the vulnerability by constructing a specially crafted Web page. When a user views the Web page, the vulnerability could allow remote code execution. An attacker who successfully exploited this vulnerability could gain the same user rights as the logged-on user.
The ActiveX control for the Snapshot Viewer for Microsoft Access enables you to view an Access report snapshot without having the standard or run-time versions of Microsoft Office Access. The vulnerability only affects the ActiveX control for the Snapshot Viewer for Microsoft Office Access 2000, Microsoft Office Access 2002, and Microsoft Office Access 2003.
The ActiveX control is shipped with all supported versions of Microsoft Office Access except for Microsoft Office Access 2007. The ActiveX control is also shipped with the standalone Snapshot Viewer.
The advisory contains information on setting the killbit to avoid the attack. More information in this US-CERT advisory.