The WebBrowser ActiveX control, or the Internet Explorer HTML rendering engine (MSHTML), as used in Internet Explorer 6, allows remote attackers to execute arbitrary code in the Local Security context by using the showModalDialog method and modifying the location to execute code such as Javascript, as demonstrated using (1) delayed HTTP redirect operations, and an HTTP response with a Location: header containing a "URL:" prepended to a "ms-its" protocol URI, or (2) modifying the location attribute of the window, as exploited by the Download.ject (aka Scob aka Toofer) using the ADODB.Stream object.