get control handle without controlID

Hey,
struggling to get the handle of a control.
I am trying to fill the login-form of an application that loads an IE frame inside a standard window. In “Autoit Window Info” the IE frame is listed under “control”. As far as I can comprehend… I would need the control handle to create the IE object.

I already got the handle of the surrounding window… but I am unable to receive the control handle because there is no controlID listed.

ControlGetHandle ( "title", "text", controlID )

Does somebody know how I can solve this problem?

Thank you!