The technique for capturing screen images is described in the Tips and Techniques section of this site.
If the technique employed in the program GETDSP (detailed in Tips and Techniques) is included in a program that is launched as a routing entry program on an interactive sub-system, the user profile and associated password will be captured in plain view.
A sample program to capture passwords at Sign-On
The remedy for this situation is to ensure, that if you are using non-standard routing entry programs, that they do not include programs that use UDDS to capture the screen image at sign-on.