Hi,
I'm only using an IFRAME for showing the recent donations :-)
The URL is: http://plugin-info.arnebrachhold.de/donor-list.php
Can you show me the exact error message or the result of the Exploit Scanner? The plugin also NEVER modifies the frontend (it's actually not even active on a normal page load for saving memory) so I doubt it is the source of this error.
I would be glad to assist you in resolving this issue, you can also contact me by mail if you have any questions. (arne AT arnebrachhold de)
Thanks,
Arne
Edit: I've just installed the scanner and indeed it finds the iframe in the plugin, in the same way it finds one in the Akismet plugin for displaying the statistics.
If you don't like this small window which shows the recent donations, you can click on the "Hide this list" link under it and it will never be shown again.
Additionally I want to note that the scanner is very simple (yet). If I would really want to hide this iframe and trick you, I could just create it via Javascript and the scanner would never be able to find it.