1. COM File extension is blocked - so file will not be scanned
2. This mislooking display only will be showed, when Astaro CA certificate is not installed. Maybe you installed it für windows in certificates.msc, but forgot to import the ca certificate into FF ? Firefox has it's own certificate management.
You probably imported the CA to your OS. My error message looked the same until I Imported the CA in Firefox. After importing the CA the message looks like it should look. But I´m using Windows.
I've suspended this at categorized it as "not a bug", since Sven is perfectly right: importing the HTTP Proxy Signing CA and giving it trust to identify websites should absolutely do this.
The website looks as described if the HTTP Proxy Signing CA is not imported or imported and not trusted.