virtualbox.org

Is there a way to access/browse the virtual hard drive like a file manager while the guest OS is off?

For example, if I want to browse to a folder and drop a file, then load the guest OS. I don't want there to be a way for the guest OS to see the host OS's files (not even a 'shared folder' space), but I want the host OS to be able to see the guest OS's files. Basically, strictly one-way with the guest OS having no knowledge of any shared area or the host OS.

Afaik, only with a live CD iso and the appropriate vdi as second disk.

You can set up a network share (not a VBox Guest Additions share) in which the shared folder is on the guest drive. You don't have to share anything on the host drive. A host only network connection should give the host access to the guest. E.g. if you shared the guests root folder this way then you'd have access to the entire guest drive: not normally recommended.