I had a hell of a time the other day trying to find a reasonably up to date Debian Jessie virtual machine for testing on.
It doesn't take too long to install Debian, but its much nicer to just grab an OVA file, open with virtualbox and be ready to go.
I have only installed a very minimal system, though I did set up sudo, vim and git (which it is hard to live without)
The user is called user (password resu) and the root user is called root (password toor). Obviously this is for use in testing. Change the passwords if you put it somewhere that others may find it.