Just stuck into that myself. What I did:
Set up port forwarding in VirtualBox (network settings) from 0.0.0.0:22 guest to 127.0.0.1:2222 host.
Edited /etc/ssh/sshd_config on guest and uncommented Port 22.
Restarted sshd on guest: sudo service sshd restart
Stopped iptables on guest (might be unnecessary): sudo service iptables stop
Connected from host using line:
ssh -p 2222 -o "UserKnownHostsFile=/dev/null" -o "StrictHostKeyChecking=no" cloudera@127.0.0.1
SCP command will be:
scp -P 2222 -o "UserKnownHostsFile=/dev/null" -o "StrictHostKeyChecking=no" phone_fb_big.csv cloudera@127.0.0.1:~