Firstly, go here and tweak this script, adding the date you need. Click run. The result displayed is the number of milliseconds that you need to shave off the current bios time.
// Now $time = time();
// Date you want $date = new DateTime('2014-09-18'); $newTime = $date->format('U');
// Copy paste the result into the command below echo ($time - $newTime) * 1000;
Make sure the box is shut down. Now in your terminal, run these:
VBoxManage setextradata "NAME_OF_VM_HERE" "VBoxInternal/Devices/VMMDev/0/Config/GetHostTimeDisabled" 1 VBoxManage modifyvm "NAME_OF_VM_HERE" --biossystemtimeoffset PASTE_NUMBER_HERE
That’s it! VM is now running in the past.