use 5.012;
use warnings;

use POSIX qw(mktime difftime);

use constant {
    VBoxManage => 'C:\Program Files\VirtualBox\VBoxManage.exe',
    # Enter correct date here, example is 1913-12-11 14:15:16 UTC
    reftime => mktime(16, 15, 14, 11, 12, 1913)
};

my $delta = difftime(time, reftime);

if (system(VBoxManage, 'modifyvm', 'Beta-VM', '--biossystemtimeoffset', $delta) != 0) {
    die "Failed to run VBox management command";
}