Safely hang a mirror that does not have hooks

I would like to safely secure a mirror to the drywall. The mirror itself is pretty light (probably under 5kg), the weight is not an issue. However, its back surface does not have any hooks or anything that can be used to secure it. I was going to use a string and some nails, but I am not sure it will work, the wooden part is really thin. Any ideas? Perhaps, some adhesive tape?

UPDATE

Thanks everyone for your answers. All of them are great, it's hard (perhaps, impossible) to pick the best one. Because the mirror is light, I decided to use a wire and small eye bolts attached to the sides of my mirror.