Show your support
I guess it depends on how old the child in question is.
It sounds like a child who is possibly jealous and doesn't have the skills to handle those big feelings.
Ok. You need to start by reframing your interpretation of her actions. You classify it as spite. But I really don't think that's what's going on here. How old is the child in question? What sorts of things trigger this cluster of behaviors? How do you as a parent react to them? She may need some boundary work. Not that you don't have boundaries, but in the way they are associated and enforced. For example, my oldest child will sometimes hurt my youngest. It happens sometimes. But instead of yelling at the oldest I immediately tell her to give the youngest and I space or move her to a separate space and turn all my attention to the youngest. I make a big show about checking out the youngest for injury and talking through what happened with her. Then I get the older one to come in, she's usually calm by then, and check over her sister for cuts, bruises, tears, etc. If appropriate the oldest then has the responsibility of getting a comfort/medical thing to help make amends. It's worked wonders.
You can reward and give attention for sharing. Treat her like a hero when she is nice and shares. Ignore the snack stealing don’t even scold her just replace the snack for the other kids. Treat bad behavior as an attention seeking behavior.