Well, most moral philosophies usually hold some very basic things as wrong, murder and stealing being among them.
However, the issue is that it's very culturally dependent on WHY it's seen as wrong, and it's the reason behind WHY something is seen as wrong that the more complex elements of ethics are built on.
A utilitarian vs a deontologist vs a virtue theorist vs a follower of almost any religion vs a supporter of god knows how many other moral theories I don't know about would all have a different answer to that, and different answers to which cases killing or stealing or anything else might potentially be justified/right.
And you can see that reflected in legal systems of different countries right now. Some countries have self defence as basically 'anything is permissible if they're intruding on your property' where some have it so you need to use reasonable force. Some countries consider it fair to let the government kill criminals via the death penalty, and others don't.
The difficulty isn't defining whether murder or theft or what not in its most blatant forms is wrong, since most ethical frameworks will state it is. It's trying to define the many, many edge cases that people don't agree on, and which many countries/states/societies take different approaches to.