What challenges does the united nations face in protecting human rights?

The UN has only limited power over what happens in the particular coutries, and cannot intervene unless with a very risky military operation or sanctions, which can bring about more suffering. So in many cases, when there is no cooperation from the state where human rights abuse take place, there is not much the UN can do. And the particular states' representatives can benefit from human rights abuse thought corrupt or undemocratic government, if the government  officials themselves profit e.g. from slave labour.