Hacking a computer may be illegal or not depending on each countries Laws and what you mean by hacking. Anyway, it's against G-d's Law for both Jews and Gentiles (hacking or even cheating to get accesss to personal data) whether it is forbidden by the civil/penal law or not. If it is illegal in your country, then it adds another violation to Jewish Halacha which orders Jews to abide by the Law of the country, and generally it also adds a violation to Gentiles who are commanded to establish and obey courts of justice. (It may be permitted in cases when it is done to prevent a greater evil or to protect Jews, I don't know if this case could be considered permitted)
But what has this post got to do with Righteous Gentiles?