Is Trick or Treat on Halloween Published on October 31, 2016?

CNN's John Sutter says he thinks the hackers are either American or foreign. The first message was published on October 31, 2016 and labels itself "trick or treat" He believes it could be someone who knows enough about U.S. culture to know that Halloween is a big thing here. But if they're trying to hide their identity, saying trick or treat might not go over well.