PYEONGCHANG - Pyeongchang Winter Olympics organizers confirmed on Sunday that the Games had fallen victim to a cyber attack during Friday's opening ceremony, but they refused to reveal the source.The Games' systems, including the internet and television services, were affected by the hack two days ago but organizers said it had not compromised any critical part of their operations."Maintaining secure operations is our purpose," said International Olympic Committee (IOC) spokesman Mark Adams."We are not going to comment on the issue. It is one we are dealing with. We are making sure our systems are secure and they are secure."Asked if organizers knew who was behind the attack, Adams said: "I certainly don't know. But best international practice says that you don't talk about an attack."