I haven't received any notification from ACM Computer and Communication Security yet, I'm a bit nervous
This can only be answered by conference organizers. From my own experience, many things can go wrong with organizing a conference, which can lead to delays. Most of this does not become otherwise obvious to the participants. As many first-time contributors tend to be nervous about the whole process generating many anguished questions, some conference organizers might not be too open about explaining delays on the conference website. In general, conference organizers have experience and will ensure that submitters will be treated reasonably. This implies that you will be informed if you are asked for a rebuttal.
You should give them more time.