Well I'm studying Computer science at unsw and the way we have it is in CS you get to choose a major. This is the area you 'specialize' in for your degree. I'm majoring in cyber security and I love this degree so I would definitely recommend it
Have a look at
https://www.handbook.unsw.edu.au/undergraduate/programs/2019/3778. In this you will find majors in Computer science including Networks and Cyber security. You can also see how some of the courses vary between them and what not.
If you wanna do those majors you have to choose Computer Science because I don't think SENG allows you to do it.