"All of these things have happened and there's a potential, therefore, for them to happen into the future."
GEN Campbell also noted that there has been an "extraordinary up-tick" in cyber crime, which includes international espionage, economic theft and corporate crime, and pointed out that the internet is currently "ineffectively governed".
The Chief of Defence avoided pointing fingers at any specific country, saying it's more of a global issue than any one nation.
"The question at play nationally is how do we appropriately build some effective governance mechanisms without losing the value we all appreciate from the internet," GEN Campbell said.
"This is a really important part of the modern evolution of our societies, our economies and our body politic."
China, Russia, Iran and North Korea account for the majority of "significant cyber incidents" worldwide, and as recently as last month, Chinese hackers were discovered having compromised the European Union's communication systems, allowing them access to sensitive information for several years.
The US, alongside Australia, Canada, the UK and New Zealand accused China in December of conducting cyber espionage against companies across 12 countries for over a decade, and saw the indictment of two hackers associated with the campaign.