Even though many Western network infrastructures are more robust than Estonia's, hactivism and other politically motivated attacks are still a worry for CIOs, Witt said.
"We have worked diligently with our critical infrastructure owners and operators, whether in the telecom industry or the IT industry or the chemical or energy sectors," Witt said. "We've been working at this for many years to make sure we have a more robust type of backbone to deal with this kind of attack. Is that to say we are 100 percent protected against this type of attack? Absolutely not. It all comes back to best practices and having plans in place to deal with attacks."
What will happen next?
Security experts predict that politically motivated attacks will be more targeted than all-out cyber war aimed at taking down the internet.
"What motive would Russia or China have to try to take out the US suddenly? If they do that, they're going to get hurt, too," Bellovin said. "If they take out the internaps, they take them out for themselves, too. If they take out our economy, they take out some of their big trading partners, which hurts them, too. There's not an obvious motive for something happening on that scale in the very near future."
Bellovin said the more likely scenario is that hactivists or cyber terrorists would disrupt individual commercial or government targets.
"What if someone said: Pay us $100 million or the denial-of-service attack that took out the electrical grid in California is going to happen again?" Bellovin asks. "That would be an act of war. And from a military perspective, every major country is looking at attacks and defences on this issue."
Kaplan said politically motivated attacks are more likely to come in the form of spear phishing attacks rather than DoS attacks like those used against Estonia.
"If I want to steal a piece of information from a particular company or government, I just look around at publicly available information such as Google, find the controller of that information, and send that particular person a phishing email," Kaplan explains. "He's the only one who gets it, and it's specific enough that he opens up. I can't do that on a mass scale, but I can do it to get deep into a particular organisation."
Kaplan also worries about hard-to-detect polymorphic viruses and malware hiding in virtualisation engines.
"This is not to say that a big cyber war attack couldn't happen," Kaplan adds. "But when I think about what a group of kids or terrorists could do, there are so many other options that are more attractive than all-out governmental cyber warfare."
Experts say what will happen next in cyber war is that hactivists will launch whatever kinds of attacks - DoS, web defacements, worms, viruses, phishing or pharming - that help them meet their goals.
"It's an arms race. I would never predict what the next bad thing will be," Lindner said. "The best thing that a corporation or anyone can do is have a good layered defence, understand their exposures and have a good plan for managing the attacks when they occur."
Most of the steps that CIOs should take to prepare for hactivism involve keeping up with state-of-the-art security practices. And these steps will protect networks from both political and profit-driven attacks.
"You shouldn't neglect politically motivated attacks as a threat, but you should be worrying much more about the economic impact today," Bellovin said. "Most of the things you should do about that would help to protect you against this threat as well."