This was re-rum on some PBS stations in the USA.
The is not recent news, but is the most important thing this year and last year.
 Massive Cyber Attacks are no only possible, it is happening.  Here is a disturbing report for PBS.
http://www.pbs.org/wgbh/nova/next/military/snowden-transcript/
The title is:
Exclusive: Edward Snowden on Cyber Warfare
By James Bamford and Tim De Chant on Thu, 08 Jan 2015

The fact that the report is-from last year does not reduce the import of this subject. lease read it and think about it.   
 
If you can find the PBS video, it shows how an attack was sent against a  high security nuclear facility that has no Internet.In a cyber attack, i dont see there being any winners just a bunch of losers. If one were to happen it would likely just CHOKE up the internet with nonsense to bring it to its knees. Thing is that with DDoS attacks they can generally be located and blocked with the right hardware that is able to associate packet origin being that from a DDoS attacker.

The big online game companies out there frequently get attacked and are able to put a stop to the outages.

Biggest concern is with automation being taken over through a hack such as power grid controls, but this is quite a stretch to pull off if its even possible. Years ago I read about a short outage that was the result of some hackers. Hopefully the system has been hardened since to block this problem.

Without electricity just about everything comes to a halt. Gas stations cant pump gas without it etc unless they have a generator etc. But fact is that manual overrides I am sure are still in PLACE for power grids to in an emergency adapt quickly and bringing it back online. Nuke power plants also while automated are very offline for the most part from what I have read as well and so its not as if a hacker would be able to force one to operate outside of its safe operating conditions as well. Many fail safes.

The stock market being down for a bit might cause a slump but everything would be back to NORMAL once the DDoS attack is snuffed out etc.

Zero-Day attacks additionally while bad if one was discovered and exploited; due to a very diverse range of systems out there running many different operating systems, the exploit would only be able to target a specific group or family of systems but not all. The best attack would be one that targets all systems connected to the internet no matter of hardware and operating system. Currently only DDoS attacks work in such a way to target all hardware no matter of make etc.

I personally am not worried about this. There are very good tools and configurations in place to prevent issues or minimize the problems.

The only CyberAttack the US has to worry about is from a huge solar flare...from which there is absolutely no defense stopping it...

So why worry.OK. Don't worry.  Anyhow, worry would not help.
In the interview Edward Snowden on Cyber Warfare the point was made that international cyber attacks have taken place and can not be be fully documented.

These attacks are not for a few individuals wanting  to make a point. Rather, they are international secret government fabricated asphalts on specific targets. Some details did get to the media, but the evidence was not the kind of proof that most people would find conclusive. It looked liked something unlikely had happened and nobody was at fault.

To get the point, one has to watch the PBS documentary and pay attention.

Of course if you don't believe it, it makes no difference.  Nothing you or I do will stop it.  Someday in the near future some important thing will fail, blow up of otherwise put a  heavy load on some nation or state. And it will look like an unlikely happenstance. And thee will be almost no trace of the cyber attack.

The alternative is to have nothing run by any kind of electronic controller. And that will never happen until it no longer matters.

Here is yet another site that talks about the overall idea.
https://home.kpmg.com/si/en/home/insights/2016/05/how-vulnerable-are-governments-to-cyber-crime.html
But it only  looks at  the organized crime aspect. The big danger is from government organizations. Here is a more specific document.
http://www.infosecurity-magazine.com/opinions/how-can-you-fend-off-a-nation/
Title:  How Can You Fend Off a Nation? 
by Gavin Millard Technical DIRECTOR at Tenable Network Security.
Rather giving a short quote, I recommend you u spend three minutes reading his article. He is real serious.
Quote from: Geek-9pm on June 09, 2016, 05:17:33 PM

the point was made that international cyber attacks have taken place and can not be be fully documented.

Of course if you don't believe it, it makes no difference.  Nothing you or I do will stop it.  Someday in the near future some important thing will fail, blow up of otherwise put a  heavy load on some nation or state. And it will look like an unlikely happenstance. And thee will be almost no trace of the cyber attack.

I recommend you spend three minutes reading his article. He is real serious.

Before suggesting the improbable you have to eliminate the probable. You can't just jump right to some ridiculous explanation when much more simple explanations exist for something.

... There is little concrete proof of involvement of the Russian Federation
government in any cyber attacks. The circumstantial evidence does lead to
the perception that the Russian government was behind or supported
recent cyber attacks. When countries or organizations stand in opposition to Russia they are likely to receive a cyber attack in order to influence their position.
The high likelihood of future cyber attacks, the ease of conducting cyber attacks,
and the amount of networks to conduct the attacks make this monograph relevant for study.
Government and organizational leaders need to ensure that their cyber defenses are ready to  protect private information, ...