"In the U.S. alone, government and private targets are pummeled by hundreds of thousands of hacking attempts every hour. Cyberattackers have breached the Pentagon, State Department, and White House; stolen the personal data of an estimated one half of Americans in attacks on banks and tech companies like Yahoo; and provided WikiLeaks with the personal emails of Democratic Party officials, as well as generals and former secretaries of state....."
".....most hacks are directed or sponsored by nation states; the two worst culprits are China and Russia. China's mysterious Unit 61398, part of the People's Liberation Army, has reportedly been responsible for at least 141 successful cyberintrusions on 20 major U.S. industrial sectors, including oil and gas pipelines. In Russia, hacking groups called Cozy Bear and Guccifer 2.0 have targeted foreign critics of President Vladimir Putin, and in December shut down part of the electric grid in Ukraine."
"About 91 percent begin with a simple phishing attack, in which an email masquerading as a legitimate communication from a well-known company invites the recipient to click on a link or open an attachment. That attachment or link is actually loaded with malware. If just one of the hundreds of people in a company or government agency targeted by this attack falls for the trick, his or her computer downloads that malware — giving the hacker a back door into the organization's entire network...."
What would cyberwar look like?
It would be silent but enormously destructive. The two sides could block access to the Global Positioning System, disrupt air traffic control and electric grids, and block access to the internet or fill popular websites with propaganda — causing widespread chaos and fear. Cyberwar is the only field of warfare in which the U.S. doesn't have a clear advantage over its foes, warned then–Joint Chiefs Chairman Martin Dempsey before he retired last year. "It's a level playing field," said Dempsey, "and that makes this chairman very uncomfortable."
The Hacking Epidemic: