North Korea, at the centre of a confrontation with the United States over the hacking of Sony Pictures, experienced a complete internet outage for hours before links were restored yesterday, but US officials said that Washington was not involved.
US-based Dyn, a company that monitors internet infrastructure, said the reason for the crash was not known but could range from technological glitches to a hacking attack.
Several US officials close to the investigations into the targeting of Sony Pictures said the American government had not taken any cyber action against Pyongyang.
North Korea has significantly less internet to lose, compared to other countries with similar populations
US President Barack Obama vowed on Friday to respond to the major cyberattack, which he blamed on North Korea, “in a place and time and manner that we choose”.
Dyn said North Korea’s internet links were unstable on Monday and the country later went completely offline.
Links were restored at 0146 GMT on Tuesday. Possibilities for the outage could be attacks by individuals, a hardware failure, or even that it was done by North Korea itself, experts said.
Matthew Prince, CEO of US-based CloudFlare which protects websites from web-based attacks, said the fact that North Korea’s internet was back up “is pretty good evidence that the outage wasn’t caused by a state-sponsored attack, otherwise it’d likely still be down for the count”.
Almost all of North Korea’s internet links and traffic pass through China, which dismissed any suggestion that it was involved as “irresponsible”.
Meanwhile, South Korea, which remains technically at war with the North, said it could not rule out the involvement of its isolated neighbour in a cyberattack on its nuclear power plant operator.
It said only non-critical data was stolen and operations were not at risk, but had asked for US help in investigating.
South Korean President Park Geun-hye said yesterday the leak of data from the nuclear operator was a “grave situation” that was unacceptable as a matter of national security, but she did not mention any involvement of North Korea.
Their neighbour is one of the least-connected nations in the world, and the effects of the outage would have been minimal.
Very few of its 24 million people have access to the internet. However, major websites, including those of the KCNA state news agency, the main Rodong Sinmun newspaper and the main external public relations company went down for hours.
“North Korea has significantly less internet to lose, compared to other countries with similar populations: Yemen (47 networks), Afghanistan (370 networks), or Taiwan (5,030 networks),” Dyn Research said. “And unlike these countries, North Korea maintains dependence on a single international provider, China Unicom.”
The United States requested China’s help last Thursday, asking it to shut down servers and routers used by North Korea that run through Chinese networks, senior officials said.