Internet links restored in North Korea post country wide web outage, connection still spotty

North Korea experienced a complete Internet outage for hours before links were restored on Tuesday.

New Hampshire-based Dyn said the reason for the outage was not known but could range from technological glitches to a hacking attack. Several US officials close to the investigations of the attack on Sony Pictures said the US government was 'not involved' in any cyber action against Pyongyang.

US President Barack Obama had vowed on Friday to 'respond' to the major cyber attack, which he blamed on North Korea. Dyn said North Korea's Internet links were 'unstable' on Monday and the country later went completely offline.

"We're yet to see how stable the new connection is," Jim Cowie, chief scientist for the company, said in a telephone call after the services were restored. "The question for the next few hours is whether it will return to the unstable fluctuations we saw before the outage."

Also read: North Korea says it will boost nuclear power to counter hostile US policy

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 on Tuesday 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. North Korea is one of the most isolated nations in the world, and the effects of the Internet outage there were not fully clear.

Related: Internet outage seen in North Korea amid US hacking dispute

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. Almost all its Internet links and traffic pass through China, except, possibly, for some satellite links.

"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 in a report.

"And unlike these countries, North Korea maintains dependence on a single international provider, China Unicom," added the report.



NO PROOF, CHINA SAYS

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 administration officials told Reuters.

The US also asked China to identify any North Korean hackers operating in China and, if found, send them back to North Korea. It wants China to send a strong message to Pyongyang that such acts 'will not be tolerated', the officials said. By Monday, China had not responded directly to the US requests, the officials added.

In Beijing, the Chinese Foreign Ministry said on Monday it opposed all forms of cyberattacks and that there was 'no proof' that North Korea was responsible for the Sony hacking.

North Korea has denied it was behind the cyberattack on Sony and has vowed to hit back against any US retaliation, threatening the White House and the Pentagon..

Spotlight: Japan condemns Sony cyberattack, sees no impact on its North Korea talks

The hackers said they were 'incensed' by a Sony comedy about a fictional assassination of North Korean leader Kim Jong Un, which the movie studio has now pulled from general release.

"There's either a benign explanation - their routers are perhaps having a software glitch; that's possible. It also seems possible that somebody can be directing some sort of an attack against them and they're having trouble staying online," said Doug Madory, director of Internet analysis at Dyn Research.

Other experts said it was possible North Korea was attacked by hackers using a botnet, a cluster of infected computers controlled remotely.

Hacking fiasco: North Korea dismisses cyber attack allegations as 'groundless slander'

"It would be possible that a patriotic actor could achieve the same results with a botnet, however the President promised a proportional response," said Tom Kellermann, Chief Cybersecurity Officer at Trend Micro.

"The real issue here is that nonstate actors and rogue regimes will adopt this modus operandi in 2015. The use of destructive cyberattacks will become mainstream."

China is North Korea's only major ally and would be central to any US efforts to crack down on the isolated state. But the United States has also accused China of cyber spying in the past and a US official has said the attack on Sony could have used Chinese servers to mask its origin.