SEOUL — Investigators have traced a coordinated cyberattack that paralyzed tens of thousands of computers at six South Korean banks and media companies to a Chinese Internet Protocol address, but it was unclear who orchestrated the attack, authorities in Seoul said Thursday.
The discovery did not erase suspicions that North Korea was to blame. An IP address can provide an important clue as to the location of an Internet-connected computer but can be manipulated by hackers operating anywhere in the world. The investigation into Wednesday’s attack could take weeks.
By Thursday, only one of the six targets, Shinhan Bank, was back online and operating regularly. It could be next week before the other companies have fully recovered.
North Korea has threatened Seoul and Washington in recent days over UN sanctions imposed for its Feb. 12 nuclear test, and over ongoing US-South Korean military drills. It threatened revenge after blaming Seoul and Washington for an Internet shutdown that disrupted its network last week.
North Korea “will never remain a passive onlooker to the enemies’ cyber attacks,” state media said last week. “The US and its allies should be held wholly accountable for the ensuing consequences.”
Wednesday’s cyber attack did not affect South Korea’s government, military, or infrastructure, and there were no initial reports that customers’ bank records were compromised. But it disabled scores of cash machines, disrupting commerce in this tech-savvy, Internet-dependent country, and renewed questions about South Korea’s Internet security and vulnerability to hackers.
The attack disabled some 32,000 computers at broadcasters YTN, MBC, and KBS, as well as three banks. Many computers were still down Thursday, but the broadcasters said their programming was never affected, and all ATMs were back online except for those at 16 Nonghyup Bank branches.
The attack may have extended to the United States. The website of the US-based Committee for Human Rights in North Korea also hacked, with reports on satellite imagery of North Korean prison camps and policy recommendations to the US government deleted from the site, according to executive director Greg Scarlatoiu.
The initial findings from South Korean investigators were based on results from an investigation into one target, Nonghyup Bank. The investigation is continuing into the shutdown at the five other firms.
A malicious code that spread through the Nonghyup server was traced to an IP address in China, said Cho Kyeong-sik of the Korea Communications Commission. Regulators said all six attacks appeared to come from “a single organization.”
The Chinese IP address identified by the South Korean communications regulator belongs to an Internet services company, Beijing Teletron Telecom Engineering Co., according to the website tracking and verification service Whois.
North Korea has threatened retaliation for UN sanctions.