(SEOUL, South Korea) -- North Korea may be off the hook as a suspect in Wednesday's cyber attack on South Korea that targeted major broadcasters and top banks.
While saying it could not totally rule out Pyongyang's involvement, Seoul admitted that no evidence was uncovered by the South Korean Internet and Security Agency that would point to the North as being behind the widespread computer failure.
South Korean officials admitted it could be days before the culprit is identified, if ever.
When users tried to open their individual computers on Wednesday, they said they saw three skulls on a black screen with the phrase "hacked by whoisteam." Some experts told ABC News that simply represents an unknown secretive group of hackers.
However, an investigation Thursday showed a Chinese Internet address may have been the source.
Systems at the South Korean military were not affected but the army has raised its defense level.
The cyber attack comes as tensions between the North and South have been raised by Pyongyang's recent detonation of an underground nuclear device and decision to abandon the armistice that ended the Korean War 60 years ago.
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