South Korean computer security experts are bracing for more damage from a three-day old hacker attack that has been spreading like a virus and targeting government Web sites.
South Korean officials warned Friday tens of thousands of personal computers around the country may be on the verge of wiping out their own data.
It is the latest twist in a wave of cyber sabotage that entered its third day Friday, greatly slowing or blocking completely dozens of government, banking and other Web sites. Web sites in the United States have also been affected.
Jung Jin-sung is head researcher at Ahn Lab, one of South Korea's largest anti-virus software companies.
He says he estimates 30 to 60,000 personal computers have been infected so far.
Some public information about the cyber attacks has been emerging via lawmakers with contacts to South Korea's main intelligence agency. They say the virus has been traced to 86 Internet protocol addresses in 16 different countries, including both the United States and South Korea.
North Korea is not on that list. However, parliamentary intelligence committee member Chung Chin-sup says intelligence officials have Pyongyang in mind.
He says intelligence officials are presuming that North Korea is involved in the attack - but cannot provide details because the investigation is proceeding.
North Korea is on record last month as announcing it is "fully ready for any form of high-tech war." Yang Moo-jin, a professor at Seoul's University of North Korean Studies, says the North is no stranger to Web technology.
He says North Korean leader Kim Jong Il has been deeply interested for years in Internet networks as well as in cultivating the skilled human resources to deal with cyber warfare. He points out, the North Korean leader been building and expanding a North Korean Internet company since 2000.
Still, Yang is skeptical as to whether North Korea is technologically advanced enough to pull off such an attack. So is Kim Yoo-jung, a spokesperson for South Korea's left-leaning Democratic party.
She says there is no evidence of North Korea's involvement, and that the National Intelligence Service is not helping matters by making people anxious.
Regardless of who is behind the attacks, South Korea's main information security agency says visits to its anti-virus protection page have skyrocketed, with nearly 300,000 hits on Friday alone.