SEOUL, March 25 (Yonhap) -- South Korean banks are raising their alertness level against potential cyber attacks by beefing up online security following last week's massive computer network paralysis at some banks, officials said Monday.
Their efforts to strengthen online security in the financial system came after computer networks at Korea's major broadcasters, banks and insurers were shut down on Wednesday due to malicious codes.
Korea's No. 3 lender Shinhan Bank, NongHyup Bank and Jeju Bank were hit by the cyber attacks, seeing financial services halted and crippling operations for hours.
Local banks went into emergency mode on Monday and the financial watchdog instructed them to raise their alertness level as an increase in financial transactions is anticipated in the final week of March, officials said.
"The network paralysis at banks last week proved our vulnerability in the financial sector," said Shin Je-yoon, the chairman of the Financial Services Commission.
"We need to make sure it doesn't happen again by finding out the exact causes through a thorough investigation."
Seoul's communications watchdog said Friday that some of the malicious code used for the hacking attacks originated from a local computer of NongHyup Bank, not from China. Earlier on Monday, local police said some of the malicious code originated from the United States and three European countries.
NongHyup, which also suffered from similar cyber attacks in April 2011, is on high alert as it has detected some signs of potential attacks from its crippled computer networks during the checkup, according to officials.
NongHyup said it cut off access to outside networks to prevent potential hackers from accessing its internal networks and strengthened the degree of online firewalls.
Shinhan Bank added that it also reviewed its financial system and instructed its employees to be prepared for emergency situations amid speculations over additional attacks.
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