Hackers have hit several South Korean banks and broadcasters, paralysing their computer systems, according to reports.
The Yon Hap news agency reported that South Korean broadcasters KBS, MBC and YTN had been crippled by attacks.
The agency also reported that country's Shinhan Bank and Nonghyup's networks were also affected by cyber attacks.
The nature of the attacks and their purpose remain unknown, though staff at the three broadcasters reported that crashed computers were locked to an error screen and could not be restarted, according to the BBC.
Unconfirmed reports suggest the Shinhan bank attack affected the firm's internet banking services and ATM machines.
The South Korean government is reportedly investigating the attacks and already suspects they stemmed from North Korea.
Stonesoft director of cyber security, Jarno Limnell added if North Korea is responsible the fallout could be disastrous.
"If North Korean agencies are responsible, this is the latest step in an escalation of cyber-attacks made across the Korean peninsula in recent months," said Limnell.
"The choice of targets is telling of the trend that the chief candidates for attack are increasingly likely to be global financial markets and critical infrastructure systems, which if taken down have the power to cripple a nation.
"In today's digitally interconnected world there is huge potential for unpredictable side effects and collateral damage from aggressive actions. As such, fighting fire with fire is a dangerous tactic."
LogRhythm vice president, Ross Brewer warned of the dangers of blaming North Korea without substantial proof.
"There remains an enormous amount of uncertainty surrounding the origins of the attack," said Brewer.
"Without confirmation of the source of cyber attacks, inaccurate finger-pointing can and often occurs - and given the current diplomatic tensions between South and North Korea, this can lead to unwanted military involvement."
North Korea, South Korea and the US have been engaged in a heated war of words about their respective cyber activities.
Most recently North Korea accused the US of launching a series of hacking attacks against its networks on 15 March.