SEOUL—When the North and South Korean leaders vowed on April 27 to cease all hostile acts against each other, many saw it as a turning point in cross-border relations and a step toward a new era of peace.
In the weeks since their agreement, the North ramped up its campaign of cyberattacks on South Korea, launching fresh assaults on financial companies and groups focused on North Korea, according to people familiar with the matter. The frequency of those attacks also increased this month, one of the people said.
The latest wave of hacking shows how the Kim regime extended a longstanding pattern of aggressive behavior toward Seoul despite publicly pledging warmer relations as it prepared for a summit with President Donald Trump. The U.S. called off the summit Thursday in response to new threats from Pyongyang.
The South Korean government is reviewing the cyberattacks, which started in the lead-up to the inter-Korean summit in April and continued through at least Wednesday, the people said. Early indications, based on the malware and targets, strongly suggest North Korea was the culprit, the people said.
The groups targeted include South Korean financial companies and organizations that focus on North Korea, the people said, with hackers seeking sensitive information. As with nearly all cyberbreaches, it is unclear how many computers were infected or what precisely was stolen.