koreaherald.com - Seoul Guarantee Insurance, South Korea's largest provider of guarantee insurance, has been crippled by a ransomware attack, with its core systems offline for a third straight day.

The incident began early Monday, when SGI reported an “abnormal symptom” in its database system. By Tuesday afternoon, a joint investigation by the Financial Supervisory Service and the Financial Security Institute confirmed it was caused by a ransomware breach.

As a pivotal player in Korea’s guarantee insurance industry, SGI’s disruption is generating widespread confusion and inconvenience. The insurer provides guarantees for both individuals and corporations, with a guarantee balance of 478 trillion won ($344.4 billion) as of end-2024.

The impact is particularly severe in the housing market, where many rely on guarantee insurance for the “jeonse” rental system, where renters pay a large, refundable deposit in exchange for no monthly rent. SGI is one of the leading providers in this space, offering the highest cap on jeonse loan guarantees at 500 million won, compared to 200 million to 400 million won from other institutions.

While some services have been restored through cooperation with financial institutions, SGI’s main data system remains inoperative as of Wednesday morning. In urgent cases, the company has resorted to issuing handwritten guarantee certificates to minimize disruption.

Starting Wednesday, the insurer is operating an emergency center to collect reports of consumer damage and support recovery. “We vow full compensation and are planning responsible follow-up measures,” said SGI President and CEO Lee Myung-soon.

This is the first full-system disruption at a Korean financial institution caused by a ransomware attack and a second such case involving a Korean company this year. In June, major online bookstore Yes24 experienced a five-day outage and an estimated 10 billion won in lost sales due to a similar breach.