SEOUL, July 30 (Yonhap) -- South Korea's privacy watchdog said Thursday it has fined wireless carrier KT Corp. 53.9 billion won (US$37.4 million) over a major data breach that affected more than 16,000 users.

The Personal Information Protection Commission also ordered KT to take corrective measures over the breach into the company's wireless network through unauthorized mobile base stations.

The breach, first reported by the company in September, affected phone numbers and mobile device identification numbers of 16,647 users, according to the regulator.

Malicious actors then used the information to carry out unauthorized transactions, leading to losses of 240 million won in total for 368 victims.

The watchdog said the hackers went unnoticed while they accessed KT's wireless network between Oct. 8. 2024, and Sept. 5, 2025, adding the company only realized the breach had occurred after a user complaint.

It ordered the company to strengthen security measures for its wireless network equipment and its personal information protection measures.

yunhwanchae@yna.co.kr

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