(LEAD) KT fined 54 bln won over data leak via illegal base stations

Yonhap reported that the breach affected phone numbers and mobile device identification numbers belonging to 16,647 users. The attackers reportedly built illegal base stations using authentication certificates extracted from base stations KT had lost, allowing them to access the wireless network. The watchdog said the intrusion went unnoticed from Oct. 8, 2024, to Sept. 5, 2025, and KT only realized the breach after a user complaint. The regulator ordered KT to strengthen its security measures and also said it would file a police complaint over a separate hacking incident the company did not report.