[Second Report] KT: "USIM Info of 5,561 Users Leaked... Reported to Personal Information Protection Commission"

Guidance provided to victims on applying for USIM replacement and enrolling in USIM protection services

(Seoul=Yonhap News) Reporter Cho Seong-mi = KT [030200] announced on the 11th that it has confirmed the potential leakage of personal information belonging to 5,561 users through illegal micro-base stations—the suspected cause of unauthorized micropayments—and has reported the incident to the Personal Information Protection Commission.

KT stated that its internal investigation uncovered circumstances indicating that the International Mobile Subscriber Identity (IMSI) of some users was compromised via illegal micro-base stations.

IMSI is a unique number assigned to each subscriber and constitutes personal information stored on the USIM card.

It was determined that among users with a history of receiving signals from illegal micro-base stations, 5,561 individuals were identified as having a potential IMSI leak.

This afternoon, KT sent SMS messages to the affected users, informing them of the report filed with the Personal Information Protection Commission, how to check for potential damage, and providing links to apply for USIM replacement and enroll in protection services.

KT plans to provide free USIM replacements and offer USIM protection services to all users who have a history of receiving signals from illegal micro-base stations.

Mounting KT Micropayment Damages (Seoul=Yonhap News) Reporter Lee Jin-wook = According to the Gyeonggi Nambu Provincial Police Agency's Cyber Investigation Unit on the 10th, there have been a total of 124 reported cases of KT micropayment fraud between the 27th of last month and 6:00 PM on the 9th, with total damages estimated at approximately 80.6 million KRW. It is highly suspected that hackers intercepted users' normal traffic through micro-base stations to commit the fraud; as there is a possibility that the illegal base stations were mounted on vehicles and moved during the crime, the scope and scale of the damage could increase further. The photo shows a small KT mobile communication device installed at a Seoul subway station on the 10th. 2025.9.10 cityboy@yna.co.kr