In connection with the unauthorized mobile payment incident at mobile carrier KT, it has been confirmed that the personal information of over 5,500 customers may have been leaked. KT CEO Kim Young-seop issued a public apology and announced follow-up measures to minimize the damage.

Speaking at a press conference held at KT’s Gwanghwamun headquarters in Seoul, Kim said, “We sincerely apologize to the public, our customers, and relevant institutions for the concerns caused. We deeply apologize once again to the customers affected by this incident.” He added, “The company and its employees have devoted all available resources to implement technical measures to prevent further damage, and we will ensure 100 percent compensation for affected customers.”

KT confirmed the personal data leak and reported the matter to the Personal Information Protection Commission. According to KT’s internal investigation, approximately 19,000 customers had received signals from the “unregistered micro base stations” identified as the cause of the incident.

Among them, the subscriber identification information (IMSI) of 5,561 customers was reportedly exposed. IMSI is a unique subscriber identification number stored on a USIM and used to authenticate users on the network. KT notified the affected customers via text messages and phone calls.

However, KT said that no breaches were found in the central server (HSS) where core USIM information is stored, nor were there signs of illegal device modifications or cloned phones. No additional damage has occurred since September 5.

However, KT has not yet provided clear answers regarding how the unregistered micro base stations accessed its network or how the mobile payments were processed.

The company reiterated that it would take responsibility to prevent customer losses, including ensuring that unauthorized payments are not charged to phone bills. So far, 278 customers have been affected, with a total amount of 170 million won, averaging about 540,000 won per person. KT expects that once a full investigation is completed, additional mobile payment victims may number several dozen.

For all users who received signals from the unregistered micro base stations, KT plans to provide free USIM replacements and offer USIM protection services (FDS). Specific compensation measures, including potential fee waivers, will be determined through further discussions and announced at a later date.