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SK Telecom registers more than 24 million users in USIM Protection Service after data breach

Published: 06 May. 2025, 13:17 Updated: 06 May. 2025, 15:14

A notice at a SK Telecom branch in Seoul says the store has run out of SIM cards on April 28, the same day the carrier started a replacement service for all subscribers following a data breach. [YONHAP]

SK Telecom said Tuesday it has enrolled more than 24 million customers on its USIM Protection Service following a recent data breach involving the company's network.

Some 24.1 million subscribers had been signed in to the service as of 9 a.m., the company said in a daily briefing on its response to the hacking incident.

About 1.04 million users also switched their SIM cards after the company began offering free replacements to all of its customers last week, with an accumulated 7.8 million having made reservations.

The automatic enrollment system began Friday to provide the same level of defense against illegal financial activities as physically replacing the SIM.

“We apologize as many of our users are still waiting to replace their USIM cards,” said Kim Hee-sup, head of SK Telecom's Public Relations Center, noting the company is working to resolve the shortage “as soon as possible.”

SK Telecom, the largest mobile carrier in Korea, detected a cyberattack on April 18 and discovered signs of a large-scale leak of customers' SIM data.

The company's user base accounts for nearly half the country's population of some 52 million.

On Monday, SK Telecom suspended new subscriber sign-ups nationwide in compliance with the government's administrative guidance not to receive new customers until it resolves the ongoing shortage of SIM cards for replacement and stronger measures are implemented to protect customer data.

Yonhap