In response to the incident, SK Group chair Chey Tae-won publicly apologized, acknowledging the anxiety caused to customers and committing to cooperate with government investigators.

Additionally, the company is blocking illegal SIM card changes and abnormal authentication attempts, while offering a free 'SIM protection service' to customers.

The malware was detected on April 19, 2025, prompting SK Telecom to notify the Korea Internet & Security Agency (KISA) the following day.

To enhance security, SK Telecom has implemented stricter protocols for SIM management, actively monitoring accounts for suspicious activity to prevent further breaches.

The company's breach notification indicated that some SIM-related information was suspected to have been leaked, although investigations are ongoing to ascertain the extent and specifics of the data compromised.

SK Telecom, South Korea's largest telecom provider with around 34 million subscribers, recently reported a data breach involving customer Universal Subscriber Identity Module (USIM) information due to a malware attack.

As part of its security measures, SK Telecom has halted new subscriber registrations and is replacing existing customers' SIM cards for free, leading to shortages at retail outlets.

Looking ahead, SK Group plans to review its security systems, increase investments in security, and establish an Information Protection Innovation committee with external experts to prevent future incidents.

USIM cards are critical for user authentication, storing sensitive data such as IMSI numbers and encryption keys; unauthorized access could enable cybercriminals to conduct surveillance and SIM-swapping attacks.

In the broader context of digital security, solutions like those offered by SSOJet, including secure single sign-on services and multi-factor authentication, are essential for enterprises to strengthen their defenses.