SK Telecom Says Malware Incident Leaked Customer USIM Data

South Korean telecom giant SK Telecom has disclosed a security incident involving a malware infection that may have led to the unauthorized exposure of customer USIM-related data on April 19.

Although no misuse of the compromised data has been observed so far, the company has taken immediate containment and mitigation steps and notified the appropriate regulatory bodies.

SK Telecom, the largest mobile carrier in South Korea with over 29 million mobile subscribers, plays a pivotal role in the country’s telecommunications infrastructure. As a subsidiary of SK Group, one of Korea’s largest conglomerates, the company provides nationwide 5G, LTE, and AI-powered services and is a critical part of the country’s digital economy.

According to a press release issued by SK Telecom earlier today, the incident occurred late in the evening on April 19, when internal monitoring systems detected unusual activity linked to malware infiltration. Preliminary investigations point to a potential leak of USIM (Universal Subscriber Identity Module) information. In response, SK Telecom deleted the malware and quarantined the affected systems to prevent further compromise. The firm reported the breach to the Korea Internet & Security Agency (KISA) the following day and later to the Personal Information Protection Commission (PIPC), pledging full cooperation with ongoing investigations.

The company clarified that while the full scope and nature of the breach are still under investigation, there is currently no evidence that the leaked data has been exploited. However, to prevent potential abuse, SK Telecom has reinforced its defenses against unauthorized SIM card swaps and abnormal identity verification attempts. It is also conducting a full audit of its systems and implementing stricter protocols to detect and block suspicious activity in real time.

Additionally, SK Telecom is offering a free USIM Protection Service to concerned customers via its website and mobile platform, T World. This service aims to add another layer of security against SIM-related fraud or identity theft by monitoring and limiting changes related to USIM cards.

The company says it is enhancing its security architecture to prevent future breaches and developing more comprehensive safeguards for customer information. SK Telecom also apologized to its users for the incident and encouraged affected individuals to contact its customer service hotline for further assistance.