South Korea’s largest cellular operator, SK Telecom, is warning {that a} malware an infection allowed risk actors to entry delicate USIM-related data for patrons.
SK Telecom is the biggest cellular community operator in South Korea, holding roughly 48.4% of the cell phone service market within the nation, equivalent to 34 million subscribers.
The corporate says they detected malware on their methods at 11 PM native time on Saturday, April 19, 2025, in a weekend cyberattack when most organizations are understaffed.
“As soon as we grew to become conscious of the attainable leak, we instantly deleted the malware and remoted the tools suspected of being hacked,” reads the security discover.
“As of now, there have been no confirmed circumstances of the leaked data being misused.”
The breach was reported to the Korea Web & Safety Company (KISA) the next day, and the nation’s Private Data Safety Fee was notified earlier at present.
Investigations are underway, and the compromise’s actual trigger, scale, or scope has not but been decided.
USIM information is data saved on a Common Subscriber Id Module (USIM), which sometimes consists of Worldwide Cell Subscriber Id (IMSI), Cell Station ISDN Quantity (MSISDN), authentication keys, community utilization information, and SMS or contacts if saved on the SIM.
This information might be used for focused surveillance, monitoring, and SIM-swap assaults.
Whereas SK Telecom says there isn’t any proof that the leaked information has been abused, the corporate has strengthened blocks of USIM swaps and irregular authentication makes an attempt and can instantly droop service for accounts linked to suspicious exercise.
Subscribers are beneficial to enroll in USIM safety service by this portal, which blocks cellular numbers from being ported to a different SIM card when enabled.
On the time of writing, no risk actors have taken duty for the assault at SK Telecom.
