South Korea’s largest cell operator, SK Telecom, is warning {that a} malware an infection allowed menace actors to entry delicate USIM-related info for purchasers.
SK Telecom is the biggest cell community operator in South Korea, holding roughly 48.4% of the cell phone service market within the nation, akin 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 turned conscious of the doable leak, we instantly deleted the malware and remoted the gear suspected of being hacked,” reads the safety discover.
“As of now, there have been no confirmed instances of the leaked info 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 as we speak.
Investigations are underway, and the compromise’s actual trigger, scale, or scope has not but been decided.
USIM information is info saved on a Common Subscriber Identification Module (USIM), which sometimes contains Worldwide Cellular Subscriber Identification (IMSI), Cellular Station ISDN Quantity (MSISDN), authentication keys, community utilization information, and SMS or contacts if saved on the SIM.
This information could possibly be used for focused surveillance, monitoring, and SIM-swap assaults.
Whereas SK Telecom says there isn’t a 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 join USIM safety service by means of this portal, which blocks cell numbers from being ported to a different SIM card when enabled.
On the time of writing, no menace actors have taken duty for the assault at SK Telecom.
