SKT’s delayed response to hacking incident fuels consumer anxiety

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SKT’s delayed response to hacking incident fuels consumer anxiety

Published: 28 Apr. 2025, 00:00

Audio report: written by reporters, read by AI

A notice informing customers of a shortage of USIM chips is posted at an SK Telecom store in Seoul on April 27. Starting April 28, SK Telecom plans to offer free replacement of USIM and eSIM chips to all subscribers. [YONHAP]

SK Telecom, Korea’s largest mobile carrier, will offer free replacement USIM chips to all 23 million of its subscribers starting Monday, following a cyberattack that resulted in the leakage of USIM information. However, the measure comes 10 days after the company first detected the incident. Amid concerns regarding an expected shortage of replacement chips, a chaotic rush for exchanges seems inevitable, meaning consumer anxiety and confusion will likely persist for some time.

The USIM stores personal identification and authentication data essential for accessing mobile networks. If USIM data is cloned, malicious actors could intercept text messages, calls, financial authentication processes and even change account passwords. Although the probability is not high, there remains the possibility that cloned phones could be used to access banking or securities apps to steal money, leaving subscribers understandably alarmed.

Nevertheless, SKT’s response to the incident has been deeply flawed. On the night of April 18, the company’s home subscriber server (HSS) was infected with malware, raising concerns about a potential leak of sensitive information such as mobile subscriber identification numbers, international mobile equipment identity (IMEI) numbers and USIM authentication keys. Yet SKT waited three days before disclosing the breach to the public on April 21. It also reported the incident to the relevant authorities more than 24 hours after detection, a clear violation of the expected reporting timeline. Subscriber notifications were equally inadequate. Text alerts providing details of the breach and instructions for enrolling in SKT’s “USIM Protection Service” to prevent further damage were only sent on Wednesday. Only after mounting consumer anger and anxiety did SKT announce, on Friday — an entire week after detecting the breach — that it would offer free USIM replacements to all subscribers.

SK Telecom CEO Ryu Young-sang, center, bows during a public apology session at the company’s headquarters in Jung District, central Seoul, on April 25. [NEWS1]

SKT has claimed that no resident registration numbers or other personal information were compromised and that no secondary damage from misuse of USIM data has been identified. Yet the company still cannot confirm the full extent of the breach, including the volume and scope of the leaked information. Thus, it cannot definitively rule out the possibility of additional damage. Most concerning is the fact that the HSS, a core part of its infrastructure managing integrated data on USIM information and service plans, was hacked. As a highly secured central server, its compromise is a shocking development.

In modern life, mobile phones are not merely communication tools — they function as digital IDs and platforms for authentication in online financial transactions and other critical services. The potential fallout from a hacking incident at a telecommunications company is therefore enormous. In response to the USIM breach, acting President Han Duck-soo ordered a thorough analysis of the cause of the attack and instructed authorities to transparently inform the public while rigorously inspecting and improving cybersecurity systems across government agencies.

SKT must also conduct a full investigation into the cause of the breach and swiftly implement measures to reinforce security and prevent future incidents. Furthermore, it must spare no effort to minimize damage and ease the anxieties and inconveniences of consumers, particularly the elderly and other digitally vulnerable groups.

Translated from the JoongAng Ilbo using generative AI and edited by Korea JoongAng Daily staff.