SK Telecom offers free SIM replacements following cyberattack

SK Telecom has introduced free SIM card replacements for its 25 million customers due to the USIM data breach earlier this month. However, only 6 million replacements will be available until May 2025.

On April 19, the company identified malware on its network that enabled attackers to access customers’ Universal Subscriber Identity Module (USIM) data.

This database may include information such as International Mobile Subscriber Identity, Mobile Station ISDN Number, network usage details, authentication keys, and stored SMS or contacts.

In addition, the company insisted that no customer names, identification details, or financial information were compromised in this incident.

The primary concern arising from this breach is the risk of unauthorised number porting to cloned SIM cards, commonly called SIM swapping.

 

SK Telecom assures the public they have already placed countermeasures to prevent potential risks.

 

In an update released earlier this week, SK Telecom reassured customers that its Fraud Detection System (FDS) and SIM Protection Service have been upgraded to address this heightened risk. The system aims to identify and stop fraudulent requests automatically.

The telecommunication firm is providing free SIM card replacements to all 25 million subscribers, including about 2 million using budget carriers, who might be vulnerable to SIM swapping attacks.

However, the mobile provider cautions that due to limited inventory, it can only replace 6 million SIM cards by May 2025. Currently, the company possesses 1 million SIM cards and intends to acquire an additional 5 million by the end of May 2025, as stated in the update.

Furthermore, the potential traffic congestion should urge customers to utilise the online reservation platform to arrange their SIM replacement ahead of time. Only customers who were subscribed as of April 18, 2025, at midnight (Japan time) are eligible for the SIM replacement.

Meanwhile, the company has released an FAQ page regarding the cybersecurity breach, indicating ongoing investigations into its causes and implications. As of now, there has been no confirmation of secondary damage or leaks on the dark web.

All affected customers will receive a personalised message containing security instructions.