SK Telecom Suffers Cyberattack, Exposing USIM Data of 23 Million Customers
SK Telecom, South Korea's largest mobile carrier, confirmed a major cyberattack that exposed sensitive USIM card data belonging to its entire customer base, reportedly over 23 million users. The breach was detected on April 18, 2025, and raised concerns over SIM swapping. While no names or financial details were leaked, technical identifiers like IMSI, MSISDN, and authentication keys were compromised. The company stated it would take full responsibility for any harm caused.
Signal context
First seen: Apr 18, 2025
Last updated: Jun 26, 2026
Status: Public signal
Key points
- Over 23 million customers affected.
- Sensitive USIM card data exposed.
- Breach detected on April 18, 2025.
Signal analysis
BetaThis analysis groups the signal by industry, likely incident action and impacted security area. It helps compare this signal with other published signals without treating the labels as final determinations.
Sector: Information
Likely country: Location not provided
Watch internet-facing systems, credential abuse and exploit activity.
- Source type: outside the affected organization
Impact area: Confidentiality
Likely asset: User or customer data
- 26 signals in the same sector
- 90 signals with the same likely impact area
- 1 signal linked to this organization/domain
External sources
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