All 3 Korean Carriers Hacked in 2025: What You Must Do Now

In 2025, all three of South Korea's major telecom carriers were hacked. The most severe incident: SKT's USIM data of 23.24 million subscribers was leaked, resulting in a record 134.8 billion KRW fine.

Breach Timeline by Carrier

Carrier	Incident	Impact	Penalty
SKT	USIM data breach (April)	23.24M subscribers	134.8B KRW fine
KT	Femtocell (illegal micro base station) attack	74 victims, 240M KRW financial damage	Under investigation
LGU+	Server hack, customer data exposed	Scale under investigation	PIPC investigation

What Was Leaked

• IMSI (International Mobile Subscriber Identity): Unique SIM identifier
• IMEI (International Mobile Equipment Identity): Device identifier
• Phone numbers: Subscriber contact information
• Subscriber info: Names, dates of birth, basic personal data

Risks from Leaked Data

Risk Type	Description
SIM swapping	Cloning SIM using leaked data to intercept verification codes
Identity theft	Opening new phone lines or loans under victim's name
Targeted phishing	Precision phishing using leaked personal information
Financial fraud	Intercepting OTPs for unauthorized transactions

5 Actions You Must Take Immediately

1. Enroll in USIM Protection Service (Free)

All 3 carriers now offer free USIM protection post-breach.

Carrier	How to Enroll
SKT	T World app > Additional Services > USIM Protection
KT	My KT app > Security Service
LGU+	Your U+ app > Security Settings

2. Set Up PASS App Notifications

• Enable identity verification alerts in the PASS app
• Get instant notification when someone attempts authentication under your name

3. Block Non-Face-to-Face Activation

• Through carrier app or customer service, enable non-face-to-face activation block
• Prevents anyone from reissuing a SIM under your name remotely

4. Monitor Financial Accounts

• Enable transfer notifications on all banking apps
• Check login history for securities, insurance, and other financial accounts
• Contact your bank immediately if you notice suspicious activity

5. Change All Passwords

• Change carrier account passwords
• Change email passwords (email is the password reset hub)
• Change financial app passwords
• Enable two-factor authentication (2FA) on every service possible

Government Response

• Personal Information Protection Commission (PIPC): Investigating all 3 carriers
• Ministry of Science and ICT: Formed telecom security task force
• SKT fine: Record-breaking 134.8 billion KRW penalty

Storing Telecom Account Info Securely

Storing carrier account information, security settings, and passwords in regular note apps or messaging yourself on iMessage creates security vulnerabilities.

With LOCK.PUB's encrypted memo feature:

• Store carrier account info encrypted and secure
• Keep USIM protection enrollment confirmations
• Record password change history in password-protected memos
• Set expiration times so information is accessible only when needed

When sharing security procedures with family, LOCK.PUB's password-protected links keep the information safe.

Final Thoughts

Carrier hacking isn't your fault, but post-breach response is your responsibility. Execute the 5 actions above right now, and share this guide with family. Especially help elderly family members enroll in USIM protection services and set up non-face-to-face activation blocks.

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Related Agencies: PIPC | Ministry of Science and ICT | FSS 1332