INSPECTING ARCHIVED INTELLIGENCE (OUTDATED VERSION).

Yonsei University Hacked, Exposing Student IDs and Contact Information

| 2026-10-23 09:11 HIGH LOW DATA BREACH
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Executive Summary
AI-generated
A cyber attack on Yonsei University's portal service occurred between October 20 and 21, resulting in the leakage of personal information from some employees. The leaked items included student ID numbers, usernames, phone numbers, email addresses, department names, login IP addresses, internal phone numbers, login identification keys, department codes, user IDs, passwords, password error counts, password change dates, user status codes, login dates, and first registration dates. No sensitive information such as resident registration numbers, foreigner registration numbers, or passports was leaked. The incident was reported to the Personal Information Protection Commission, KISA, and the Ministry of Education, with individuals targeted by the breach receiving separate notifications via SMS and email. Yonsei University has established a response hotline for victims and is investigating the matter, while also strengthening its system's security and monitoring for abnormal behavior.
Technical Mitigations AI-generated
• Patch the vulnerability in the portal service's login system, specifically address the irregular method used by the unauthorized external user. • Implement additional security measures to monitor for abnormal behavior and detect potential phishing or account takeover attempts. • Block IP addresses that have been identified as being associated with the breach.
Intelligence Metadata
Actors / Malware / CVEs / Campaigns
Target & Sectors
Global Scope educationeducation
Incident Timeline
‎October 20
Threat actors exploited vulnerabilities between 7:41 pm and October 20, then again from 10:04 am on the same day to Yonsei University, resulting in the leakage of personal information.
general_metric 43 minutes
The incident occurred between 7:41 pm and 43 minutes past 7 pm on October 20, and 10:04 am and 11 minutes past 10 am on October 21.
general_metric 7 pm
The incident occurred between 7:41 pm and 43 minutes past 7 pm on October 20, and 10:04 am and 11 minutes past 10 am on October 21.
general_metric 11 minutes
The incident occurred between 7:41 pm and 43 minutes past 7 pm on October 20, and 10:04 am and 11 minutes past 10 am on October 21.
general_metric 10 am
The incident occurred between 7:41 pm and 43 minutes past 7 pm on October 20, and 10:04 am and 11 minutes past 10 am on October 21.
‎October 21
Threat actors exploited vulnerabilities between 7:41 pm and October 20, then again from 10:04 am on October 21 to 11 minutes past that hour.
general_metric 43 minutes
The incident occurred between 7:41 pm and 43 minutes past 7 pm on October 20, and 10:04 am and 11 minutes past 10 am on October 21.
general_metric 7 pm
The incident occurred between 7:41 pm and 43 minutes past 7 pm on October 20, and 10:04 am and 11 minutes past 10 am on October 21.
general_metric 11 minutes
The incident occurred between 7:41 pm and 43 minutes past 7 pm on October 20, and 10:04 am and 11 minutes past 10 am on October 21.
general_metric 10 am
The incident occurred between 7:41 pm and 43 minutes past 7 pm on October 20, and 10:04 am and 11 minutes past 10 am on October 21.
‎October 22
Threat actors used unauthorized external access to Yonsei University's portal service on October 22, resulting in the leakage of some employees' personal information.
‎October 22nd
Threat actors leaked personal information, including student ID numbers and contact details, from Yonsei University starting at 1 pm on October 22nd.
general_metric 1 pm
Since October 22nd at 1 pm, the university has also started operating a service to check leaked personal information items and a response hotline for victims.
‎2026/10/23
Yonsei University was hacked, resulting in the leakage of personal information, including student ID numbers, contact information, and login IP addresses.
organisation Yonsei University
Yonsei University was hacked, resulting in the leakage of personal information, including student ID numbers, contact information, and login IP addresses..
organisation IP
Yonsei University was hacked, resulting in the leakage of personal information, including student ID numbers, contact information, and login IP addresses..
organisation the Personal Information Protection Commission
The incident was reported to the Personal Information Protection Commission, KISA (Korea Internet & Security Agency), and the Ministry of Education.
organisation KISA
The incident was reported to the Personal Information Protection Commission, KISA (Korea Internet & Security Agency), and the Ministry of Education.
organisation Korea Internet & Security Agency
The incident was reported to the Personal Information Protection Commission, KISA (Korea Internet & Security Agency), and the Ministry of Education.
organisation the Ministry of Education
The incident was reported to the Personal Information Protection Commission, KISA (Korea Internet & Security Agency), and the Ministry of Education.
organisation SMS
Individuals targeted by the breach will receive separate notifications via SMS (LMS) and email.
organisation LMS
Individuals targeted by the breach will receive separate notifications via SMS (LMS) and email.
organisation [email protected]
Yonsei University has established a response hotline for individuals suspected of misuse of their personal information at 02-2123-7015~7017 or via email at [email protected].
organisation Yonsei University's
The personal information leaked items can be confirmed on Yonsei University's official confirmation page.
organisation Information Communication Department
Yonsei University's Information Communication Department has issued an official apology statement, saying, "We will thoroughly investigate the cause of the incident and improve our security system to prevent similar incidents from occurring in the future.
Intelligence Sources
Dailysecu 2026-10-23