Incident Score: Analysis & Impact (KT1785198533)
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Rankiteo Score Impact Analysis
Key Highlights From The Incident Analysis
- Timeline of KT's Breach and lateral movement inside company's environment.
- Overview of affected data sets, including SSNs and PHI, and why they materially increase incident severity.
- How Rankiteo’s incident engine converts technical details into a normalized incident score.
- How this cyber incident impacts KT Rankiteo cyber scoring and cyber rating.
- Rankiteo’s MITRE ATT&CK correlation analysis for this incident, with associated confidence level.
Full Incident Analysis Transcript
In this Rankiteo incident briefing, we review the KT breach identified under incident ID KT1785198533.
The analysis begins with a detailed overview of KT's information like the linkedin page: https://www.linkedin.com/company/kt, the number of followers: 21774, the industry type: Telecommunications and the number of employees: 8326 employees
After the initial compromise, the video explains how Rankiteo's incident engine converts technical details into a normalized incident score. The incident score before the incident was 767 and after the incident was 581 with a difference of -186 which is could be a good indicator of the severity and impact of the incident.
In the next step of the video, we will analyze in more details the incident and the impact it had on KT and their customers.
KT Corp. recently reported "KT Corp. Data Breach via Illegal Femtocell Attack", a noteworthy cybersecurity incident.
South Korea’s Personal Information Protection Commission (PIPC) investigated a 2023 data breach at KT Corp.
The disruption is felt across the environment, and exposing Personal data of 22,227 subscribers, with nearly 22,227 records at risk, plus an estimated financial loss of 243000000 KRW (~180000 USD).
Formal response steps have not been shared publicly yet.
The case underscores how Ongoing (PIPC plenary meeting on July 29).
Finally, we try to match the incident with the MITRE ATT&CK framework to see if there is any correlation between the incident and the MITRE ATT&CK framework.
The MITRE ATT&CK framework is a knowledge base of techniques and sub-techniques that are used to describe the tactics and procedures of cyber adversaries. It is a powerful tool for understanding the threat landscape and for developing effective defense strategies.
MITRE ATT&CK® Correlation Analysis
Rankiteo's analysis has identified several MITRE ATT&CK tactics and techniques associated with this incident, each with varying levels of confidence based on available evidence. Under the Initial Access tactic, the analysis identified Network Sniffing (T1465) with high confidence (90%), with evidence including illegal small-cell base station (femtocell) attack, and exposed IMSI numbers, IMEI numbers, and phone numbers. Under the Credential Access tactic, the analysis identified Adversary-in-the-Middle (T1557) with high confidence (90%), with evidence including illegal femtocell attack intercepted subscriber data, and unauthorized micropayment transactions and Modify Authentication Process (T1556) with moderate to high confidence (70%), supported by evidence indicating unauthorized micropayment transactions totaling 243 million won. Under the Collection tactic, the analysis identified Data from Information Repositories (T1213) with moderate to high confidence (80%), supported by evidence indicating exposed personal data of 22,227 subscribers (IMSI, IMEI, phone numbers). Under the Exfiltration tactic, the analysis identified Exfiltration Over C2 Channel (T1041) with moderate to high confidence (80%), with evidence including data breach exposed 22,227 subscriber lines, and unauthorized micropayments. Under the Impact tactic, the analysis identified Resource Hijacking (T1496) with moderate to high confidence (80%), supported by evidence indicating unauthorized micropayment transactions totaling 243 million won and Account Access Removal (T1531) with moderate confidence (60%), supported by evidence indicating potential reputational damage due to regulatory scrutiny. Under the Defense Evasion tactic, the analysis identified Modify Cloud Compute Infrastructure (T1578) with moderate to high confidence (70%), supported by evidence indicating illegal femtocell attack bypassed standard network safeguards. These correlations help security teams understand the attack chain and develop appropriate defensive measures based on the observed tactics and techniques.
Sources & References
- KT Rankiteo Cyber Incident Details: https://www.rankiteo.com/company/kt/incident/KT1785198533
- KT CyberSecurity Rating page: https://www.rankiteo.com/company/kt
- KT Rankiteo Cyber Incident Blog Article: https://blog.rankiteo.com/kt1785198533-kt-corp-breach-september-2025/
- KT CyberSecurity Score History: https://www.rankiteo.com/company/kt/history
- KT CyberSecurity Incident Source: https://www.thelec.net/news/articleView.html?idxno=12560
- Rankiteo A.I CyberSecurity Rating methodology: https://www.rankiteo.com/Images/rankiteo_algo.pdf
- Rankiteo TPRM Scoring methodology: https://static.rankiteo.com/model/rankiteo_tprm_methodology.pdf