Incident Score: Analysis & Impact (SUB1770295740)
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Rankiteo Score Impact Analysis
Key Highlights From The Incident Analysis
- Timeline of Substack'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 Substack 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 Substack breach identified under incident ID SUB1770295740.
The analysis begins with a detailed overview of Substack's information like the linkedin page: https://www.linkedin.com/company/substack, the number of followers: 72365, the industry type: Online Audio and Video Media and the number of employees: 2843 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 715 and after the incident was 660 with a difference of -55 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 Substack and their customers.
On 03 February 2025, Substack disclosed Data Breach issues under the banner "Substack 2025 Data Breach Exposing User Email Addresses and Phone Numbers".
Substack has notified select users that their email addresses and phone numbers were exposed in a security incident last October.
The disruption is felt across the environment, and exposing Email addresses, phone numbers, internal metadata.
In response, moved swiftly to contain the threat with measures like Patched the vulnerability, and began remediation that includes Strengthening security measures, and stakeholders are being briefed through Email notification to affected users.
The case underscores how Ongoing, with advisories going out to stakeholders covering Email notification sent to affected users.
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 Exploit Public-Facing Application (T1190) with moderate confidence (60%), with evidence including unauthorized third party accessed internal data, and patched the vulnerability and Trusted Relationship (T1199) with lower confidence (40%), supported by evidence indicating internal data accessed, no details on root cause. Under the Credential Access tactic, the analysis identified Unsecured Credentials (T1552) with moderate confidence (50%), supported by evidence indicating internal metadata exposed, no evidence of misuse. Under the Collection tactic, the analysis identified Data from Local System (T1005) with moderate to high confidence (80%), supported by evidence indicating email addresses, phone numbers, internal metadata compromised. Under the Exfiltration tactic, the analysis identified Exfiltration Over C2 Channel (T1041) with moderate to high confidence (70%), supported by evidence indicating unauthorized third party accessed internal data and Transfer Data to Cloud Account (T1537) with moderate confidence (50%), supported by evidence indicating no details on data exfiltration method. Under the Impact tactic, the analysis identified Data Destruction (T1485) with lower confidence (20%), supported by evidence indicating no evidence the data has been misused. These correlations help security teams understand the attack chain and develop appropriate defensive measures based on the observed tactics and techniques.
Sources & References
- Substack Rankiteo Cyber Incident Details: https://www.rankiteo.com/company/substack/incident/SUB1770295740
- Substack CyberSecurity Rating page: https://www.rankiteo.com/company/substack
- Substack Rankiteo Cyber Incident Blog Article: https://blog.rankiteo.com/sub1770295740-substack-breach-february-2026/
- Substack CyberSecurity Score History: https://www.rankiteo.com/company/substack/history
- Substack CyberSecurity Incident Source: https://www.theverge.com/tech/874255/substack-data-breach-user-emails-phone-numbers
- 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