Mountain West Bank Breach Incident Score: Analysis & Impact (MOU1766434320)

In this Rankiteo incident briefing, we review the Mountain West Bank breach identified under incident ID MOU1766434320.

The analysis begins with a detailed overview of Mountain West Bank's information like the linkedin page: https://www.linkedin.com/company/mountain-west-bank, the number of followers: 2991, the industry type: Financial Services and the number of employees: 513 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 757 and after the incident was 688 with a difference of -69 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 Mountain West Bank and their customers.

On 18 December 2025, Mountain West disclosed Data Breach issues under the banner "Mountain West Data Breach".

Mountain West reported that sensitive personal identifiable information in its care may have been compromised.

The disruption is felt across the environment, and exposing Sensitive personal identifiable information.

In response, and stakeholders are being briefed through Data breach notification letters mailed to impacted individuals.

The case underscores how and recommending next steps like 24 months of complimentary credit monitoring services for affected individuals, with advisories going out to stakeholders covering Data breach notification letters sent to impacted individuals with details of exposed information.

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.

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 Valid Accounts (T1078) with moderate to high confidence (70%), supported by evidence indicating sensitive PII (names, SSNs) compromised; likely account abuse and Exploit Public-Facing Application (T1190) with moderate confidence (50%), supported by evidence indicating financial services org; no attack vector details disclosed. Under the Credential Access tactic, the analysis identified Modify Authentication Process (T1556) with moderate confidence (60%), supported by evidence indicating high-risk PII exposure implies possible auth bypass. Under the Exfiltration tactic, the analysis identified Exfiltration Over C2 Channel (T1041) with moderate to high confidence (80%), supported by evidence indicating sSNs and names exposed; likely exfiltrated and Automated Exfiltration (T1020) with moderate confidence (60%), supported by evidence indicating large-scale PII breach suggests automated methods. Under the Impact tactic, the analysis identified Data Encrypted for Impact (T1486) with lower confidence (40%), supported by evidence indicating no ransomware details, but PII exposure may imply encryption and Data Manipulation: Stored Data Manipulation (T1565.001) with lower confidence (30%), supported by evidence indicating pII compromise could involve unauthorized modifications. These correlations help security teams understand the attack chain and develop appropriate defensive measures based on the observed tactics and techniques.