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Analyze » Hallisey & D'Agostino, LLP » HDL1776537263

Incident Score: Analysis & Impact (HDL1776537263)

The details regarding individual company incidents & reports gives you full view from every side.

Rankiteo Score Impact Analysis

Rankiteo Incident Impact-82
Company Score Before Incident751 / 1000
Company Score After Incident669 / 1000
Company LinkView Hallisey & D'Agostino, LLP Profile
INCIDENT NUMBERHDL1776537263
Type of Cyber IncidentBreach
ATTACK VECTORNA
DATA EXPOSEDSensitive personal information
INCIDENT DATE27/09/2025
STATUSCompleted

Key Highlights From The Incident Analysis

  • Timeline of Hallisey & D'Agostino, LLP'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 Hallisey & D'Agostino, LLP 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 Hallisey & D'Agostino, LLP breach identified under incident ID HDL1776537263.

The analysis begins with a detailed overview of Hallisey & D'Agostino, LLP's information like the linkedin page: https://www.linkedin.com/company/hdllp, the number of followers: 142, the industry type: Accounting and the number of employees: 17 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 751 and after the incident was 669 with a difference of -82 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 Hallisey & D'Agostino, LLP and their customers.

On 17 April 2026, Hallisey & D’Agostino, LLP disclosed Data Breach issues under the banner "Hallisey & D’Agostino, LLP Data Breach Exposes Personal Information of Over 16,000 Individuals".

Hallisey & D’Agostino, LLP, a Connecticut-based public accounting firm, recently disclosed a data breach that compromised the sensitive personal information of 16,683 individuals across the U.S., including 74 in Maine.

The disruption is felt across the environment, and exposing Sensitive personal information, with nearly 16683 records at risk.

In response, and stakeholders are being briefed through Written notices to affected individuals.

The case underscores how Completed, with advisories going out to stakeholders covering Written notices sent to affected individuals.

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 Valid Accounts (T1078) with moderate confidence (60%), supported by evidence indicating unauthorized actor accessed the firm’s systems between September 28 and October 22, 2025 and Exploit Public-Facing Application (T1190) with lower confidence (40%), supported by evidence indicating detected unusual activity in its network on October 21, 2025. Under the Persistence tactic, the analysis identified Valid Accounts (T1078) with moderate confidence (50%), supported by evidence indicating accessed the firm’s systems over a 24-day period (September 28 - October 22, 2025). Under the Credential Access tactic, the analysis identified Unsecured Credentials (T1552) with moderate confidence (50%), supported by evidence indicating sensitive personal information of 16,683 individuals compromised. Under the Collection tactic, the analysis identified Data from Local System (T1005) with moderate to high confidence (80%), supported by evidence indicating files containing personal data potentially exfiltrated. Under the Exfiltration tactic, the analysis identified Exfiltration Over C2 Channel (T1041) with moderate to high confidence (70%), supported by evidence indicating potentially exfiltrating files containing personal data. Under the Impact tactic, the analysis identified Data Manipulation: Transmitted Data Manipulation (T1565.002) with lower confidence (40%), supported by evidence indicating sensitive personal information of 16,683 individuals compromised. These correlations help security teams understand the attack chain and develop appropriate defensive measures based on the observed tactics and techniques.

Initial Access
Valid Accounts (60%)
Exploit Public-Facing Application (40%)
Persistence
Valid Accounts (50%)
Credential Access
Unsecured Credentials (50%)
Collection
Data from Local System (80%)
Exfiltration
Exfiltration Over C2 Channel (70%)
Impact
Data Manipulation: Transmitted Data Manipulation (40%)

Sources & References