Was O'Shea Builders hit by ransomware?

O'Shea Builders was listed by the Medusa ransomware operation (United States), and stolen data was published on the group's leak site. Darkfield tracks this disclosure with the original leak post, screenshot and group context.

Who is the Medusa ransomware group?

Medusa is a ransomware operator tracked by Darkfield. See the full operator dossier for its known victims, sectors targeted, IOCs and leak-site infrastructure.

What data was leaked in the O'Shea Builders breach?

Medusa published data attributed to O'Shea Builders (~120.50 GB), around 137 employees records. Darkfield captured the leak post and a screenshot of the listing.

Ransomware victim disclosure

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O'Shea Builders

Claimed by Medusa · listed 1 year ago

120.50 GB

Data size

137 employees records

15m

Age

since listed · data leaked

Status timeline

ListedMar 29, 2025
Data leakeddate unknown

At a glance

Group: Medusa
Status: Data leaked
Country: United States
Sector: Construction
Listed on leak site: Mar 29, 2025
Data size: 120.50 GB
Records: 137 employees

About the victim

AI dossier — public-source company profile

O'Shea Builders is a commercial construction-services provider founded in 1902, headquartered in Springfield, Illinois with additional offices in Decatur and Peoria. The company specializes in general contracting, construction management, design-build, civil engineering, and building maintenance services across Central Illinois.

Industry: Commercial Construction Services
Address: 3401 Constitution Dr, Springfield, Illinois 62711, United States
Employees: 137
Founded: 1902

Attack summary

Severity: high — Confirmed exfiltration and publication of 120.50 GB of data from an established business. Likely includes employee PII, client contracts, and operational/financial data; no encryption mentioned but data is already public, indicating maximum damage has occurred.

Medusa claims to have exfiltrated 120.50 GB of data from O'Shea Builders. The group has published the data; no ransom demand is stated, indicating a pure extortion or reputational attack.

high

Data the group says was taken

AI dossier — extracted from the leak post

Corporate records
Employee information
Client project data
Financial documents
Operational files

What the group claims

O'Shea Builders (founded in 1902) is a commercial construction-services provider in Illinois with offices in Springfield and Peoria. O'Shea Builders provide general contracting, construction management, design build, civil and building maintenance services. O'Shea Builders corporate office is located in 3401 Constitution Dr, Springfield, Illinois, 62711, United States and has 137 employees. The total amount of data leakage is 120.50 GB

Sources

Source

Indexed 1 year ago

This page surfaces a public ransomware disclosure indexed by Darkfield. Original posts come from the operator's own leak site; we cross-check against ransomware.live, RansomLook and RansomWatch where applicable. Share this URL freely.

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Disclosure context

About Medusa

Medusa, also known as MedusaLocker, is a financially motivated ransomware group that emerged in November 2022 and has since compromised 568 known victims across multiple countries. The group's origin and specific affiliations remain unclear from publicly available intelligence, though their operational patterns suggest they function as an independent ransomware operation rather than a documented Ransomware-as-a-Service model. Medusa primarily targets organizations in the United States, United Kingdom, Canada, Italy, and Australia, with a focus on business services, healthcare, manufacturing, and technology sectors, employing typical ransomware tactics including data encryption and likely exfiltration for double extortion purposes, though specific technical methodologies and initial access vectors have not been extensively documented in public threat intelligence reports. While the group has maintained a relatively high victim count since its emergence, detailed information about specific notable campaigns, high-profile victims, or major ransom demands has not been widely reported by major cybersecurity firms or law enforcement agencies. As of current intelligence assessments, Medusa appears to remain active in the threat landscape, continuing to target organizations across their established geographic and sectoral preferences. The group has been linked to 635 public disclosures across our corpus. First observed on a leak site on November 15, 2022; most recent post May 5, 2026. The operation is currently active.

Also tracked as: MedusaLocker, MEDUSA LOCKER.

Timeline of this disclosure

March 29, 2025O'Shea Builders listed by Medusaon the group's public leak site

Data size: 120.50 GB
Records: 137 employees

Other recent disclosures by Medusa

Medusa has been linked to 635 public victims on Darkfield. A sample of the most recent:

See the full Medusa dossier →

Sector and geography

This disclosure adds to ransomware activity in the Construction sector, which has 988 disclosures indexed across all operators we track. Geographically, O'Shea Builders is reported in United States, a country with 11,033 ransomware disclosures in our corpus.

If your organisation is affected

A listing by Medusa means O'Shea Builders appeared on a ransomware extortion site and data attributed to it has been published. If this is your organisation, or a supplier you depend on, the priority is to confirm the intrusion and contain it before the window to act closes.

Engage your incident-response team and preserve forensic evidence before remediating — do not wipe affected systems first.
Force a password reset and revoke active sessions for exposed accounts; rotate any credentials, API keys or certificates that may have been in the stolen data.
Assess regulatory notification duties (GDPR, NIS2, sector regulators) — many carry a 72-hour reporting clock from awareness.
Report the incident to your national CERT, CISA (United States), as required for your jurisdiction.
Monitor for the data appearing on Medusa's leak site and across paste and breach channels, and brief downstream partners who may be exposed through you.

How we know this. Darkfield monitors public ransomware leak sites continuously, archiving every new disclosure and the data later released against the victim. Each entry on this page is sourced from the operator's own publication and cross-checked against complementary OSINT feeds (RansomLook, ransomware.live, RansomWatch). We do not collect or host stolen data — only the metadata, timestamps and screenshots needed to make the public disclosure searchable and accountable. Records here are corrected when the original post is edited, retracted, or merged with another disclosure.