Was JLK Rosenberger hit by ransomware?

JLK Rosenberger was listed by the INC Ransom 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 INC Ransom ransomware group?

INC Ransom 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 JLK Rosenberger breach?

INC Ransom published data attributed to JLK Rosenberger (~300 GB). Darkfield captured the leak post and a screenshot of the listing.

Ransomware victim disclosure

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JLK Rosenberger LLP

listed as JLK Rosenberger · Claimed by INC Ransom · listed 5 months ago

300 GB

Data size

Age

since listed · data leaked

Status timeline

ListedJan 28, 2026
Data leakeddate unknown

At a glance

Group: INC Ransom
Status: Data leaked
Country: United States
Sector: Financial Services
Listed on leak site: Jan 28, 2026
Data size: 300 GB

About the victim

AI dossier — public-source company profile

JLK Rosenberger LLP is a full-service accounting and business advisory firm with offices in Irvine and Glendale, California, and Dallas, Texas. The firm is recognized as a Top 400 accounting firm by Inside Public Accounting and is one of the largest auditors of insurance entities in the United States as ranked by Aon and AM Best.

Industry: Certified Public Accounting & Business Advisory
Address: Offices in Irvine, CA; Glendale, CA; and Dallas, TX, United States

Attack summary

Severity: critical — The firm is a large CPA and insurance auditor handling sensitive financial and client data at scale; 300 GB of exfiltrated data encompassing internal mail, accounting records, and customer information almost certainly includes regulated financial PII and confidential client financial records, meeting the threshold for critical severity.

INC Ransom claims to have exfiltrated 300 GB of data from JLK Rosenberger LLP, including internal mail, accounting records, and customer information, and has threatened to publish all data imminently.

critical

Data the group says was taken

AI dossier — extracted from the leak post

Internal email communications
Accounting records
Customer information

What the group claims

JLK Rosenberger LLP, Certified Public Accountants: A full service accounting and business advisory firm with offices in Irvine and Glendale, California and Dallas, Texas. The firm is recognized as a Top 400 Firm by Inside Public Accounting and one of the largest auditors of insurance entities in the United States as ranked by Aon and AM Best We have 300GB of data. Internal mail, accounting, company customer information and we will publish all the information next week.

Source

Indexed 5 months 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 INC Ransom

INC Ransom is a financially motivated ransomware group that emerged in September 2021 and has since compromised 832 known victims across multiple sectors. The group's origin and specific affiliations remain undocumented in public threat intelligence reports, though their operational patterns suggest they likely operate as an independent entity rather than a formal Ransomware-as-a-Service model. While detailed attack methodologies for INC Ransom have not been extensively documented by major security firms, their victim distribution indicates they employ broad-spectrum targeting approaches that have successfully penetrated healthcare, technology, business services, and manufacturing organizations. The group demonstrates a preference for targeting English-speaking countries, with the United States, Canada, and United Kingdom representing their primary victim demographics, alongside significant activity in Germany and Australia. Notable campaigns or high-profile attacks by INC Ransom have not been prominently featured in major threat intelligence publications from CISA, FBI, or leading security researchers, suggesting they may operate with a lower public profile despite their substantial victim count. INC Ransom remains active as of current intelligence assessments, with no documented law enforcement disruptions or confirmed rebranding efforts. The group has been linked to 853 public disclosures across our corpus. First observed on a leak site on September 9, 2021; most recent post June 6, 2026. The operation is currently active.

Also tracked as: INC.

Timeline of this disclosure

January 28, 2026JLK Rosenberger listed by INC Ransomon the group's public leak site

Data size: 300 GB

Other recent disclosures by INC Ransom

INC Ransom has been linked to 853 public victims on Darkfield. A sample of the most recent:

See the full INC Ransom dossier →

Sector and geography

This disclosure adds to ransomware activity in the Financial Services sector, which has 516 disclosures indexed across all operators we track. Geographically, JLK Rosenberger is reported in United States, a country with 7,392 ransomware disclosures in our corpus.

If your organisation is affected

A listing by INC Ransom means JLK Rosenberger 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.
Monitor for the data appearing on INC Ransom'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.