Was Sternthal Montigny Greenberg St-Germain hit by ransomware?

Sternthal Montigny Greenberg St-Germain was listed by the brotherhood ransomware operation (Canada), 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 brotherhood ransomware group?

brotherhood 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 Sternthal Montigny Greenberg St-Germain breach?

brotherhood published data attributed to Sternthal Montigny Greenberg St-Germain (~22 GB). Darkfield captured the leak post and a screenshot of the listing.

Ransomware victim disclosure

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Sternthal Montigny Greenberg St-Germain LLP

listed as Sternthal Montigny Greenberg St-Germain · Claimed by Brotherhood · listed 9 months ago

22 GB

Data size

Age

since listed · data leaked

Status timeline

ListedOct 10, 2025
Data leakeddate unknown

At a glance

Group: Brotherhood
Status: Data leaked
Country: Canada
Listed on leak site: Oct 10, 2025
Data size: 22 GB

About the victim

AI dossier — public-source company profile

Sternthal Montigny Greenberg St-Germain LLP (SMGS) is a Montreal-based law firm with over 45 years of operation, offering personalized legal services in business and commercial law, personal legal matters, litigation and dispute resolution, and banking, financing and insolvency. The firm is led by a team of named partners and associates reachable at their Place du Canada office. They serve both business and individual clients primarily in the province of Québec.

Industry: Legal Services
Address: Place du Canada, 1010 de la Gauchetière West, Suite 200, Montréal, Québec, H3B 2N2, Canada
Employees: 1-10

Attack summary

Severity: critical — SMGS is a law firm whose files are inherently likely to contain privileged legal communications, client PII, financial records, and potentially sensitive litigation materials. A 22 GB exfiltration from a legal practice with disclosed/published status constitutes a critical exposure of regulated and highly sensitive data at scale.

The Brotherhood ransomware group claims to have exfiltrated 22 GB of compressed files from SMGS and has published the data. No ransom amount was stated and no details on encryption were provided.

critical

Data the group says was taken

AI dossier — extracted from the leak post

Compressed files (22 GB)

What the group claims

Contains: 22 Gb compressed Files

Sources

Victim sitewww.smgs.ca
Leak posthttp://brohoodyaifh2ptccph5zfljyajjabwjjo4lg6gfp4xb6ynw5w7ml6id.onion/

Source

Indexed 9 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 brotherhood

The Brotherhood ransomware group is a recently emerged financially-motivated cybercriminal organization first observed in October 2025, representing one of the newer entrants in the ransomware landscape. Given the group's recent emergence and limited public documentation from major security firms and law enforcement agencies, detailed information about their origin, country of operation, and specific affiliations remains largely unknown to open-source intelligence. Based on observed targeting patterns, the group appears to employ opportunistic attack methodologies, focusing primarily on English-speaking markets including the United States, Australia, and Canada, while also targeting victims in Germany and Switzerland, suggesting either broad-spectrum initial access capabilities or acquisition of access through underground markets. Their victim selection spans multiple sectors including business services, construction, transportation and logistics, and technology companies, indicating a non-discriminatory approach typical of many financially-motivated ransomware operations rather than targeted campaigns against specific industries. With only 18 documented victims since their October 2025 emergence, Brotherhood represents a relatively small-scale operation compared to established ransomware groups, and specific details regarding their encryption methods, data exfiltration practices, or extortion tactics have not been publicly documented by major threat intelligence providers. The group remains active as of the latest available intelligence, though their limited operational footprint and recent emergence means comprehensive analysis of their tactics, techniques, and procedures awaits further documentation by security researchers and law enforcement agencies. The group has been linked to 18 public disclosures across our corpus. First observed on a leak site on October 10, 2025; most recent post January 6, 2026. The operation is currently active.

Timeline of this disclosure

October 10, 2025Sternthal Montigny Greenberg St-Germain listed by brotherhoodon the group's public leak site

Data size: 22 GB

Other recent disclosures by brotherhood

brotherhood has been linked to 18 public victims on Darkfield. A sample of the most recent:

See the full brotherhood dossier →

Sector and geography

Geographically, Sternthal Montigny Greenberg St-Germain is reported in Canada, a country with 1,055 ransomware disclosures in our corpus.

If your organisation is affected

A listing by brotherhood means Sternthal Montigny Greenberg St-Germain 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, CCCS (Canada), as required for your jurisdiction.
Monitor for the data appearing on brotherhood'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.