Disclosure context

About J

The J ransomware group is a newly emerged threat actor first observed in May 2025, operating with apparent financial motivations based on their targeting patterns across multiple countries and sectors. With limited public documentation available from established security research organizations, the group has demonstrated rapid operational capability by compromising 41 known victims within their initial months of activity. Their targeting strategy appears opportunistic, focusing primarily on organizations in the United States, United Kingdom, France, Argentina, and Germany, with a particular emphasis on technology companies, manufacturing firms, construction businesses, and business services providers. The diversity of their geographic and sectoral targeting suggests either a broad-spectrum approach to victim selection or potential use of automated tools for initial compromise identification. Given the recent emergence of this group and limited reporting from major cybersecurity firms and law enforcement agencies, specific details regarding their technical methodologies, ransom demands, data exfiltration practices, or organizational structure remain undocumented in publicly available threat intelligence. The group remains active as of current reporting periods, though their relative obscurity in established threat intelligence databases suggests they may be operating at a smaller scale compared to more prominent ransomware-as-a-service operations. The group has been linked to 41 public disclosures across our corpus. First observed on a leak site on May 2, 2025; most recent post November 9, 2025. The operation is currently inactive.

Timeline of this disclosure

August 20, 2025southweststone.net listed by Jon the group's public leak site

Sector and geography

This disclosure adds to ransomware activity in the Construction sector, which has 415 disclosures indexed across all operators we track. Geographically, southweststone.net is reported in United States, a country with 7,392 ransomware disclosures in our corpus.

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.

Ransomware victim disclosure

← All victims

Southwest Stone

listed as southweststone.net · Claimed by J · listed 9 months ago

Age

since listed · data leaked

Status timeline

Listed
Aug 20, 2025
Data leaked

At a glance

Group: J
Status: Data leaked
Country: United States
Sector: Construction
Listed on leak site: Aug 20, 2025

About the victim

AI dossier — public-source company profile

Southwest Stone is a premier natural stone quarrier established in 2001, operating multiple quarries throughout Utah and Idaho. The company supplies natural stone products including veneer, landscape stone, architectural stone, and wall cap/coping materials. It serves construction and landscaping markets with an experienced staff spanning management, sales, and production.

Industry: Natural Stone Quarrying & Supply
Address: Utah & Idaho, United States (multiple quarry locations; no single street address stated)
Founded: 2001

Attack summary

Severity: medium — Data has been published (confirmed exfiltration and release), but no specific sensitive data categories (PII at scale, financial, medical) are identified, and the company is a small regional stone quarrier with limited known regulatory data exposure.

The ransomware group 'J' claims to have published data obtained from Southwest Stone; the disclosed status is 'data_published', indicating exfiltration and release of company data. No specific data categories or ransom amount were stated in the leak post.

medium

Data the group says was taken

AI dossier — extracted from the leak post

Company data (unspecified)

Original description

AI-summarised, not from the leak post

N/A

Sources

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.