Disclosure context

About netrunner

Based on the limited publicly available information, netrunner is a relatively new ransomware group that first emerged in April 2026 with documented attacks against at least six organizations. The group appears to be financially motivated, targeting a diverse range of sectors including healthcare, consumer services, telecommunications, manufacturing, and agriculture across multiple countries including Japan, the United States, Jordan, Italy, and South Korea. Due to the recent emergence of this group and limited public reporting from established threat intelligence sources, detailed information about their country of origin, operational affiliations, specific attack methodologies, encryption techniques, or whether they operate as a Ransomware-as-a-Service model remains undocumented by major cybersecurity organizations such as CISA, FBI, or Mandiant. The group's targeting pattern suggests opportunistic victim selection rather than geopolitically motivated attacks, given the broad geographic and sectoral distribution of their documented victims. No major high-profile campaigns or significant law enforcement actions against netrunner have been publicly reported by reputable security researchers at this time. Given the group's recent emergence in 2026, current activity status and operational capabilities require further monitoring and analysis by the cybersecurity community. The group has been linked to 9 public disclosures across our corpus. First observed on a leak site on April 3, 2026; most recent post May 16, 2026. The operation is currently active.

Timeline of this disclosure

May 15, 2026Shiramume Hospital listed by netrunneron the group's public leak site

Sector and geography

This disclosure adds to ransomware activity in the Healthcare sector, which has 1,779 disclosures indexed across all operators we track. Geographically, Shiramume Hospital is reported in Japan, a country with 108 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

Shiramume Hospital

Claimed by netrunner · listed 6 days ago

Age

since listed · listed for ransom

Status timeline

Listed
May 15, 2026

Current state: Listed for ransom

At a glance

Group: netrunner
Status: Listed for ransom
Country: Japan
Sector: Healthcare
Listed on leak site: May 15, 2026

About the victim

AI dossier — public-source company profile

Shiramume Hospital is a regional general hospital in Japan providing comprehensive inpatient and outpatient care. It offers services in internal medicine, surgery, emergency care, obstetrics/gynecology, and rehabilitation, supported by diagnostic imaging and laboratory facilities. No further details regarding size, founding date, or precise location are available from the leak post or a public site.

Industry: Healthcare — Regional General Hospital

Attack summary

Severity: medium — The victim is a healthcare provider, which inherently involves regulated and sensitive patient data (PII, medical records); however, the post is a bare listing with no confirmed exfiltration, no proof files, no data volume disclosed, and no operational impact described, warranting medium rather than critical.

The netrunner group has listed Shiramume Hospital as a victim; the post does not specify whether data was encrypted, exfiltrated, or both, and no ransom amount or data volume is stated.

medium

What the group claims

A regional general hospital in Japan providing comprehensive inpatient and outpatient care, offering services in internal medicine, surgery, emergency care, obstetrics/gynecology, and rehabilitation, supported by diagnostic imaging and laboratory facilities.

The leak post

captured from the group's site

Seoyon E‑Hwa Summit is a subsidiary of Seoyon E‑Hwa that manufactures automotive components, operating as part of Seoyon E‑Hwa’s international production network. 
GEG srl (est. 1981) designs and builds integrated mobile radio systems across Italy. Over 35 years it served 500+ public administrations and manages 100,000+ radios. Since 2004 it is Italy’s exclusive DAMM TETRA distributor. It held ~60% of the civilian TETRA market (350+ base stations) 
Shiramume Hospital is a regional general hospital in Japan providing comprehensive inpatient and outpatient care. It offers services in internal medicine, surgery, emergency care, obstetrics/gynecology, and rehabilitation, supported by diagnostic imaging and laboratory facilities. 
Nippon Medical School Musashi Kosugi Hospital 
Nippon Medical School Musashi Kosugi Hospital is a 372-bed regional teaching hospital in Nakahara-ku, Kawasaki (Musashi-Kosugi area), affiliated with Nippon Medical School. Established in 1937, it offers comprehensive services across 36 clinical departments, including emergency and critical care, ICU, NICU, perinatal and pediatric care, cancer treatment, and minimally invasive endovascular procedures. The hospital…

Screenshot of the leak post

Sources

Leak posthttp://netrunrsb3bivj5gnwajzxlig5qkteb6edgthxj7fmsvhkzxtwfxwaad.onion

Source

Indexed 6 days 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.