Disclosure context

About killsec

killsec is a relatively new ransomware group that emerged in March 2024, operating with apparent financial motivations and demonstrating broad targeting across multiple geographic regions and industry sectors. The group's origin and potential state affiliations remain unclear due to limited public documentation from major threat intelligence sources, though their targeting pattern suggests opportunistic rather than geopolitically motivated operations. With 276 documented victims primarily concentrated in the United States, India, the United Kingdom, Brazil, and Belgium, killsec appears to focus heavily on healthcare, technology, business services, and financial sectors, indicating either specific tooling designed for these environments or opportunistic targeting of organizations with valuable data and high pressure to restore operations quickly. Given the group's recent emergence and the lack of detailed technical analysis from established cybersecurity firms like Mandiant or law enforcement advisories from CISA or FBI, specific details about their attack methodology, initial access vectors, encryption techniques, and extortion tactics have not been publicly documented in authoritative sources. The group remains active as of current reporting, though the limited intelligence profile suggests they may be either a smaller operation or one that has not yet attracted significant attention from major threat intelligence organizations despite their substantial victim count. The group has been linked to 279 public disclosures across our corpus. First observed on a leak site on March 21, 2024; most recent post May 14, 2026. The operation is currently active.

Timeline of this disclosure

May 1, 2026Medical PAY listed by killsecon the group's public leak site

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, Medical PAY is reported in JP, a country with 88 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

Medical PAY

Claimed by killsec · listed 20 days ago

19d

Age

since listed · data leaked

Status timeline

Listed
May 1, 2026
Data leaked

At a glance

Group: killsec
Status: Data leaked
Country: JP
Sector: Financial Services
Listed on leak site: May 1, 2026

About the victim

AI dossier — public-source company profile

Medical PAY (medical-pay.jp) is a Japan-based company operating in the financial services sector with a focus on medical payment processing. Based on its name and domain, it likely provides payment solutions or billing services to medical institutions or patients in Japan. No additional public site content was available to confirm further operational details.

Industry: Medical Payment Processing & Financial Services

Attack summary

Severity: high — The victim operates in medical payment processing in Japan, meaning any exfiltrated data likely involves financial and potentially health-related PII. The 'data_published' status indicates confirmed data disclosure rather than a mere listing, elevating severity despite the lack of explicit detail in the post.

KillSec claims to have attacked Medical PAY and has published data (disclosed status: data_published), though the leak post provides minimal detail on whether encryption or exfiltration occurred and does not specify the volume or nature of the data involved.

high

What the group claims

Price ??? Disclosures 0/1

Sources

Victim sitemedical-pay.jp

Source

Indexed 20 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.