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Yulkok Ltd

Claimed by Beast · listed 5 months ago

5m
Age
since listed · data leaked

Status timeline

  1. ListedFeb 5, 2026
  2. Data leakeddate unknown

At a glance

Group
Beast
Status
Data leaked
Country
South Korea
Listed on leak site
Feb 5, 2026

About the victim

AI dossier — public-source company profile

Yulkok Ltd. is a South Korean aerospace manufacturer headquartered in Changwon, founded in 1990. The company specialises in high-precision 5-axis CNC metal machining and fuselage component assembly for the aerospace industry. It supplies components to major global customers including Boeing, Airbus, and Korea Aerospace Industries (KAI), including for military aircraft such as the T-50 and FA-50.

Industry
Aerospace & Defence Manufacturing
Address
Changwon, South Korea
Founded
1990

Attack summary

Severity: critical — Yulkok Ltd. is an aerospace and defence manufacturer producing components for military aircraft (T-50, FA-50) in partnership with Boeing, Airbus, and KAI. Data published from such a firm is highly likely to include sensitive defence-related technical data, manufacturing specifications, and potentially export-controlled information, placing this in the critical category.

The BEAST ransomware group claims to have attacked Yulkok Ltd. and has published data ('data_published' status), though the leak post does not specify whether encryption, exfiltration, or both occurred, nor the volume of data involved.

critical

Data the group says was taken

AI dossier — extracted from the leak post
  • Aerospace manufacturing data
  • Defence component specifications
  • Partner/supplier information

What the group claims

Yulkok Ltd. (South Korea) This is a major global player with the same name. Operations: Manufacturing high-precision parts and assemblies for the aerospace industry. Specialization: 5-axis CNC metal machining, fuselage component assembly. Partners: Collaborates with global giants such as Boeing and Airbus, as well as Korea Aerospace Industries (KAI) for the production of military aircraft (e.g., T-50, FA-50). Location: Headquartered in Changwon, South Korea; founded in 1990.

The leak post

captured from the group's site
AJU Pharm Co., Ltd. is a prominent South Korean total healthcare company founded in 1953. For over 70 years, it has evolved from a manufacturer of raw materials into a global pharmaceutical group specializing in prescription drugs, medical devices, and health supplements
P U B L I S H E D

Sources

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 beast

The Beast ransomware group is a relatively new threat actor that emerged in July 2025, operating with apparent financial motivations through their ransomware campaigns. With limited public documentation available from major security agencies, the group has demonstrated activity primarily targeting victims across the United States, United Kingdom, Brazil, South Korea, and Argentina, accumulating approximately 65 known victims since their emergence. Their targeting pattern shows a focus on healthcare organizations, manufacturing companies, educational institutions, and construction firms, suggesting an opportunistic approach rather than highly specialized sector expertise. The group's recent emergence means there is insufficient public intelligence from CISA, FBI, Mandiant, or other established security researchers regarding their specific attack methodologies, initial access vectors, or technical capabilities. Given the timeline of their first observation in mid-2025, Beast represents an active and emerging threat with their current operational status remaining unclear due to limited threat intelligence reporting from authoritative sources. The group has been linked to 104 public disclosures across our corpus. First observed on a leak site on July 29, 2025; most recent post June 11, 2026. The operation is currently active.

Timeline of this disclosure

  • February 5, 2026Yulkok Ltd listed by beaston the group's public leak site

Other recent disclosures by beast

beast has been linked to 104 public victims on Darkfield. A sample of the most recent:

See the full beast dossier →

Sector and geography

Geographically, Yulkok Ltd is reported in South Korea, a country with 48 ransomware disclosures in our corpus.

If your organisation is affected

A listing by beast means Yulkok Ltd 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, KrCERT/CC (South Korea), as required for your jurisdiction.
  • Monitor for the data appearing on beast'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.