Skip to main content
Darkfield

Ransomware victim disclosure

← All victims

Käslin SA

listed as Ernest Käslin · Claimed by Worldleaks · listed 7 months ago

7m
Age
since listed · data leaked

Status timeline

  1. ListedDec 8, 2025
  2. Data leakeddate unknown

At a glance

Group
Worldleaks
Status
Data leaked
Country
Switzerland
Listed on leak site
Dec 8, 2025

About the victim

AI dossier — public-source company profile

Käslin SA is a Swiss building services company headquartered in Corcelles, canton of Neuchâtel, operating since 1960 across three generations. The firm specialises in sanitary installations, heating systems, roofing, and energy solutions, offering 24/7 emergency services. It operates as a group of complementary companies under one roof to serve diverse and demanding client requirements.

Industry
Building Services & Technical Installation (Plumbing, Heating, Roofing, Energy)
Address
Place de la Gare 3, CH-2035 Corcelles, Switzerland
Founded
1960

Attack summary

Severity: medium — Data is listed as published, indicating confirmed exfiltration; however, no details on data volume, regulated data (PII, financial, medical), or operational disruption are stated, and the leak post content is not available. The company is a small regional building services firm, limiting likely scale of sensitive data.

The worldleaks group claims to have published data belonging to Käslin SA, with the disclosed status listed as data_published, indicating exfiltration and release of company data. No specific data categories or volume are described in the truncated leak post.

medium

Data the group says was taken

AI dossier — extracted from the leak post
  • Company internal data (type unspecified)

Original description

AI-summarised, not from the leak post

N/A

Sources

Source

Indexed 7 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.

Is this your supplier? Your competitor? You?

Pro plans monitor your domain, corporate emails, and crypto wallets across every new ransomware leak-site post, breach dump and Telegram callout — alerts within 5 minutes.

Disclosure context

About worldleaks

Based on the limited available data, worldleaks is a recently emerged ransomware group that was first observed in May 2025 and appears to be primarily financially motivated, having claimed 134 victims in a relatively short timeframe since its emergence. The group's origin and organizational structure remain unclear, with no publicly documented information from major cybersecurity firms or law enforcement agencies regarding their country of origin, potential affiliations, or operational model. Their targeting patterns indicate a focus on English-speaking countries, particularly the United States, United Kingdom, and Canada, with additional activity observed in Germany and Japan, while their sector targeting shows a preference for healthcare, technology, manufacturing, and consumer services organizations. Due to the group's recent emergence and limited public documentation by established threat intelligence sources, specific details about their attack methodologies, encryption techniques, extortion tactics, and notable campaigns have not yet been comprehensively analyzed or reported by organizations such as CISA, FBI, or major cybersecurity research firms. The group appears to remain active as of the most recent observations, though comprehensive threat intelligence profiling awaits further analysis and documentation by established cybersecurity authorities. The group has been linked to 173 public disclosures across our corpus. First observed on a leak site on May 18, 2025; most recent post July 2, 2026. The operation is currently active.

Timeline of this disclosure

  • December 8, 2025Ernest Käslin listed by worldleakson the group's public leak site

Other recent disclosures by worldleaks

worldleaks has been linked to 173 public victims on Darkfield. A sample of the most recent:

See the full worldleaks dossier →

Sector and geography

Geographically, Ernest Käslin is reported in Switzerland, a country with 154 ransomware disclosures in our corpus.

If your organisation is affected

A listing by worldleaks means Ernest Käslin 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, NCSC-CH (Switzerland), as required for your jurisdiction.
  • Monitor for the data appearing on worldleaks'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.