Was Otto Sieve GmbH hit by ransomware?

Otto Sieve GmbH was listed by the Storm ransomware operation (Germany), and stolen data was published on the group's leak site. Darkfield tracks this disclosure with the original leak post, screenshot and group context.

Who is the Storm ransomware group?

Storm is a ransomware operator tracked by Darkfield. See the full operator dossier for its known victims, sectors targeted, IOCs and leak-site infrastructure.

What data was leaked in the Otto Sieve GmbH breach?

Storm published data attributed to Otto Sieve GmbH. Darkfield captured the leak post and a screenshot of the listing.

Ransomware victim disclosure

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Otto Sieve GmbH

Claimed by Storm · listed 3 hours ago

Today

Age

since listed · data leaked

Status timeline

ListedAug 27, 2026
Data leakeddate unknown

At a glance

Group: Storm
Status: Data leaked
Country: Germany
Sector: Manufacturing
Listed on leak site: Aug 27, 2026

About the victim

AI dossier — public-source company profile

Otto Sieve GmbH is a family-owned German company founded in 1967, headquartered in Lohne, Lower Saxony. It specializes in building services including heating, ventilation, sanitary systems, solar technology, and renewable energy solutions for new construction, renovation, and maintenance projects.

Industry: Building Services & HVAC Systems
Address: Lindenstraße 102a, 49393 Lohne, Germany
Employees: 11-50
Founded: 1967

Attack summary

Severity: low — No proof files, screenshots, or data samples are advertised. No data types are disclosed. No operational impact is stated. The post is announcement only.

The ransomware group claims to have compromised Otto Sieve GmbH. The leak post does not specify the nature of the compromise (encryption, exfiltration, or both) or detail what data is at stake.

low

What the group claims

Otto Sieve GmbH is a family-owned German company specializing in building services and modern home technology. Founded in 1967, the company provides heating, ventilation, sanitary, solar, and renewable energy solutions. Its services cover the planning, installation, maintenance, repair, and modernization of heating systems, bathrooms, heat pumps, solar technology, ventilation, and related building systems. Otto Sieve serves customers involved in new construction, renovation, and modernization projects and also provides maintenance and emergency repair services. The company emphasizes energy-efficient, sustainable solutions, technical expertise, personal consultation, and high-quality workmanship. Its headquarters is in Lohne, Lower Saxony, Germany. The company headquarters is located in LindenstraÃŸe 102a, 49393 Lohne, Germany. 11-50 Employees

Sources

Leak posthttp://yqhecvqtdvq6p7duqcgw2qca77spbgakxcoibtx6zpvfshltsbbbhfqd.onion/company/6a8c10d7bcb899d105729a16

Source

Indexed 3 hours 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 Storm

Storm is a ransomware group first observed in August 2026, operating with an apparent financial motivation based on its targeting profile, though limited public documentation exists given its recent emergence and relatively small victim footprint. The group has claimed or been attributed to attacks against at least six known victims, with the United States representing its primary target geography. Storm has demonstrated a preference for targeting the healthcare and manufacturing sectors, alongside a broader category of other industries, suggesting an opportunistic rather than highly specialized targeting philosophy. Due to the group's recent emergence and limited victim count, comprehensive technical details regarding its initial access vectors, encryption methodology, tooling, or affiliation with known threat actor ecosystems have not yet been formally documented by CISA, the FBI, Mandiant, or other major threat intelligence publishers as of the time of this writing. No confirmed RaaS infrastructure, dark web leak site activity, or law enforcement actions against the group have been publicly attributed or reported in open sources. Given its nascent operational timeline beginning in 2026, Storm should be monitored as an emerging threat, particularly within the healthcare sector where ransomware attacks carry significant operational and patient safety implications, but analysts should treat any further characterization beyond the known victim and targeting data with caution pending additional corroborating intelligence. The group has been linked to 41 public disclosures across our corpus. First observed on a leak site on August 7, 2026; most recent post August 27, 2026. The operation is currently active.

Timeline of this disclosure

August 27, 2026Otto Sieve GmbH listed by Stormon the group's public leak site

Other recent disclosures by Storm

Storm has been linked to 41 public victims on Darkfield. A sample of the most recent:

See the full Storm dossier →

Sector and geography

This disclosure adds to ransomware activity in the Manufacturing sector, which has 3,692 disclosures indexed across all operators we track. Geographically, Otto Sieve GmbH is reported in Germany, a country with 383 ransomware disclosures in our corpus.

If your organisation is affected

A listing by Storm means Otto Sieve GmbH 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, CERT-Bund (Germany), as required for your jurisdiction.
Monitor for the data appearing on Storm'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.