Was Multistack hit by ransomware?

Multistack was listed by the Blackbyte ransomware operation (United States), 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 Blackbyte ransomware group?

Blackbyte 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 Multistack breach?

Blackbyte published data attributed to Multistack. Darkfield captured the leak post and a screenshot of the listing.

Ransomware victim disclosure

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Multistack

Claimed by Blackbyte · listed 3 years ago

37m

Age

since listed · data leaked

Status timeline

ListedJun 16, 2023
Data leakeddate unknown

At a glance

Group: Blackbyte
Status: Data leaked
Country: United States
Sector: Manufacturing
Listed on leak site: Jun 16, 2023

About the victim

AI dossier — public-source company profile

Multistack is a U.S.-based manufacturer of eco-friendly modular HVAC chiller systems, including air-cooled, water-cooled, and MagLev (magnetic levitation) platforms. The company specializes in energy-efficient, scalable, and environmentally responsible cooling and heating solutions for commercial and industrial buildings. Multistack distributes its products globally across regions including North America, Europe, Africa, Australia, and Asia.

Industry: HVAC Equipment Manufacturing (Modular Chillers)

Attack summary

Severity: high — Data has been confirmed published by BlackByte (disclosed status: data_published), indicating successful exfiltration. Even without explicit enumeration of data types, a confirmed data publication event from a known ransomware group targeting a manufacturing company constitutes a high-severity incident.

BlackByte claims to have compromised Multistack and has published data from the attack. The disclosed status indicates data has been published, suggesting exfiltration of company data, though the specific data categories and volume were not explicitly enumerated in the leak post.

high

Data the group says was taken

AI dossier — extracted from the leak post

Company internal data
Potentially proprietary engineering/product designs
Business operations data

What the group claims

At Multistack, we recognize and respect the importance of providing HVAC solutions that promote energy and water efficiency, utilize the best refrigerant choices available, and embrace the transition from fossil fuels to electrification.Water and air-cooled MagLev® chiller platforms achieve superb efficiency across their full range of operation. Our unique MagLev chiller design and unrivalled Transitional Efficiency? chiller control algorithms deliver outstanding part-load performance at all condenser-water or ambient temperature conditions. MagLev also offers refrigerant choices recognized worldwide safer for the environment: R1234ze, R-513, and R515B.Our modular product’s design allows you the freedom to use just enough energy to meet your current needs, while offering you the flexibility of incorporating additional modules as your operations grow. Minimizing embodied energy is an important design focus and we pride ourselves that our modular chillers deliver the industry’s highest cooling and heating output per pound. If you’re looking to cool and heat your building with as little environmental impact as possible, look no further than Multistack!

Sources

Victim sitemultistack.com

Source

Indexed 3 years 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 Blackbyte

BlackByte is a ransomware-as-a-service (RaaS) operation that emerged in October 2021, primarily motivated by financial gain through double extortion tactics targeting organizations across multiple sectors. The group is suspected to operate from Russia or former Soviet states based on their use of Russian-language forums and avoidance of targeting organizations in Commonwealth of Independent States countries, though they maintain no confirmed links to other established ransomware families. BlackByte operators typically gain initial access through vulnerable Microsoft Exchange servers, phishing campaigns, and exploitation of remote desktop protocol (RDP) services, employing tools such as Cobalt Strike for lateral movement and data exfiltration before deploying their custom ransomware payload that uses AES-256 encryption with RSA-2048 key protection. The group has demonstrated particular focus on critical infrastructure sectors, with the FBI and CISA issuing joint advisories in February 2022 highlighting attacks against organizations in government, healthcare, manufacturing, and education sectors, including notable incidents affecting San Francisco's transportation authority and multiple healthcare systems across the United States. BlackByte remains active as of 2024, continuing to evolve their tactics and maintain their leak site for publishing stolen data from victims who refuse to pay ransoms. The group has been linked to 147 public disclosures across our corpus. First observed on a leak site on October 4, 2021; most recent post July 30, 2025. The operation is currently inactive.

Timeline of this disclosure

June 16, 2023Multistack listed by Blackbyteon the group's public leak site

Other recent disclosures by Blackbyte

Blackbyte has been linked to 147 public victims on Darkfield. A sample of the most recent:

See the full Blackbyte dossier →

Sector and geography

This disclosure adds to ransomware activity in the Manufacturing sector, which has 3,681 disclosures indexed across all operators we track. Geographically, Multistack is reported in United States, a country with 11,033 ransomware disclosures in our corpus.

If your organisation is affected

A listing by Blackbyte means Multistack 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, CISA (United States), as required for your jurisdiction.
Monitor for the data appearing on Blackbyte'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.