Was Lanmark Group hit by ransomware?

Lanmark Group was listed by the sinobi 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 sinobi ransomware group?

sinobi 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 Lanmark Group breach?

sinobi published data attributed to Lanmark Group. Darkfield captured the leak post and a screenshot of the listing.

Ransomware victim disclosure

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Lanmark Group

Claimed by Sinobi · listed 7 months ago

Age

since listed · data leaked

Status timeline

ListedDec 16, 2025
Data leakeddate unknown

At a glance

Group: Sinobi
Status: Data leaked
Country: United States
Listed on leak site: Dec 16, 2025

About the victim

AI dossier — public-source company profile

Lanmark Group, Inc. is a full-service general contracting firm based in Brooklyn, NY, founded in 2005. The company specializes in complex construction projects for both public and private sector clients, including state and municipal agencies. They are known for multi-million dollar construction projects with a focus on quality, safety, and meticulous planning.

Industry: General Contracting & Construction
Address: Brooklyn, NY, United States
Founded: 2005

Attack summary

Severity: high — Data has been published (disclosed status: data_published), indicating confirmed exfiltration. The company works with state and municipal agencies on multi-million dollar projects, meaning leaked data likely includes sensitive government contract information and significant business data.

The ransomware group Sinobi claims an attack on Lanmark Group with a disclosed status of data_published, indicating exfiltration and/or publication of company data. No specific data categories or ransom amount were stated in the post.

high

Data the group says was taken

AI dossier — extracted from the leak post

Business/project records
Government/municipal contract documents
Company financial records

What the group claims

Lanmark Group, Inc. is a full-service general contracting firm based in Brooklyn, NY, founded in 2005. The company specializes in handling complex construction projects for both public and private sector clients, demonstrating a commitment to quality, safety, and client satisfaction. With a focus on meticulous planning and execution, Lanmark has established a strong reputation through their extensive portfolio of successful projects. Their expertise is showcased in multi-million dollar constructions, making them a trusted partner for state and municipal agencies.

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.

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Disclosure context

About sinobi

Based on the limited publicly available information, Sinobi appears to be a recently emerged ransomware operation first observed in July 2025, with financial motivations evidenced by their targeting of 268 victims across multiple sectors. The group's origin and specific affiliations remain undocumented in public threat intelligence reporting, and there is no confirmed information regarding whether they operate as a Ransomware-as-a-Service model or as an independent entity. Their attack methodology and technical capabilities have not been extensively documented by major security research organizations, though their targeting patterns suggest a broad opportunistic approach rather than highly selective operations. The group demonstrates a preference for targeting organizations in the United States, India, United Kingdom, Canada, and Italy, with a focus on manufacturing, healthcare, construction, and technology sectors, suggesting they may exploit common vulnerabilities across these industries rather than deploying sophisticated, sector-specific attack vectors. No major high-profile campaigns or significant law enforcement actions against Sinobi have been publicly reported by CISA, FBI, or established threat intelligence firms. Given the recent emergence timeline and lack of extensive public documentation, the group's current operational status and long-term trajectory remain unclear, though the substantial victim count suggests continued activity as of the last available reporting period. The group has been linked to 274 public disclosures across our corpus. First observed on a leak site on July 5, 2025; most recent post May 8, 2026. The operation is currently active.

Timeline of this disclosure

December 16, 2025Lanmark Group listed by sinobion the group's public leak site

Other recent disclosures by sinobi

sinobi has been linked to 274 public victims on Darkfield. A sample of the most recent:

See the full sinobi dossier →

Sector and geography

Geographically, Lanmark Group is reported in United States, a country with 11,033 ransomware disclosures in our corpus.

If your organisation is affected

A listing by sinobi means Lanmark Group 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 sinobi'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.