Lanmark Group Listed by sinobi Ransomware Group

On December 16, 2025, construction contractor Lanmark Group appeared on the leak site of the sinobi ransomware group. The Brooklyn-based firm, which handles multimillion-dollar public and private projects, is claimed to have had internal files exfiltrated after a ransomware attack. While the exact number of people whose information was taken remains unknown, anyone whose personal or employment records passed through the company could be affected.

Reported Details from Reporting

Public reporting indicates that sinobi claims to have stolen internal documents from Lanmark Group during a ransomware operation. The data consists of internal files rather than a structured database of customer records. The listing appeared on the group’s onion site on December 16, 2025. No specific volume of records or list of exposed data types such as Social Security numbers has been publicly detailed yet. The company, founded in 2005, specializes in complex construction projects for state, municipal, and private clients across the New York region.

Why This Matters for You and Your Family

When a company that manages large contracts and government work is breached, the information inside its files often includes details about employees, subcontractors, vendors, and sometimes clients. If your name, address, date of birth, tax documents, or contact information ever appeared in Lanmark’s systems, those records could now be in attackers’ hands. For families, this means your information and potentially your children’s information may surface in unexpected places. Construction firms routinely handle insurance forms, background checks, and payment records that contain exactly the data needed for identity theft or targeted scams.

The Doxxing and Identity-Chain Risks

Stolen internal files frequently contain more than names and addresses. They can include email accounts, phone numbers, project notes, and references to family members or dependents. Attackers stitch these fragments together into an identity chain that links your work history to personal accounts, social-media handles, and even children’s gaming usernames. Once the chain exists, a single leaked credential can lead to account takeovers across email, banking, and gaming platforms. Credential leaks like this one regularly cascade into doxxing campaigns where private family details are published or used for harassment and extortion.

Sinobi Ransomware Group’s Known Activity

Public reporting attributes the attack to the sinobi ransomware group. The group emerged in recent years and has targeted organizations across multiple sectors by deploying ransomware, exfiltrating data, and then publishing samples on its leak site to pressure victims into payment. Their typical playbook involves initial access through common vulnerabilities or phishing, followed by data theft and extortion demands that escalate if the target does not pay. Notable prior victims have included companies in manufacturing, services, and local-government contracting, though details remain limited in open sources.

What to do

• Run a DoxxScan to map every link between your emails, phone numbers, handles, and real-world identity so you can see exactly what chains back to the Lanmark breach.
• Rotate any password you used at Lanmark Group or any related vendor account, then enable 2FA through an authenticator app rather than text messages.
• Enable continuous DoxxScan monitoring across 13.1B+ breach records and 100+ platforms so the next time your information appears it is caught within hours instead of months.
• Cover the entire household with DoxxScan family protection that extends to dependents and children’s gaming accounts, which often become targets when parent credentials surface in leaks like this.
• Let remediation specialists handle takedown requests and broker removals for you while you focus on securing accounts and watching for suspicious activity.

The Lanmark Group incident shows how quickly contractor data can become public ammunition for ransomware operators. Taking concrete steps now limits how far attackers can travel down the identity chain that begins with this claimed breach. DoxxScan by GalaxyWarden delivers continuous monitoring across 13.1 billion+ breach records and more than 100 platforms, AI-powered identity-chain mapping, hands-on remediation by specialists, and full household coverage that includes children’s gaming accounts. Start your DoxxScan trial today to gain clear visibility and expert help before the next wave of misuse begins.