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Cyber Threat
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Ransomware victim Public Sector

Instituut voor de Nederlandse

Listed by Thegentlemen on · organisation based in Netherlands

ivdnt.org

Disclosed
May 15, 2026
Leak-site listing date
Threat group
Thegentlemen
1,081 victims listed
Country
Netherlands
#22 most targeted
Sector
Public Sector

ThreatAI analysis

Compiled from this incident record and the threat intelligence profile for Thegentlemen. Figures and technique mappings are quoted from the source data, not inferred.

About the Thegentlemen group

The Gentlemen is a RaaS group that emerged in July–August 2025, rapidly claiming over 320 victims across 17+ countries by offering affiliates a 90% revenue share, deploying a Go-based locker against Windows, Linux, NAS, and BSD systems; a compromised C2 server in 2026 revealed more than 1,570 linked victims. Thegentlemen has listed 922 victims since February 2023.

How Thegentlemen is documented to operate

Valid Accounts T1078 Stealth Persistence

Adversaries may obtain and abuse credentials of existing accounts as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Compromised credentials may be used to bypass access controls placed on various resources on systems within the network and may even be used for persistent access to remote systems and externally available services, such as VPNs, Outlook Web Access, network devices, and remote desktop. Compromised credentials may also grant an adversary increased privilege to specific systems or access to restricted areas of the network.

Mitigations: Application Developer Guidance, User Training, Password Policies, User Account Management, Privileged Account Management, Multi-factor Authentication

MITRE ATT&CK reference
External Remote Services T1133 Persistence Initial Access

Adversaries may leverage external-facing remote services to initially access and/or persist within a network. Remote services such as VPNs, Citrix, and other access mechanisms allow users to connect to internal enterprise network resources from external locations. There are often remote service gateways that manage connections and credential authentication for these services. Services such as Windows Remote Management and VNC can also be used externally. Access to Valid Accounts to use the service is often a requirement, which could be obtained through credential pharming or by obtaining the credentials from users after compromising the enterprise network.

Mitigations: Limit Access to Resource Over Network, Restrict Web-Based Content, Network Segmentation, Multi-factor Authentication, Disable or Remove Feature or Program

MITRE ATT&CK reference
Exploit Public-Facing Application T1190 Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network. The weakness in the system can be a software bug, a temporary glitch, or a misconfiguration. Exploited applications are often websites/web servers, but can also include databases (like SQL), standard services (like SMB or SSH), network device administration and management protocols (like SNMP and Smart Install), and any other system with Internet-accessible open sockets. On ESXi infrastructure, adversaries may exploit exposed OpenSLP services; they may alternatively exploit exposed VMware vCenter servers.

Mitigations: Vulnerability Scanning, Limit Access to Resource Over Network, Filter Network Traffic, Network Segmentation, Privileged Account Management, Application Isolation and Sandboxing

MITRE ATT&CK reference
Phishing T1566 Initial Access

Adversaries may send phishing messages to gain access to victim systems. All forms of phishing are electronically delivered social engineering. Phishing can be targeted, known as spearphishing. In spearphishing, a specific individual, company, or industry will be targeted by the adversary. More generally, adversaries can conduct non-targeted phishing, such as in mass malware spam campaigns. Adversaries may send victims emails containing malicious attachments or links, typically to execute malicious code on victim systems. Phishing may also be conducted via third-party services, like social media platforms.

Mitigations: Network Intrusion Prevention, Restrict Web-Based Content, User Training, Antivirus/Antimalware, Software Configuration, Audit

MITRE ATT&CK reference
Windows Management Instrumentation T1047 Execution

Adversaries may abuse Windows Management Instrumentation (WMI) to execute malicious commands and payloads. WMI is designed for programmers and is the infrastructure for management data and operations on Windows systems. WMI is an administration feature that provides a uniform environment to access Windows system components. The WMI service enables both local and remote access, though the latter is facilitated by Remote Services such as Distributed Component Object Model and Windows Remote Management. Remote WMI over DCOM operates using port 135, whereas WMI over WinRM operates over port 5985 when using HTTP and 5986 for HTTPS.

Mitigations: Execution Prevention, Behavior Prevention on Endpoint, User Account Management, Privileged Account Management

MITRE ATT&CK reference

MITRE ATT&CK techniques attributed to Thegentlemen across its recorded activity, not a finding about how Instituut voor de Nederlandse was reached.

Vulnerabilities Thegentlemen is recorded exploiting

6 of these 6 are in the CISA Known Exploited Vulnerabilities catalog, 4 of them recorded by CISA as used in ransomware campaigns. CVEs attributed to Thegentlemen across its reported activity. There is no indication that any of these was involved in the Instituut voor de Nederlandse incident — the source data does not record an entry point.

Incident analysis

Instituut voor de Nederlandse was listed by Thegentlemen ransomware, a group with 1,081 victims recorded in this database. The listing appeared on the group's leak site on May 15, 2026.

Instituut voor de Nederlandse is based in Netherlands and operates in the Public Sector sector. Netherlands ranks #22 worldwide for ransomware disclosures, with 147 victims in this database.

Sector context. Organisations in this sector hold valuable data and operational systems that ransomware groups seek to exploit for financial gain through encryption and data exfiltration.

Thegentlemen typically follows a double extortion model: data is exfiltrated from the victim's systems before files are encrypted, so the victim faces two demands at once — pay to restore access, and pay to keep stolen data unpublished. The leak site, where this listing appeared, is the lever for the second demand.

Source. Public leak-site disclosures aggregated via the ransomware.live API. The disclosure date is when the listing was published, which can differ from the date of compromise. This site does not publish or link to stolen data. Last updated .

Frequently asked questions

Was Instituut voor de Nederlandse attacked by ransomware?

Yes. Instituut voor de Nederlandse was listed as a victim of the Thegentlemen ransomware group on May 15, 2026. The organisation is based in Netherlands and operates in the Public Sector sector. The disclosure appeared on the group's dark web leak site.

Which ransomware group attacked Instituut voor de Nederlandse?

Instituut voor de Nederlandse was attacked by Thegentlemen ransomware. Thegentlemen is one of the most active ransomware groups, having claimed 1,081 victims globally. The group typically employs a double-extortion model: encrypting the victim's files and threatening to publish stolen data.

When did the Instituut voor de Nederlandse ransomware attack occur?

The ransomware attack on Instituut voor de Nederlandse was disclosed on May 15, 2026. This date reflects when the victim was published on the threat group's leak site, which may differ from the actual date of initial compromise.

What data was stolen in the Instituut voor de Nederlandse ransomware attack?

The specific data stolen from Instituut voor de Nederlandse has not been independently verified by this platform. Ransomware groups typically exfiltrate data before encrypting systems and use the threat of publication to pressure victims. As a Public Sector organisation, Instituut voor de Nederlandse likely held sensitive business data, client information, and operational records.

How can organisations protect against Thegentlemen attacks?

To defend against Thegentlemen and similar threat actors, organisations should: maintain regular offline backups tested for restoration; implement network segmentation to limit lateral movement; deploy multi-factor authentication on all remote access; use endpoint detection and response (EDR) tools; conduct regular phishing and security awareness training; and monitor threat intelligence feeds for indicators of compromise (IOCs) associated with active groups.