Attack alert: qilin targets Peter Meijer Architect - NL

Introduction

The Dutch architecture firm Peter Meijer Architect has suffered a data breach orchestrated by the qilin ransomware group, revealed on December 4, 2025. This compromise, classified as SIGNAL level according to the XC-Classify protocol, affected a small firm of 1 to 10 employees specializing in the management of sensitive plans and confidential real estate projects. The incident occurs within a context where the architecture sector in the Netherlands is becoming a prime target for malicious actors, attracted by the strategic value of design data and private client information. According to our data certified on the Polygon blockchain, this attack raises crucial questions about the protection of small firms against sophisticated ransomware operating on the Ransomware-as-a-Service (RaaS) model.

The breach comes as qilin intensifies its operations against European AEC (Architecture, Engineering, Construction) firms, exploiting the vulnerabilities of SMEs that are often under-equipped in terms of cybersecurity. For Peter Meijer Architect, the implications extend far beyond a simple technical breach: exclusive architectural plans, data on high-net-worth clients, and details of ongoing real estate projects constitute highly sensitive information assets, the disclosure of which could jeopardize years of work and client trust.

Analyse détaillée

The SIGNAL classification indicates a targeted threat requiring heightened vigilance, particularly in a sector where project confidentiality represents a major competitive advantage. This attack illustrates the vulnerability of independent architecture firms to modern cyberattacks, at a time when European regulatory requirements, including the GDPR and the NIS2 Directive, impose strict obligations regarding data protection and incident notification.

Analysis of this breach reveals the specific challenges faced by small Dutch professional firms, confronted by cybercriminal adversaries with considerable resources and advanced technical expertise. → Understanding XC criticality Levels allows for a precise assessment of the urgency and scope of the response measures required for this type of incident.

The Qilin group, also known as Agenda, has established itself as one of the most active and sophisticated ransomware collectives in 2025. Operating according to the Ransomware-as-a-Service (RaaS) model, this cybercriminal organization offers its malicious infrastructure to affiliates, thus creating a decentralized ecosystem that is difficult for authorities to dismantle. This approach allows Qilin to multiply its operations while minimizing risks to its core operations.

Qilin's Tactics, Techniques, and Procedures (TTPs) reveal a refined methodology: the collective prioritizes the exploitation of zero-day vulnerabilities and targeted phishing campaigns to gain initial access to systems. Once inside, attackers deploy advanced reconnaissance tools to map the compromised network, identifying high-value data before initiating the encryption process. Their operational signature is double extortion: massive exfiltration of sensitive files followed by system encryption, thus creating maximum pressure on victims.

Qilin's history shows a marked preference for European targets, particularly in the healthcare, professional services, and construction sectors. The group has compromised dozens of organizations since its emergence, publicly displaying its victims on a dedicated website hosted on the dark web. This "name and shame" strategy aims to force targeted organizations to quickly pay ransoms, under threat of having their confidential data publicly disclosed.

Qilin's RaaS (Radio-as-a-Service) architecture means that attacks are often carried out by affiliates with varying skill sets, explaining the diversity of attack vectors observed. Some intrusions exploit vulnerabilities in poorly secured Remote Desktop Protocol (RDP) services, while others involve compromising corporate VPN accounts or exploiting weaknesses in exposed web applications. → Full analysis of the qilin group details the evolution of their techniques and recent campaigns.

Peter Meijer Architect represents the typical profile of an independent Dutch architecture firm: a small structure (1 to 10 employees) specializing in architectural design and real estate project management for a demanding private clientele. Based in the Netherlands, the firm operates in a highly competitive market where reputation and confidentiality are major strategic assets.

The firm's activities encompass the creation of bespoke architectural plans, the management of residential and commercial construction projects, as well as design and planning consulting. This expertise requires the daily handling of highly sensitive data: detailed plans of private properties, clients' financial information, contractual details of ongoing projects, and confidential correspondence with contractors and suppliers. The very nature of this information makes it a prime target for malicious actors.

The organization's small size, while allowing for significant operational flexibility, also presents a cybersecurity vulnerability. Firms of this size rarely have dedicated IT security resources, often relying on standardized solutions and outsourced IT support. This economic reality creates blind spots in the security posture, particularly against sophisticated adversaries like Qilin.

Peter Meijer Architect's Dutch presence places the organization under the jurisdiction of strict European data protection regulations. The GDPR imposes rigorous obligations regarding the security of clients' personal information, while the NIS2 directive, applicable to entities in the construction sector, strengthens cybersecurity and incident notification requirements.

The compromise of such a firm generates multidimensional impacts: potential loss of intellectual property (exclusive designs), exposure of private client data (contact information, budgets, preferences), disclosure of sensitive contractual details, and major reputational damage in a sector where trust is the foundation of business relationships. For a small organization, the financial and operational consequences of such an attack can be catastrophic, threatening the very viability of the business.

The SIGNAL classification assigned by the XC-Classify protocol indicates a data exposure requiring immediate attention, although the exact extent of the compromise is still being analyzed. This criticality level suggests that sensitive information has been exfiltrated by the attackers, but without reaching the volume or sensitivity thresholds of the higher levels (PARTIAL or FULL).

Data compromised in an attack against an architecture firm typically includes several critical categories: detailed architectural plans representing months of creative work, CAD (Computer-Aided Design) files containing precise technical specifications, email correspondence with clients revealing budgets and personal requirements, contracts and quotes exposing profit margins, and potentially personally identifiable information (PII) from high-net-worth clients.

Review of available metadata suggests that Qilin likely deployed its standard technical arsenal: initial reconnaissance of the compromised network, privilege escalation to access central file servers, methodical exfiltration of data identified as sensitive to command and control servers, and then deployment of the encryption payload. The precise timeline of the intrusion remains to be determined, but Qilin's operations typically extend over several weeks, allowing attackers to maximize exfiltration before detection.

Conclusion

The discovery of the incident on December 4, 2025, raises questions about the time lag between the initial compromise and its detection. This latency, often called "dwell time," is a critical indicator: the longer it is, the more time attackers had to explore the network, exfiltrate data, and compromise backup systems. For small organizations like Peter Meijer Architect, the lack of advanced detection solutions (EDR, SIEM) typically extends this timeframe significantly.