The attack surface of a company is no longer limited to the network perimeter. Every SaaS connector, every exposed API, every mobile device enrolled in the information system expands the risk zone. Strengthening a company’s modern cybersecurity requires addressing governance, detection, and regulatory compliance simultaneously, three areas we detail here from an operational perspective.
Network Segmentation and Microsegmentation: Reducing the Blast Radius
Most cybersecurity guides recommend a firewall and antivirus. We observe that these perimeter layers are no longer sufficient once an attacker gains an initial foothold internally. Network microsegmentation isolates each workload in a distinct logical zone, preventing any lateral movement between compromised systems.
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In practical terms, an email server should not be able to communicate directly with the HR database. Every allowed flow must be explicitly declared, with everything else blocked by default. This approach, known as “deny-all, allow-by-exception,” significantly complicates the work of an attacker exploiting a vulnerable service.
For SMEs that outsource part of their infrastructure to the cloud, segmentation also applies to virtual networks (VPC, VNet). Solutions offered by specialized integrators facilitate the deployment of consistent policies across on-premise and cloud environments. Players like those referenced on https://www.ecseri.net/ assist companies in structuring these distributed architectures.
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NIS2 Directive and DORA Regulation: Regulatory Constraints on Incident Management
The NIS2 directive redefines incident notification obligations for thousands of French organizations. Transposed by the ordinance of February 21, 2024, it requires entities classified as “essential” or “important” (health, transport, energy, digital services) to promptly report any significant incident to ANSSI. Non-compliance with this obligation exposes organizations to heavy administrative sanctions.
This framework changes the game regarding internal governance. It is no longer enough to detect an intrusion: the company must have a documented process for qualification, escalation, and notification within constrained timelines.
Particular Case of the Financial Sector with DORA
The DORA regulation, applicable since January 2025, targets banks, insurance companies, payment service providers, and their critical technology suppliers (cloud, data). It imposes regular operational resilience testing, including “red team” exercises on production systems.
The interplay between NIS2 and DORA creates a dual set of constraints for financial actors: ANSSI notification on one side, technical resilience requirements on the other. Affected companies must accurately map which obligations apply to each perimeter of their information system.
- Identify whether the organization falls under NIS2 (sectors listed in the February 2024 ordinance) or DORA (financial entities and critical suppliers)
- Establish an incident notification procedure including regulatory timelines, ANSSI contacts, and qualification criteria
- Document resilience tests and retain proof of execution, as regulatory authorities may require them during an audit
Detection Strategy: EDR, NDR, and SIEM Correlation for SMEs
Deploying antivirus on endpoints does not constitute a detection strategy. Modern threats (double extortion ransomware, attacks on the software supply chain) bypass static signatures. We recommend a three-layer detection architecture.
EDR (Endpoint Detection and Response) analyzes the behavior of processes on each endpoint and server. It detects suspicious executions, abnormal privilege escalations, and unusual outgoing connections. For SMEs, managed EDR solutions provide continuous monitoring without the need to recruit an internal SOC team.
NDR (Network Detection and Response) complements EDR by monitoring network traffic. It identifies communications to command and control servers, data exfiltrations, and internal scans. Correlating EDR and NDR alerts in a SIEM (Security Information and Event Management) drastically reduces false positives and accelerates incident qualification.
Prioritizing Investments According to Maturity
A company that does not yet have EDR has no interest in investing in a SIEM. The logical sequence follows a progression:
- Deploy EDR on all endpoints, including often-overlooked Linux servers
- Enable centralized logging for critical systems (Active Directory, VPN gateway, firewall)
- Implement a SIEM or managed correlation service once log sources are reliable and complete
- Add NDR when network visibility becomes a blind spot identified during a simulation exercise
Cybersecurity Governance: Integrating Data Protection into Business Strategy
Cybersecurity is not an IT project; it is a business risk. As long as top management treats IT security as a technical cost center, budgetary decisions will systematically penalize protection in favor of productivity.
Effective governance relies on a steering committee that brings together management, IT department, and business units. This committee defines risk appetite, validates remediation plans, and monitors coverage indicators (EDR deployment rate, average time to remediate critical vulnerabilities, crisis exercise results).
SMEs without a dedicated CISO can outsource this function. A part-time CISO provides governance expertise without the cost of a permanent position, while ensuring that tool and solution choices remain aligned with actual business risks.
NIS2 and DORA compliance accelerates this movement: management teams that had not yet formalized their cybersecurity risk management strategy are now compelled to do so by regulation. Documenting security posture is no longer optional; it is a legal obligation for an increasing number of companies in France.