I. Defining the context of the threat
1. Definition of the risk
Ransomware is a cyberattack consisting of encrypting the data of an IT system (workstations, servers, backups) to make them completely inaccessible to the victim company.
Attackers then demand a ransom, usually in cryptocurrency, in exchange for a decryption key.
Modern ransomware attacks go beyond simple encryption. They frequently incorporate double extortion strategies, combining:
- Data encryption, blocking activity,
- Theft of sensitive information (clients, HR, financial data),
- Threat of publication or resale of data, increasing pressure on the company.
The main infection vectors are:
- Phishing emails containing malicious links or attachments,
- Poorly secured remote access (RDP, VPN without MFA),
- Unpatched vulnerabilities in systems or software,
- Compromise of privileged accounts, facilitating internal spread.
2. Importance and current trend
Ransomware is now considered one of the most critical cyber threats for companies across all sectors.
Its impact is particularly severe because it can:
- Completely block activity, sometimes for several days,
- Cause significant financial losses,
- Lead to breaches of sensitive data,
- Engage the legal responsibility of the organization.
Attacks increasingly target:
- SMEs, often less well protected,
- Hospitals and public institutions, whose activity is critical,
- Industries and essential service companies, where activity stoppage has a strong economic impact.
3. Concrete examples of ransomware attacks
🔹 Healthcare sector
Many hospitals have suffered attacks paralyzing their IT systems, forcing staff to revert to manual procedures, directly impacting continuity of care and patient safety.
🔹 Industrial and logistics sector
Some attacks have led to a complete stoppage of production or distribution chains for several days, causing significant economic losses and major delays.
🔹 Service companies
Companies have seen their client data encrypted and exfiltrated, resulting in:
- Data breach notifications,
- Loss of client trust,
- Regulatory sanctions.
These cases demonstrate that ransomware is not a theoretical risk, but a real and recurring operational threat.
II. Technical foundations of the topic: Focus on encryption and ransomware
Ransomware relies mainly on the abusive use of legitimate cryptographic mechanisms, normally designed to protect data.
1. Encryption used by ransomware
Attackers generally use:
- Symmetric encryption (e.g., AES) to quickly encrypt large volumes of files,
- Asymmetric encryption (e.g., RSA) to protect the decryption key.
The private key, essential for data recovery, is kept by the attacker, making any restoration impossible without backup or payment.
2. Identity and access management (prevention)
Secure password management
- Storage via secure hashing to prevent password reading,
- Implementation of robust password policies,
- Reuse prohibition, limiting cascading attacks.
Multi-factor authentication (MFA)
- MFA strongly reduces the risk of account compromise, even if a password is stolen,
- Essential for:
- Remote access,
- Admin accounts,
- Cloud environments.
Centralized identity management
- Use of directories like Active Directory or OpenLDAP,
- Clear separation between user and administrator accounts,
- Application of the principle of least privilege.
3. Backups and protection against encryption
Backups
- Regular, tested, documented backups,
- Offline or immutable copies, inaccessible from the main network,
- Key element to ensure business recovery without paying ransom.
Network segmentation
- Reduces lateral movement of the attacker,
- Reinforces protection of critical systems.
4. Detection and incident response
- EDR/XDR solutions capable of detecting abnormal file encryption,
- Analysis of suspicious attachments and downloads,
- Rapid isolation of compromised workstations to limit propagation,
- Centralized supervision via logging and security tools.
III. Possible impacts on the company
1. Risk scenarios
🔻 Activity stoppage
- Critical systems unavailable,
- Production or services interrupted,
- Customer relationship degraded.
🔻 Financial losses
- Technical remediation costs,
- Revenue loss,
- Legal and crisis management expenses.
🔻 Data loss or exposure
- Customer data,
- Sensitive internal data,
- Intellectual property.
🔻 Reputation damage
- Loss of trust of clients and partners,
- Long-term commercial impact.
🔻 Regulatory consequences
- Legal obligations to report,
- Sanctions in case of non-compliance (GDPR).
2. Risk matrix
| Type of risk | Probability | Impact | Example |
|---|---|---|---|
| Data encryption | High | Very high | Unavailable servers |
| Activity stoppage | Medium | Very high | Production stopped |
| Data leak | Medium | High | Exposed client data |
| Damage to reputation | Medium | Medium | Loss of trust |
| Regulatory sanctions | Low | High | Non-compliance with GDPR |
Glossary of key terms
🔐 Double extortion
Double extortion is a technique used in ransomware attacks.
Besides encrypting data, attackers steal sensitive information (client data, internal documents) and threaten to publish or sell it if the ransom is not paid.
➡️ Even with backups, the company remains under pressure.
🌐 RDP (Remote Desktop Protocol)
RDP allows remote connection to a computer as if physically present.
→ Poorly secured (weak password, no MFA) becomes a privileged entry point for attackers.
🔒 VPN (Virtual Private Network)
A VPN creates a secure connection between a user and the company network via the Internet.
→ If VPN access is compromised, attackers can enter the internal network.
🎯 Infection vector
An infection vector is the method used by an attacker to enter an IT system.
Examples: phishing email, malicious attachment, poorly protected remote access, outdated software.
→ Starting point of the attack.
🔐 AES (Advanced Encryption Standard)
AES is a standard, legally recognized encryption algorithm used to protect data.
→ Ransomware uses it to quickly encrypt victim files.
🔑 RSA
RSA is an encryption algorithm used to secure keys.
→ In ransomware, it protects the AES decryption key held only by the attacker.
⚖️ Notification obligation
Companies must report personal data breaches to authorities (e.g., CNIL) and sometimes to affected individuals.
→ Non-compliance may result in legal and financial sanctions.
IV. Policies implemented to mitigate ransomware risk
- Backups and data resilience
- Systematic backup of critical data, with offline or isolated copies,
- Regularly tested for rapid service recovery without paying ransom,
- Separation between production and backup environments to limit major incident impact.
- Network segmentation and architecture
- Limits ransomware propagation within the information system,
- Critical resources isolated in dedicated segments with strict flow rules.
- Detection and supervision
- Continuous detection via centralized supervision tools (SIEM, EDR),
- Quickly identify suspicious behaviors such as mass file encryption or unusual access.
- Incident response
- Formalized procedures, roles, containment actions, internal/external communication, and recovery steps,
- Regular exercises to test and improve effectiveness.
- Governance and risk management
- Cybersecurity governance integrates ransomware risk at a strategic level,
- Dedicated officer (e.g., CISO) coordinates implementation and monitoring.
V. The human factor in ransomware and data encryption risk
Human factor also plays a central role in ransomware attacks. Even with strong security systems, a simple human error can trigger massive infection.
1. Lack of awareness and training
Many employees are not trained in risks related to attachments, suspicious links, or insecure downloads.
2. Human errors and bad practices
- Weak or reused passwords,
- Missing software updates,
- Use of unknown USB drives,
- Downloading unofficial software.
3. Real examples of ransomware attacks linked to the human factor
Example: Villefranche-sur-Saône Hospital (2020)
A ransomware paralyzed the hospital’s IT systems after an employee opened a malicious email. Data was encrypted, forcing temporary manual procedures.
Human factor: opening an infected file without prior verification.
4. Human consequences of ransomware attacks
Ransomware attacks create strong psychological pressure: stress, fear of errors, work overload during return to manual procedures, feelings of powerlessness when data is inaccessible for several days.
5. Importance of awareness and best practices
- Train employees to recognize suspicious emails and files,
- Implement regular, offline backups,
- Apply strict update and access management rules,
- Raise awareness that human prevention is as important as technical protection.
VII. Pentest, controls, and audits (Ransomware)
For ransomware, audits and tests focus on the technical resilience of the information system and the company’s ability to recover quickly after an attack.
| Type | Example / Description | Objective | Source |
|---|---|---|---|
| Intrusion pentest | Exploitation of vulnerabilities (RDP, unpatched flaws) | Identify possible ransomware entry points | https://www.enisa.europa.eu/topics/csirts-in-europe/glossary/ransomware |
| Backup control | Verification of offline backups and restoration tests | Ensure business recovery without paying ransom | https://www.cybermalveillance.gouv.fr/tous-nos-contenus/actualites/ransomware |
| EDR / antivirus audit | Evaluation of ransomware behavioral detection | Block mass file encryption | https://www.crowdstrike.com/cybersecurity-101/ransomware/ |
| Patch audit | Verification of security patch management | Reduce exploitation of known vulnerabilities | https://www.anssi.gouv.fr/fr/dossier/ransomware |
| Continuity tests (PRA/PCA) | Simulation of a ransomware incident | Evaluate continuity and recovery capability | https://www.ssi.gouv.fr/guide/plan-de-reprise-dactivite/ |
These audits are essential because ransomware can completely paralyze a company, cause major financial losses, and engage its legal responsibility.
(ssi.gouv.fr)
(enisa.europa.eu)
(cyber.gouv.fr)
(cyber.gouv.fr)
(crowdstrike.com)
(anssi.gouv.fr)
(ssi.gouv.fr)
(cnil.fr)