Faced with the rise of ransomware, companies must balance operational urgency with legal requirements. How can they respond effectively?
A company can see its business paralyzed overnight after a malware intrusion that blocks access to essential data. This cyber threat, known as ransomware, is increasingly targeting professionals across all sectors. Here’s what this digital scourge entails and what best practices to adopt in order to respond effectively in the event of an intrusion.
What is ransomware?
Ransomware is malicious software that blocks access to an organization’s data or systems and demands a ransom for their return.
Cybercriminals mainly use two methods of pressure, often in combination: file encryption, which makes the company’s data completely inaccessible and paralyzes its business, and data exfiltration, which involves stealing sensitive information before encrypting it, with the threat of publishing it if the ransom is not paid.
These attacks most often penetrate via carefully crafted phishing campaigns, corrupted attachments, or the exploitation of unpatched security vulnerabilities. Insufficiently protected remote access accounts are also a frequent entry point for these intrusions.
Ransomware: what are the consequences for businesses?
A ransomware attack triggers a crisis with multiple consequences, often far more costly than the ransom itself. Its impact goes far beyond the technical realm and falls into three main categories.
Operational and financial impact: the paralysis of business activity generates immediate losses in revenue. The company also incurs high remediation costs for cyber expertise and rebuilding its information system. The permanent loss of critical data threatens the continuity of its business.
Legal and compliance risks: Civil liability actions by affected customers or partners may follow. The company must also comply with legal obligations to report the incident to the authorities.
Damage to brand image and trust: the company’s reputation suffers lasting damage. This mistrust translates into an erosion of confidence among its customers and partners. The organization often experiences future business losses and encounters difficulties in conquering new markets.
Protocol for responding to a ransomware attack
When a ransomware attack occurs, there is no room for improvisation. A structured and rapid response, based on a defined protocol, is essential to contain the crisis, secure the environment, and begin restoring services.
Ransomware: how can you protect yourself in advance?
To avoid being caught off guard by a ransomware attack, it is recommended that you adopt a proactive security strategy. Several technical and organizational measures can significantly reduce the risk of a successful attack and limit its impact.
Regular and isolated backups: setting up automated and frequent backups of critical data is essential. Physically or logically isolating them from the main network protects them from being encrypted or destroyed during an attack.
Systematic security updates: Immediately applying patches released by software and operating system publishers closes technical loopholes that cybercriminals exploit. This rule applies to all IT equipment.
Team training and awareness: Employees are the first line of defense against phishing. Regular training helps them identify suspicious emails and adopt the right security habits in their daily use of digital tools.
Access and privilege control: the principle of least privilege should guide the allocation of access rights. Each user should only have the permissions strictly necessary for their tasks, thus limiting the spread of any intrusion within the network.
Ransomware: how to respond in the event of an attack?
Detecting a ransomware attack triggers a race against time. The first instinct might be to pay the ransom in order to quickly restore access to services, but this practice is strongly discouraged by European authorities. Indeed, it risks financing criminal activities without guaranteeing data recovery. It also exposes the organization to the risk of repeated targeting.
A methodical and rapid response can contain the damage and enable business recovery.
Immediate network isolation: the top priority is to disconnect the infected machine from the network, then cut off global Internet access. This prevents the malware from spreading to backups and other equipment. It is recommended to put affected devices into hibernation rather than shutting them down completely in order to preserve evidence in memory.
Assess the extent of the damage: Technical teams must precisely identify the systems, data, and business processes affected by encryption or exfiltration. This analysis determines the actual operational impact and prepares restoration actions.
Alerting stakeholders: the crisis management plan activates the IT service provider’s response and alerts management and legal departments. Reporting to authorities such as ANSSI and filing a complaint are mandatory steps, particularly in the event of a personal data breach.
Restoration from backups: recovery involves completely reinstalling compromised systems from a healthy image. Data is then restored from a recent offline backup, which has been checked beforehand to ensure its integrity. A general change of passwords concludes this phase.
Last modified: January 28, 2026
