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What Are the Warning Signs of a Cyberattack?

Quels sont les signes d'une cyberattaque?

Written By :

  • Guillaume Caron | Expert RCGT
    Guillaume Caron

    Chief Executive Officer VARS - Cybersecurity Risk management consulting

Published on November 25, 2025

•   3 min read

Cyberattacks: ransomware can strike without warning. The ability to recognize the first signs on time can save both your data and reputation.

Every day, the activities of companies of all sizes are paralyzed by an unfortunate mouse click. There are many types of cyberattacks, but ransomware is the most dangerous. Criminals encrypt your files, lock your systems and demand a ransom for releasing them.

Prevention starts with early detection and organizational preparedness.

Recognize the warning signs of a cyberattack

A frozen screen is not always part of a cyberattack. In many instances, the signs become evident several days or weeks before ransomware is deployed.

Some of the most common warning signs include:

  • a sudden slowdown of servers and networks;
  • files that are inexplicably inaccessible or modified;
  • unusual connections at unlikely hours;
  • refused passwords and unexpected password reset requests;
  • repeated security alerts and targeted ransomware emails.

These clues may seem banal, but they’re often the first signs of a compromised system. Without active monitoring, an attack can evolve silently and even lock your entire system.

Why SMEs are prime targets

Contrary to what many believe, cybercriminals don’t target only large organizations.

Most ransomware is opportunistic rather than targeted. Automated robots sweep the Internet for known vulnerabilities and weak passwords. If one of your access points is weak, you can become a target without being chosen.

Hackers primarily exploit:

  • forgotten active accounts with simple passwords;
  • incorrectly configured VPNs;
  • software that hasn’t been updated;
  • logins that were compromised in previous data breaches.

Regardless of the size of your company, attackers take advantage of an opportunity. If your cybersecurity maturity is weak, you will be more vulnerable.

Introduce an ongoing threat detection system

In order to spot a cyberattack in advance, you must detect anomalous behaviour.

This involves implementing ongoing monitoring. Security tools track activity logs on your servers, emails and network access. They cross-reference this information to detect inconsistencies such as simultaneous logins from Montréal and another country.

However, human supervision is still essential. Specialists can interpret alerts and decide what action to take.

Large organizations often have an internal security department known as a Security Operations Center (SOC). For SMEs, outsourcing this monitoring to a specialized team is often the most realistic and cost-effective solution to maintain control.

Use rigorous planning to prevent ransomware

Early detection is the best approach. Being ready to react is key.

When ransomware is deployed, every minute counts. A well-prepared organization will already have:

  • data that is backed up regularly and saved in various locations, including an immutable cloud-based copy;
  • occasional data restoration tests;
  • a response plan that outlines roles and priorities in the event of an incident;
  • automatic systems updates;
  • raised awareness of the most common threats among employees;
  • access controls that limit unnecessary privileges.

This preparation significantly reduces an attack’s impact on an organization’s operations and reputation.

React effectively to a cyberattack

When an attack occurs, coordination becomes crucial.

Your list of crisis unit members should include key individuals in the management, IT, communications and legal departments and an external insurer or expert, as needed.

The crisis unit’s role is to contain the threat, understand the attack’s origin and restore the systems in a secure manner.

And before you activate the crisis unit, you can take certain small steps that could limit the damage such as:

  • immediately disconnecting suspicious devices from the network or Internet without turning them off;
  • notifying the internal individuals concerned to avoid any further spread, as per the incident response plan in place;
  • not deleting any unusual files or messages since they may be useful clues for experts;
  • documenting the observed events (dates, error messages, screenshots, etc.) to facilitate subsequent analysis.

An organization that has planned for such an event before it happens can resume its activities faster and limit losses.

Strengthen your cybersecurity through specialized support

Business leaders who wish to better prepare for cybersecurity incidents can benefit from specialized support every step of the way. This involves evaluating the company’s security posture, detecting vulnerabilities and drafting an action plan that meets its needs.

Taking action before an incident occurs is essentially investing in stability and confidence. A well-structured diagnostic strengthens your organization’s stability, confidence and ability to tackle threats.

This article was written in collaboration with François Caron, Senior Director at Vars, a subsidiary of Raymond Chabot Grant Thornton.

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