What is a DDoS attack?

The term DDoS (Distributed Denial of Service) refers to a distributed denial-of-service attack.
Its goal is simple: to render a website, server, or network unavailable by flooding it with requests from thousands of compromised machines, often grouped together in a botnet.

Unlike a traditional DoS (Denial of Service) attack, which is launched from a single source, a DDoS attack relies on a distributed infrastructure—infected computers, servers, or connected devices—making it more widespread and harder to counter.

These attacks are now among the most common and disruptive, targeting large companies, local governments, and digital service providers alike.

How does a DDoS attack work?

A DDoS attack exploits the capacity limits of an online service—such as bandwidth, computing power, or application resources.
The attacker sends an abnormally high volume of traffic to overwhelm the target, causing the service to become totally or partially unavailable.

The most common attack vectors are:

• Volumetric attacks: bandwidth saturation caused by massive traffic (UDP flood, DNS amplification, NTP, SSDP, etc.).

• Protocol-based attacks: exploitation of vulnerabilities in communication protocols (SYN flood, Ping of Death, IP fragmentation).

• Application-layer attacks: targeting software layers (HTTP flood, multiple GET/POST requests) to exhaust server resources.

DDoS attacks are often automated and can last from a few minutes to several days, sometimes in combination with other threats such as ransom DDoS (extortion to stop the attack).

The Impacts of a DDoS Attack

A DDoS attack does not directly compromise data, but it disrupts service availability, sometimes with critical consequences:

• Service interruption (website, email, business application).

• Loss of revenue due to service downtime.

• Damage to the company's reputation and customer trust.

• Diversion effect: While teams are dealing with the denial-of-service attack, another attack (intrusion, data theft) may be carried out at the same time.

For some companies, a prolonged DDoS attack can bring all digital operations to a standstill or even halt production.

How can you protect yourself against a DDoS attack?

There is no single solution for protecting against a DDoS attack, but a combination of preventive and detection measures can significantly reduce the risks.

1. Prevention and Network Architecture

• Implement firewalls and DDoS filters at the router and ISP levels.

• Configure rate-limiting policies.

• Use content delivery networks (CDNs) to distribute the load.

• Develop business continuity plans and procedures for switching to backup servers.

2. Monitoring and Detection

The ITrust SOC teams use advanced monitoring tools to identify traffic anomalies in real time.
Thanks to Reveelium’s behavioral analysis, it is possible to detect abnormal traffic flows before they reach a critical threshold.

3. Response and Remediation

In the event of an attack, a rapid and coordinated response is essential:

• redirect malicious traffic,

• isolate the affected segments,

• activate mitigation plans through network service providers,

• and analyze attack vectors to strengthen defenses.

Recommendations from Cybersecurity Authorities

Organizations such as ANSSI, CERT-FR, and CISA regularly issue preventive advisories on DDoS threats.
They emphasize the need to:

• monitor network congestion indicators,

• keep equipment up to date,

• work with internet service providers and security providers,

• and raise awareness among technical teams about the early detection of anomalies.

A proactive cybersecurity approach remains the best strategy for dealing with attacks that are often unpredictable.