What is a DDoS attack?


DDoS (Distributed Denial of Service) attacks are cyberattacks designed to render an online service, website or even network infrastructure unavailable by overwhelming it with a massive flood of requests. These requests generally come from a network of infected computers, known as botnets, which act together to saturate the target’s resources. This leads to significant slowdowns, or even a complete shutdown of services. The attackers’ aim is to temporarily deprive legitimate users of access to the services in question, often with financial and operational consequences for the victims.

DDoS attacks do not require direct penetration of the targeted system, making them particularly easy to execute compared with other forms of cyber attack. They have become a ubiquitous threat in 2024, affecting businesses and critical infrastructures alike, and their complexity is growing all the time.

How do DDoS attacks work?
The principle of a DDoS attack is based on volume and coordination. By infecting a large number of devices (computers, servers, connected objects, etc.), cybercriminals can form a botnet, a network of “zombie” devices which, once activated, sends a massive volume of traffic to the target. These devices are often compromised without their owners’ knowledge, making the botnet even more effective and difficult to trace.

DDoS attacks are particularly dangerous because of their ability to paralyze an entire network, not only by blocking access to the targeted site, but also by disrupting communications between systems and users. Depending on their type and objective, attacks can be carried out for short or long periods, and their scale can range from a few gigabytes to several terabits per second.

Different types of DDoS attack
There are several categories of DDoS attack, each exploiting specific weaknesses in the target system. Here are the three most common types:

Volumetric attacks
Volumetric attacks are the simplest to understand and execute. Their main objective is to consume the available bandwidth between the target infrastructure and the Internet. They rely on a huge amount of artificially generated traffic to overwhelm the network and prevent services from functioning properly. This saturation can come from legitimate requests repeated on a massive scale, or from completely useless data, such as UDP (User Datagram Protocol) packets.

The scale of this type of attack can rapidly exceed the capacity of a conventional network. In 2024, certain volumetric attacks reached record levels, exceeding 30 terabits per second, making their mitigation extremely complex and requiring very robust defense infrastructures.

Protocol attacks
Protocol attacks aim to exhaust the resources of a server or network device by exploiting weaknesses in communication protocols. They focus on exploiting standard communication mechanisms, such as TCP/IP (Transmission Control Protocol/Internet Protocol). A common example is the SYN Flood attack, in which the attacker floods the server with partially open connection requests, exhausting its resources.

These attacks are more difficult to detect and counter, as they often take place under legitimate appearances. The server, thinking it is receiving normal requests, devotes resources to each request until it is exhausted.

Application attacks
Application attacks are more sophisticated and target the application layer directly, i.e. the application or service itself. These attacks are highly specific and rely on complex requests to overload particular functions of a web application. A common example is an attack on an API that bombards the service with complex requests, requiring a lot of server processing.

These attacks are often difficult to identify, as they mimic normal user behavior, but at an abnormally high frequency. For example, an e-commerce site could be inundated with add-to-cart requests or product inquiries, bringing the system to its knees under an immense load, without it appearing at first glance to be an attack.

The consequences of DDoS attacks in 2024
In 2024, DDoS attacks are no longer limited to disrupting websites. They have become a tool for massive disruption in critical sectors such as finance, healthcare infrastructure, telecommunications and public services. The impacts are varied: significant financial losses due to the unavailability of services, loss of confidence among users and business partners, and, in some cases, more serious consequences such as disruptions to essential public services.

What’s more, the ability of attacks to exceed 30 Tbps shows that these incidents can no longer be countered by conventional solutions alone. Defenses must be multi-layered, integrating cloud-based DDoS protection services, artificial intelligence systems capable of detecting and blocking attacks in real time, and proactive security practices, such as rigorous management of exposed systems.