A denial of service is a type of cyber attack that aims to make a service, network or system unavailable by flooding it with malicious traffic.
👉 Types of denial of service
There are two main types:
- Denial of Service (DoS) attack From a single source.
- Attack DDoS (Distributed Denial of Service) Uses multiple coordinated sources, often networks of infected machines (botnets).
DDoS attacks are generally more powerful and difficult to counter than simple DoS attacks.
How it works
Denial of service attacks work by overloading the resources of a target system:
- Traffic flooding Mass sending of requests to saturate the bandwidth.
- Operation of vulnerabilities Targeting specific vulnerabilities in systems or applications.
- Amplification attacks Use of third-party servers to amplify the volume of malicious traffic.
💥 Consequences of a denial of service
- Unavailability of services websites and applications become inaccessible to legitimate users.
- Financial losses The impact on sales and costs associated with mitigating the attack.
- Damage to reputation loss of confidence from customers and partners.
- Loss of productivity employees can no longer access the resources they need.
- Increased security risks The attack may mask other malicious activities.
- Potential legal consequences obligation to notify in the event of a data breach (see RGPD)
- Security reinforcement costs Investment needed to improve defences.
💉 Protection and remedies
There are several strategies that can be put in place to protect against DoS and DDoS attacks:
- Traffic monitoring early detection of anomalies.
- Filtering setting up firewall and intrusion detection systems.
- Load sharing traffic distribution over several servers.
- DDoS mitigation services : use of specialised services capable of filtering malicious traffic on a large scale.
- Regular updates Fixing known vulnerabilities.
📊 Figures for France and worldwide
Denial of service attacks are on the increase:
- In France, the number of DDoS attacks increased by 111 % in the first half of 2024 compared with the same period in 2023.
- DNS attacks, a specific type of DDoS, increased by 215 % between the first half of 2023 and the first half of 2024..
- Worldwide, the United States is the hardest hit, accounting for 48.2 % of application DDoS attacks..
- The most targeted sectors are financial services (23.8 %), business (20.1 %) and telecommunications (12.3 %)..
- The average size of DNS amplification attacks increased by 483 % in the second half of 2023 compared to the first half of the same year.
