What Is a DDoS Attack?

Understanding DDoS Attacks

A Denial-of-Service (DoS) attack is a security incident with the goal of disrupting the normal operations of a server, network, web application, etc., and making it unavailable to legitimate users. This can be achieved with a number of techniques, the most straightforward of them is flooding the target with an overwhelming number of requests, which overloads the system and prevents legitimate requests from being processed.

As the name suggests, a Distributed Denial-of-Service (DDoS) attack involves a number of simultaneous DoS attacks.

While Denial-of-Service can sometimes be unintended or result from minor acts of vandalism, more often than not, the attacks are organized. Common reasons for DDoS attacks include unfair competition, extortion, revenge, and hacktivism.

Types of DDoS Attacks

There are different options for dividing DDoS attacks by type, but from a practical point of view, it is most convenient to divide them into two main categories: DDoS attacks on the network (L3) and transport (L4) layers, and DDoS attacks on the application layer (L7).

• L3/L4 DDoS Attacks: These attacks target the lower layers of the OSI model, specifically the network and transport layers. Common methods include UDP flood, TCP flood, IP flood, ICMP flood, and SYN flood. L3/L4 attacks aim to overwhelm the target’s bandwidth by sending a high volume of packets, causing network congestion and rendering the service unavailable.
• L7 DDoS Attacks: These attacks target the higher application layer, mainly HTTP/HTTPS protocols, which directly handle user requests. Unlike L3/L4 attacks that clog the target’s network connection, L7 DDoS attacks seek to overwhelm the processing capacity of the targeted server, since dealing with HTTP and especially HTTPS requests is a resource-intensive task.

Impact of DDoS Attacks

From a business perspective, successful DDoS attacks have several unpleasant consequences. Short- and medium-term outcomes include direct financial losses due to lost revenue and reduced employee productivity. There are also costs of restoring operations that can be significant. And since DDoS attacks are more and more frequently used by ransomware operators, in some cases paying a ransom may be necessary.

As of long-term consequences, frequent outages damage customer trust and loyalty. Users disappointed by unreliable services may turn to competitors, harming the brand's reputation and market position. DDoS attacks can also strain IT resources, diverting attention from other critical security issues and operational tasks with long-lasting consequences.

Defense Strategies and Tools

To protect against modern sophisticated DDoS attacks, businesses need specialized tools. It should also be mentioned that L3/L4 DDoS attacks and L7 DDoS attacks are very different and therefore require distinct protection methods. With this in mind, let's look at three commonly available strategies for DDoS protection.

• On-Premise Anti-DDoS Equipment: some companies prefer to deploy dedicated hardware within their own infrastructure to handle DDoS attacks. While this approach can offer somewhat better control, it has two significant issues: high cost (both CapEx and OpEx) and limited capacity, which can become problematic during large-scale attacks.
• Telecom Providers' DDoS Protection Services: communication providers often offer DDoS protection as an extra service. Such solutions can be effective in combating network and transport layer (L3/L4) attacks. However, due to the specifics of telecom operators' business they may struggle with more sophisticated application layer (L7) attacks.
• Cloud Anti-DDoS Solutions: thanks to distributed infrastructure, cloud-based solutions offer reliable and scalable DDoS protection with global coverage and low total cost of ownership. What's more, cloud Anti-DDoS services, like those offered by Qrator Labs, are particularly effective against L7 DDoS attacks due to advanced architecture, sophisticated protection algorithms, and extensive expertise in combating even the most complex attacks.