A DDoS (distributed denial-of-service) attack is a type of cyberattack in which a hacker overwhelms a server with an excessive number of requests, causing the server to stop functioning properly. This can cause the website, app, game, or other online service to become slow, unresponsive, or completely unavailable. DDoS attacks can result in lost customers and revenue for the victim. DDoS attacks are becoming increasingly common, with a 46% increase in the first half of 2024 compared to the same period in 2023.
How do DDoS attacks work?
DDoS attacks work by overwhelming and flooding a company’s resources so that legitimate users cannot get through. The attacker creates huge amounts of malicious traffic by creating a botnet, a collection of compromised devices that work together to carry out the attack without the device owners’ knowledge. The attacker, referred to as the botmaster, sends instructions to the botnet in order to implement the attack. The attacker forces these bots to send an enormous amount of internet traffic to a victim’s resource. As a result, the server can’t process real users trying to access the website or app. This causes customer dissatisfaction and frustration, lost revenue, and reputational damage for companies.
Think of it this way: Imagine a vast call center. Someone dials the number but gets a busy tone. This is because a single spammer has made thousands of automated calls from different phones. The call center’s lines are overloaded, and the legitimate callers cannot get through.
DDoS attacks work similarly, but online: The fraudster’s activity completely blocks the end users from reaching the website or online service.
Different types of DDoS attacks
There are three categories of DDoS attacks, each attacking a different network communication layer. These layers come from the OSI (Open Systems Interconnection) model, the foundational framework for network communication that describes how different systems and devices connect and communicate. This model has seven layers. DDoS attacks seek to exploit vulnerabilities across three of them: L3, L4, and L7.
While all three types of attacks have the same end goal, they differ in how they work and which online resources they target. L3 and L4 DDoS attacks target servers and infrastructure, while L7 attacks affect the app itself.
- Volumetric attacks (L3) overwhelm the network equipment, bandwidth, or server with a high volume of traffic.
- Connection protocol attacks (L4) target the resources of a network-based service, like website firewalls or server operating systems.
- Application layer attacks (L7) overwhelm the network layer, where the application operates with many malicious requests, which leads to application failure.
1. Volumetric attacks (L3)
L3, or volumetric, DDoS attacks are the most common form of DDoS attack. They work by flooding internal networks with malicious traffic, aiming to exhaust bandwidth and disrupt the connection between the target network or service and the internet. By exploiting key communication protocols, attackers send massive amounts of traffic, often with spoofed IP addresses, to overwhelm the victim’s network. As the network equipment strains to process this influx of data, legitimate requests are delayed or dropped, leading to service degradation or even complete network failure.
2. Connection protocol attacks (L4)
Protocol attacks occur when attackers send connection requests from multiple IP addresses to target server open ports. One common tactic is a SYN flood, where attackers initiate connections without completing them. This forces the server to allocate resources to these unfinished sessions, quickly leading to resource exhaustion. As these fake requests consume the server’s CPU and memory, legitimate traffic is unable to get through. Firewalls and load balancers managing incoming traffic can also be overwhelmed, resulting in service outages.
3. Application layer attacks (L7)
Application layer attacks strike at the L7 layer, where applications operate. Web applications handle everything from simple static websites to complex platforms like e-commerce sites, social media networks, and SaaS solutions. In an L7 attack, a hacker deploys multiple bots or machines to repeatedly request the same resource until the server becomes overwhelmed.
By mimicking genuine user behavior, attackers flood the web application with seemingly legitimate requests, often at high rates. For example, they might repeatedly submit incorrect login credentials or overload the search function by continuously searching for products. As the server consumes its resources managing these fake requests, genuine users experience slow response times or may be completely denied access to the application.
How can DDoS attacks be prevented?
To stay one step ahead of attackers, use a DDoS protection solution to protect your web resources. A mitigation solution detects and blocks harmful DDoS traffic sent by attackers, keeping your servers and applications safe and functional. If an attacker targets your server, your legitimate users won’t notice any change—even during a considerable attack—because the protection solution will allow safe traffic while identifying and blocking malicious requests.
DDoS protection providers also give you reports on attempted DDoS attacks. This way, you can track when the attack happened, as well as the size and scale of the attack. This enables you to respond effectively, analyze the potential implications of the attack, and implement risk management strategies to mitigate future disruptions.
Repel DDoS attacks with Gcore
At Gcore, we offer robust and proven security solutions to protect your business from DDoS attacks. Gcore DDoS Protection provides comprehensive mitigation at L3, L4, and L7 for websites, apps, and servers. We also offer L7 protection as part of Gcore WAAP, which keeps your web apps and APIs secure against a range of modern threats using AI-enabled threat detection.
Take a look at our recent Radar report to learn more about the latest DDoS attack trends and the changing strategies and patterns of cyberattacks.
