Distributed Denial of Service (DDoS) attack is a malicious attempt to disrupt the regular functioning of a targeted online service. A website, network, or server can be vulnerable by overwhelming it with an excessive amount of traffic. The goal of a DDoS attack is to render the targeted system unavailable to its intended users. By consuming its resources, it can no longer respond to legitimate requests.

In a DDoS attack, the “distributed” aspect refers to the use of a multitude of compromised computers and devices. These often referred to as a “botnet,” to flood the target with traffic. These compromised devices can include computers, servers, IoT (Internet of Things) devices, and even smartphones. The attackers take control of these devices without the owners’ knowledge. They use various methods such as malware infections, phishing attacks, or exploiting vulnerabilities.

The attack traffic generated by the compromised devices is often coordinated and sent simultaneously. This overwhelms the target’s infrastructure and makes it difficult for legitimate users to access the service. The attack traffic takes various forms. These include, web requests, network packets, or even specially crafted messages designed to exploit vulnerabilities in the target’s systems.

DDoS attacks can vary in terms of their scale and complexity. Some common types of DDoS attacks include:

  1. Volumetric Attacks: These involve flooding the target with a massive amount of data, such as a large number of requests. Also flooding network packets, to exhaust its bandwidth capacity.
  2. TCP/UDP Floods: These attacks target the network protocols, overwhelming the target with a flood of TCP or UDP packets, making it difficult for the server to establish and maintain connections.
  3. Application Layer Attacks: Also known as Layer 7 attacks, these target the application layer of a service by sending complex requests that exploit vulnerabilities in the application’s code, consuming server resources and causing it to become unresponsive.
  4. Spoofed Attacks: In these attacks, the attacker spoofs the source IP addresses of the attacking traffic to make it appear as if the traffic is coming from legitimate sources, making it harder to mitigate the attack.
  5. Amplification Attacks: These attacks take advantage of certain vulnerable services that respond with a larger amount of data than they receive. The attacker sends a small request to the vulnerable service with a spoofed source IP, causing the service to send a much larger response to the target.

To defend against DDoS attacks, organizations often deploy specialized security solutions, such as DDoS protection services and appliances, that can identify and mitigate malicious traffic patterns. These solutions help filter out the attack traffic and ensure that legitimate users can still access the targeted service.