Distributed denial-of-service (DDoS) attacks involve multiple systems, often compromised by malware, which are used to flood the bandwidth or resources of the targeted system. Unlike a traditional denial-of-service (DoS) attack, which typically originates from a single source or device, a DDoS attack involves multiple systems working together to generate a high volume of traffic or requests to overwhelm the target. DDoS attacks can use a large number of unique IP addresses and machines, potentially numbering in the thousands, to launch the attack. These systems are often referred to as a “botnet,” and they can be controlled remotely by the attacker to coordinate the attack. DDoS attacks can be particularly effective because they can generate a large volume of traffic from multiple sources, making it difficult for the targeted system to distinguish between legitimate and malicious traffic.
There are several different types of DDoS attacks:
- Volumetric attacks: These attacks aim to saturate the bandwidth or resources of the targeted system by generating a high volume of traffic or requests.
- Protocol attacks: These attacks aim to exploit vulnerabilities or weaknesses in the protocol stack of the targeted system. For example, protocol attacks can include SYN flood attacks, which overload the target with incomplete connection requests.
- Application Layer attacks: These attacks target specific applications or services, such as web servers or databases, by generating a high volume of requests or by exploiting vulnerabilities in the application code. For example, sending HTTP requests to a web server to generate computationally expensive responses is a common application layer attack.
- Amplification attacks: These attacks use reflection and amplification techniques to amplify the volume of traffic directed at the target. Amplification attacks can include DNS amplification attacks, which use the Domain Name System (DNS) to send a large number of responses to a single request, and NTP amplification attacks, which use the Network Time Protocol (NTP) to send a large number of responses to a single request
To protect against DoS attacks, it is important to implement measures such as network firewalls or load balancers that can detect and drop malicious traffic as early as possible in the network.