Distributed Denial of Service (DDoS)
May 20, 2023
A Distributed Denial of Service (DDoS) attack is a type of cyber attack that attempts to overwhelm a website, server, or network with a massive amount of traffic, making it inaccessible to users. This type of attack involves multiple devices or computers working in concert to flood a target with traffic, often from many different sources.
Purpose and Usage
The purpose of a DDoS attack is to disrupt the normal operation of a website or network by overwhelming it with a flood of traffic. This can cause the website or network to slow down or become completely unavailable, preventing legitimate users from accessing it.
DDoS attacks are often used as a means of extortion, with the attacker demanding payment in order to stop the attack. They can also be used as a distraction, to divert attention away from other attacks or activities. Additionally, DDoS attacks can be used to gather information about a target, such as identifying vulnerabilities in its security defenses.
How DDoS Attacks Work
There are several different techniques that can be used in a DDoS attack, each with its own specific purpose and effect. The most common types of DDoS attacks include:
Traffic flooding is the most common type of DDoS attack, and involves overwhelming a target with a massive amount of traffic. This can be accomplished by using a botnet, which is a network of computers that have been infected with malware and can be controlled remotely.
Botnets can be used to generate traffic in a wide variety of ways, including sending malformed packets, generating fake traffic, or simply flooding the target with a massive amount of legitimate traffic. In some cases, attackers will use amplification techniques to increase the amount of traffic generated by each bot, making the attack even more effective.
Application Layer Attacks
Application layer attacks target specific vulnerabilities in a website or application. These attacks are typically more sophisticated than traffic flooding attacks, and often require a greater level of technical expertise to execute.
One common type of application layer attack is the HTTP flood, which involves sending a large number of requests to a web server in a short period of time. This can cause the server to become overloaded and unresponsive, effectively taking the website offline.
Protocol attacks target weaknesses in the underlying protocols used by a website or network. These attacks are typically more difficult to execute than traffic flooding or application layer attacks, but can be more effective in certain situations.
One example of a protocol attack is the SYN flood, which involves sending a large number of SYN packets to a target’s server in order to overwhelm its capacity to respond to connection requests. This can effectively prevent legitimate users from accessing the target’s services.
Reflection and Amplification Attacks
Reflection and amplification attacks are a type of DDoS attack that involves exploiting vulnerabilities in third-party systems in order to generate a massive amount of traffic. These attacks are typically more sophisticated than other types of DDoS attacks, and can be more difficult to defend against.
One common example of a reflection and amplification attack is the DNS amplification attack, which involves sending a large number of DNS requests to open resolvers, which then send a large amount of traffic to the target’s server. This can effectively amplify the amount of traffic generated by the attacker, making the attack more difficult to defend against.
Defending Against DDoS Attacks
There are several different strategies that can be used to defend against DDoS attacks, each with its own strengths and weaknesses. Some common strategies include:
Network-level defenses involve filtering traffic at the network level in order to block malicious traffic before it can reach the target server. This can be accomplished using firewalls, routers, and other network-level technologies.
One common network-level defense is the use of blacklists, which are lists of IP addresses or other network identifiers that are known to be associated with malicious traffic. By blocking traffic from these sources, network-level defenses can help to prevent DDoS attacks from reaching their target.
Cloud-based defenses involve using a third-party service provider to filter traffic before it reaches the target server. These services typically use advanced algorithms to detect and block malicious traffic, while allowing legitimate traffic to pass through.
One advantage of cloud-based defenses is that they can scale up to handle very large volumes of traffic, making them particularly effective against large-scale DDoS attacks. They can also be less expensive than other types of defenses, since they don’t require the same level of hardware investment.
Application-level defenses involve filtering traffic at the application level, using specialized software or hardware to identify and block malicious traffic. This can be particularly effective against application layer attacks, which target specific vulnerabilities in a website or application.
One common application-level defense is the use of web application firewalls (WAFs), which are designed to filter traffic at the application level based on a set of predefined rules. By blocking traffic that violates these rules, WAFs can help to prevent DDoS attacks from reaching their target.