Distributed Denial of Service
Introduction
A Distributed Denial of Service (DDoS) attack is a malicious attempt to disrupt the normal functioning of a network, service, or website by overwhelming the target or its surrounding infrastructure with a flood of internet traffic. DDoS attacks achieve effectiveness by utilizing multiple compromised computer systems as sources of traffic. The machines can include computers and other networked resources such as IoT devices.
Mechanism of Action
A DDoS attack involves three parties: the target, the attacker, and multiple controlled machines, which form what is known as a botnet. The attacker sends instructions to the compromised machines in the botnet to send traffic to the target, causing it to become overwhelmed and unavailable to its intended users.
Botnets
A botnet is a group of internet-connected devices, each of which is running one or more bots. Botnets can be used to perform DDoS attacks, steal data, send spam, and allows the attacker to access the device and its connection. The owner can control the botnet using command and control (C&C) software. The word "botnet" is a combination of the words "robot" and "network".
Types of DDoS Attacks
There are several types of DDoS attacks, which can be broadly classified into three categories: volume-based attacks, protocol attacks, and application layer attacks.
Volume-Based Attacks
Volume-based attacks aim to overwhelm the bandwidth of the targeted system. Examples of volume-based attacks include UDP floods, ICMP (Ping) floods, and other spoofed-packet floods.
Protocol Attacks
Protocol attacks, also known as state-exhaustion attacks, cause a service disruption by consuming all the available state table capacity of web application servers or intermediate resources like firewalls and load balancers. Examples include SYN flood, fragmented packet attacks, Ping of Death, Smurf DDoS and more.
Application Layer Attacks
Application layer attacks, also known as layer 7 DDoS attacks, target the layer where web pages are generated on the server and delivered in response to HTTP requests. One of the most common types of application layer attacks is the HTTP flood.
Mitigation and Defense
Defending against a DDoS attack is usually a complex task due to the distributed nature of the attack. However, several strategies and techniques can be employed to mitigate the effects of a DDoS attack.
Network Architecture
Having a robust and secure network architecture is the first line of defense against DDoS attacks. This includes having redundant network resources, balancing the load across multiple data centers, and implementing hardware redundancy.
Firewalls and Routers
Firewalls and routers can be configured to reject traffic that originates from known malicious IP addresses or contains malicious content. This is a basic form of DDoS mitigation but can be effective against less sophisticated attacks.
DDoS Defense Systems
Specialized DDoS defense systems and software solutions can be used to detect and mitigate DDoS attacks. These systems can identify patterns and signatures in network traffic that indicate a DDoS attack and respond accordingly.
Impact of DDoS Attacks
DDoS attacks can have a significant impact on businesses and organizations. The immediate effect of a DDoS attack is the disruption of services, which can lead to loss of revenue and reputation. In addition, the resources required to mitigate and recover from a DDoS attack can be substantial.