❇️ What is a DDoS attack ?
In a distributed denial-of-service (DDoS) attack, multiple compromised computer systems attack a target and cause a denial of service for users of the targeted resource. The target can be a server, website or other network resource. The flood of incoming messages, connection requests or malformed packets to the target system forces it to slow down or even crash and shut down, thereby denying service to legitimate users or systems.
Many types of threat actors, ranging from individual criminal hackers to organized crime rings and government agencies, carry out DDoS attacks. In certain situations -- often ones related to poor coding, missing patches or unstable systems -- even legitimate, uncoordinated requests to target systems can look like a DDoS attack when they are just coincidental lapses in system performance.
❇️ How do DDoS attacks work ?
- In a typical DDoS attack, the assailant exploits a vulnerability in one computer system, making it the DDoS master. The attack master system identifies other vulnerable systems and gains control of them by infecting them with malware or bypassing the authentication controls through methods like guessing the default password on a widely used system or device.
- A computer or network device under the control of an intruder is known as a zombie, or bot. The attacker creates what is called a command-and-control server to command the network of bots, also called a botnet. The person in control of a botnet is referred to as the botmaster. That term has also been used to refer to the first system recruited into a botnet because it is used to control the spread and activity of other systems in the botnet.
- Botnets can be composed of almost any number of bots; botnets with tens or hundreds of thousands of nodes have become increasingly common. There may not be an upper limit to their size. Once the botnet is assembled, the attacker can use the traffic generated by the compromised devices to flood the target domain and knock it offline.
- The target of a DDoS attack is not always the sole victim because DDoS attacks involve and affect many devices. The devices used to route malicious traffic to the target may also suffer a degradation of service, even if they aren't the main target.
❇️ Types of DDoS attacks
There are three main types of DDoS attacks:
Network-centric or volumetric attacks : These overload a targeted resource by consuming available bandwidth with packet floods. An example of this type of attack is a domain name system amplification attack, which makes requests to a DNS server using the target's Internet Protocol (IP) address. The server then overwhelms the target with responses.
Protocol attacks : These target network layer or transport layer protocols using flaws in the protocols to overwhelm targeted resources. A SYN flood attack, for example, sends the target IP addresses a high volume of "initial connection request" packets using spoofed source IP addresses. This drags out the Transmission Control Protocol handshake, which is never able to finish because of the constant influx of requests.
Application layer : Here, the application services or databases get overloaded with a high volume of application calls. The inundation of packets causes a denial of service. One example of this is an Hypertext Transfer Protocol (HTTP) flood attack, which is the equivalent of refreshing many webpages over and over simultaneously.
❇️ Identifying DDoS attacks
Examples of network and server behaviors that may indicate a DDoS attack are listed below. One or a combination of these behaviors should raise concern:
- One or several specific IP addresses make many consecutive requests over a short period.
- A surge in traffic comes from users with similar behavioral characteristics. For example, if a lot of traffic comes from users of a similar devices, a single geographical location or the same browser.
- A server times out when attempting to test it using a pinging service.
- A server responds with a 503 HTTP error response, which means the server is either overloaded or down for maintenance.
- Logs show a strong and consistent spike in bandwidth. Bandwidth should remain even for a normally functioning server.
- Logs show traffic spikes at unusual times or in a usual sequence.
- Logs show unusually large spikes in traffic to one endpoint or webpage.
❇️ DDoS Attack Tools
There are numerous DDoS attack tools that can create a distributed denial-of-service attack against a target server. The list contains both open source(free) and commercial(paid) DDoS tools.
1. SolarWinds DDoS Attack Tool
- DDoS Attack is a tool that can be used to perform a Distributed Denial of Service attack. This application can monitor the event log from numerous sources to find and detect DDoS activities
2. LOIC (Low Orbit ION cannon)
- LOIC (Low Orbit ION cannon) is open-source software use for DDoS attack. This ddos tool is written in C#. This tool sends HTTP, TCP, and UDP requests to the server.
3. HOIC (High Orbit ION cannon)
- High Orbit Ion Cannon is a free denial-of-service attack tool. It is designed to attack more than one URLs at the same time. This ddos tool helps you to launch DDoS attacks using HTTP (Hypertext Transfer Protocol)
4. DDoSIM DDoS attack software
- DDoSIM (DDoS Simulator) is a tool that is used to create a distributed denial-of-service attack against a target server. It is written in C++ and can be used on the Linux operating system.
5. OWASP HTTP POST Software
- The OWASP (Open Web Application Security Project) HTTP Post software enables you to test your web applications for network performance. It helps you to conduct denial of service from a single DDoS machine online.
6. Tor's Hammer
- Tor's hammer is an application-layer DDoS software program. You can use this ddos online tool to target web applications and a web server. It performs browser-based internet request that is used to load web pages.
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