What is DOS Attack?
A Denial of Service (DoS) attack is a type of cyber attack in which an attacker attempts to make a network resource or service unavailable to its intended users.
This is typically accomplished by overwhelming the targeted system with a flood of traffic, either by using a single device to generate a high volume of traffic or by using a botnet, a network of compromised devices that can be controlled remotely to generate traffic. The goal of a DoS attack is to make the targeted service unavailable to legitimate users, disrupting normal business operations and causing financial losses.
The Distributed Denial of Service (DDoS) attack is a variant of the DoS attack, in which the attacker uses a network of compromised devices, or botnet,
to generate a large volume of traffic from multiple sources, making it more difficult to block the traffic and mitigate the attack.
What are the types of DOS attacks?
There are several types of Denial of Service (DoS) attacks, including:
Flooding attacks: These attacks involve overwhelming the targeted system with a high volume of traffic, such as a ping flood, a SYN flood, or a UDP flood.
Amplification attacks: These attacks involve amplifying the traffic sent to the targeted system by using a network of compromised devices,
such as a DNS amplification attack or a NTP amplification attack.
Application-layer attacks: These attacks target specific vulnerabilities in web-based applications, such as a HTTP flood or a Slowloris attack.
Protocol attacks: These attacks exploit vulnerabilities in network protocols, such as a TCP SYN flood or a ICMP flood.
Resource depletion attacks: These attacks aim to consume resources on the targeted system, such as a CPU or memory, making it unavailable for legitimate users.
Zero-day attacks: These are new types of attacks that exploit unknown vulnerabilities in systems or applications.
DDoS (Distributed Denial of Service) attack: These attacks are made by a large number of devices that are controlled remotely to launch the attack on
the targeted system.
Botnet attack: A botnet attack is a type of DDoS attack that uses a network of compromised devices (bots) to generate a high volume of traffic to overwhelm the targeted system.
It is important to note that there can be a combination of the above types of attacks in real-life scenarios.
How to find DOS Vulnerabilities?
As an ethical hacker looking to find a Denial of Service (DoS) vulnerability in a website, there are several methods you can use:
Manual testing: This involves manually sending requests to the website and observing the responses. You can use tools such as a web browser or a command-line tool like cURL to send requests. Look for any signs of the website becoming unresponsive or slow to respond when you send a high volume of requests.
Automated testing: This involves using a tool that automatically sends requests to the website and records the responses. Popular tools for this include Apache JMeter and Gatling. These tools can simulate a high volume of traffic and help you identify any vulnerabilities in the website's infrastructure.
Network analysis: You can use network analysis tools such as Wireshark or tcpdump to capture and analyze network traffic to the website.
This can help you identify any unusual patterns of traffic, such as a high volume of requests from a single IP address.
Vulnerability scanning: You can use a vulnerability scanner such as Nessus or OpenVAS to scan the website for known vulnerabilities that could be exploited in a DoS attack.
Penetration testing: This is a more comprehensive testing method, where you simulate a real-world attack on the website and try to exploit any vulnerabilities you find. This can help you identify any weaknesses in the website's security that could be exploited in a DoS attack.
It is important to note that all of these methods should be done with permission from the website owner and following the ethical guidelines of hacking.
How to prevent DOS attacks?
There are several ways to prevent or mitigate a Denial of Service (DoS) attack:
Firewall and intrusion detection/prevention systems (IDS/IPS) can be used to filter out and block suspicious traffic before it reaches the targeted system or network.
Network rate limiting can be implemented to limit the amount of traffic that can be sent to a targeted system, making it more difficult for an attacker to flood it with a large amount of traffic.
Use of a content delivery network (CDN) can help distribute traffic across multiple servers, reducing the impact of an attack on a single server or system.
Deployment of anti-DDoS services such as Cloudflare or Akamai, that can absorb the attack traffic before it reaches to the target server.
Regularly patching and updating the software and operating system on all systems and devices on a network can help prevent vulnerabilities from being exploited by attackers.
Have an incident response plan ready to use in case of an attack.
It's important to note that no single solution can completely prevent a DoS attack, so it's important to implement multiple layers of defense to mitigate the risk.
Types of payload use in DOS Attacks:
A Denial of Service (DoS) payload is the specific data or code that an attacker uses to launch a DoS attack. There are several types of DoS payloads that can be used to achieve the desired result of overwhelming a targeted system or network:
Ping Flood: A ping flood payload is a type of DoS attack in which the attacker floods a targeted system with a large number of ping requests (ICMP packets) in an attempt to overload it and make it unavailable.
SYN Flood: A SYN flood payload is a type of DoS attack that exploits a weakness in the TCP/IP protocol to overload a targeted system. The attacker sends a large number of SYN packets to the targeted system, causing it to become overwhelmed and unable to process legitimate requests.
HTTP Flood: An HTTP flood payload is a type of DoS attack that targets web servers by flooding them with a large number of HTTP requests.
UDP Flood: A UDP flood payload is a type of DoS attack that floods a targeted system with a large number of UDP packets, overwhelming it and making it unavailable.
Application layer attack: This type of attack is targeted to exploit the vulnerabilities in specific software or application.
It's important to note that many attackers use a combination of payloads to increase the effectiveness of the attack.
List of Top 10+ Denial of Service (DoS) Writeups:
- Long String DOS
- AIRDOS
- Github actions DOS
- Banner grabbing to DOS and memory corruption
- DOS across Facebook endpoints
- DOS on WAF protected sites
- DOS on Facebook android app using zero width no break characters
- Whatsapp DOS vulnerability on android and iOS
- Whatsapp DOS vulnerability in iOS android
If you want to submit your writeups in the list. Submit Here
 Attacks: How to Identify, Prevent, Mitigate and Writeups){kind=link}