Denial Of Service (DoS)

What Is Denial Of Service (DoS) Attacks? – How Does It Works And More

If you’ve ever wondered about Denial of Service (DoS) attacks – how they function, their history, and ways to protect yourself – you’ve come to the right place. This easy-to-understand exposé aims to provide insights into one of the most prevalent cyber threats.

What Is A DoS Attack?

A Denial of Service (DoS) attack involves a deliberate effort by hackers to restrict or entirely halt web traffic to a specific website, server, or online service. One common method is the Distributed Denial of Service (DDoS) attack, where numerous computers overwhelm a server with data, rendering it unresponsive and effectively shutting down its services.

But Why Do People Launch DoS Attacks?

The motives vary, ranging from cyber-activism, pranks, ransom threats, and extortion attempts to distractions for more severe hacking activities. DoS attacks have targeted financial institutions, electronic outlets, video games, religious groups, governments, and more.

How Does A Distributed Denial Of Service (DDoS) Attack Work?

A Distributed Denial of Service (DDoS) attack is like overwhelming a highway with too many cars, causing a traffic jam and slowing everything down. To understand how this works, let’s break it down using a simple analogy.

Internet Basics

Imagine the internet as a network of tubes. Whenever you do something online, like sending a message or visiting a website, your computer communicates with another computer or server. These tubes have a limited capacity, known as bandwidth. Larger tubes allow more data to flow faster.

Collision Domain and Exponential Backoff

To prevent congestion, we use something called Collision Domain, which divides the network into interconnected tubes. Think of water spreading across tubes – data behaves similarly. The second safeguard is Exponential Backoff. If a tube is full, your computer waits before trying again, increasing the wait time each attempt.

What’s A DDoS Attack?

A DDoS attack aims to clog a server’s tubes with so much data that it either slows down or becomes inaccessible. To achieve this, a massive amount of data is needed, often in the form of computers trying to access a server simultaneously. This coordinated effort is orchestrated using a botnet.


A botnet is a network of compromised computers worldwide, controlled by a hacker. These computers, infected with malware, can be commanded to perform various tasks, including DDoS attacks. They provide the necessary firepower to overwhelm a server.


Rather than directly attacking the target, hackers use “reflectors.” Innocent computers receive misleading connection requests from the botnet and, thinking the target server is reaching out, respond. This creates a flood of traffic. Using reflectors adds a protective layer for attackers, making it challenging to trace them.

Application Layer DDoS Attacks

Hackers can target specific sections of a website or service, known as application layer DDoS attacks. This tactic aims to shut down particular features, distracting IT professionals while more critical hacks occur.

The IoT Problem

As more devices connect to the internet, botnets can grow larger. The Internet of Things (IoT) has expanded the opportunities for DDoS attacks. More devices mean more chances to flood a server with data, making DDoS attacks more prevalent in today’s interconnected world.

Other Kinds of DoS Attacks

While Distributed Denial of Service (DDoS) attacks are prevalent, various other tools and techniques exist to execute Denial-of-Service attacks. Here’s a brief overview of some alternative methods:

1. Teardrop Attacks: Send mangled IP addresses and oversized data packets to slow down or crash the target computer.

2. Banana Attacks: Create a feedback loop by forcing outgoing messages back into the target, causing chaos.

3. Smurf Attacks: Exploit misconfigured network devices to send massive files simultaneously, overwhelming the network.

4. PDoS (Permanent Denial of Service) Attacks: Involve hacking into IoT devices and replacing firmware with something corrupt or defective.

5. Nukes: Send corrupt error messages or operational information data to slow down and freeze the target.

6. Peer-to-Peer Attacks: Hackers break into a target’s network, instructing all connected devices to connect to a single website or server simultaneously.

7. Ping Floods: Send a huge number of pings from one computer to another, a simple yet common attack, especially in online games.

8. Degradation-of-Service Attacks: Botnets attack a website in waves, causing frequent and unpredictable slowdowns.

9. HTTP POST Attacks: An obsolete method involves broadcasting data so slowly that it impedes other data.

10. Denial-of-Service Level 2 Attacks: Trick a target’s defense mechanism to block the network from the internet, taking everything offline.

11. Ping of Death: A malicious, oversized ping causing some systems to crash when handling it.

12. Amplification Attacks: Manipulate publicly accessible DNS to send traffic to unprepared sites.

13. Slowloris (or RUDY): Hog as many connections as possible to limit availability to legitimate users.

14. Shrew Attacks: Target the Transmission Commission Protocol with quick bursts of activity to exploit timeout mechanisms.

Who Is Targeted By DoS Attacks?

Individuals are generally not targeted by DoS attacks. These attacks focus on servers to take down specific websites or any others incidentally hosted on the targeted server. DoS attacks lack financial or practical benefits for random targets, typically having a specific purpose. Unless hosting controversial data or being a controversial figure, the average person need not worry about becoming a target.

Are DoS Attack Legal?

In theory, performing a DoS attack is considered a crime, albeit not a severe one. It could lead to imprisonment and hefty fines, with potential additional charges for serious cases. While some argue it should be a form of protest, in the US and UK, getting caught performing a DoS attack can bring legal consequences. However, the legality becomes murky in practice, as governments and organizations sometimes use DoS attacks for cyber warfare or testing server capacity and cybersecurity teams. Regardless, engaging in DoS attacks is unlawful and can result in legal trouble.

Famous Examples Of DoS Cases

1. Project Rivolta — Turn-of-the-Century Terror

On February 7th, 2000, a Canadian hacker named Mafiaboy launched a massive DoS attack (Project Rivolta), taking down major websites for a week. The attack had significant repercussions, leading to Mafiaboy’s arrest and emphasizing the vulnerability of the internet.

2. The 2007 Estonia Attacks — The First Cyberwar

Estonia faced widespread DoS attacks in 2007, impacting banks, newspapers, and government entities. Russia was implicated due to the origin of the attacks, highlighting the use of DoS attacks in cyber warfare.

3. Project Chanology — Rebels with a Cause

Project Chanology marked the first use of DoS attacks as a form of protest by the group Anonymous against Scientology in 2008. This event inspired subsequent online protests and demonstrated the potential impact of DoS attacks in activism.

4. The 2014 PlayStation Network Attack — Setting an Example

Lizard Squad’s DDoS attack on the PlayStation Network in 2014, while smaller than previous breaches, significantly damaged consumer trust in Sony. This attack followed a major hack in 2011, emphasizing the recurring threat.

5. The 2014 Hong Kong Cyberwar — An Attack Like No Other

During the Occupy Central protests in Hong Kong, independent press websites were DDoS’d for months. The prolonged attack showcased the potential for DoS attacks as tools of political oppression.

Protecting Against DoS Attacks: A Simple Guide

For Individual Users:

1. Guarding Against Botnets:

   To shield your computer from becoming part of a botnet:

   – Install Antivirus Software: Use reputable antivirus software to detect and eliminate potential threats.
   – Enhance Router Security: Strengthen your router settings to fortify your home network against unauthorized access.

2. Password Management:

   To reduce the risk of direct contribution to DoS attacks:

   – Regular Password Updates: Frequently change passwords on your connected devices, making it harder for unauthorized access.

For Servers and Web Administrators:

1. Dead Traffic Management:

   Preventing dead traffic from causing disruptions:

   – Redirect to a “Black Hole” Server: Channel non-essential traffic to a non-existent server, minimizing impact.

2. Bandwidth Management Tools:

   Identifying and blocking potentially harmful data packets:

   – Utilize Bandwidth Management Tools: Employ tools to scrutinize data packets, identifying and blocking those that pose risks.

3. Upstream Filters with Scrubbing Centers:

   Filtering out bad connections effectively:

   – Implement Upstream Filters: Establish filters equipped with scrubbing centers to distinguish between good and harmful connections.

4. Additional Bandwidth Rental:

   Enhancing capacity during heightened traffic:

   – Rent Extra Bandwidth: In times of increased traffic due to attacks, renting additional bandwidth ensures continued service availability.

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