What Is a DDoS Attack? Full Guide With Real Examples

Attackers use a Distributed Denial-of-Service attack by pushing unwanted traffic to popular service sites. This heavy traffic pushes the site into overload, and it cannot provide services to authentic users. Hackers use this method to slow down websites until they become crippled and can no longer deliver legitimate services.

To learn more about DDoS and other major threats, check out our blog on the top 10 cyber cybersecurity threats and attacks.

Understanding Distributed Denial-of-Service (DDoS) Attacks: A Comprehensive Overview

In today’s well-connected world of the internet, organizations and individuals have become heavily dependent on the functioning of online services for their daily business needs. This dependency makes them vulnerable to attacks such as a Distributed Denial-of-Service (DDoS) attack.

A DDoS attack is a well-structured and highly damaging cyber assault that aims to stop the functionality of an online service, website, server, or network infrastructure by overwhelming it with an uncontrollable flood of traffic. Monitoring such anomalies can be achieved through techniques like network sniffing, which helps security teams analyze traffic patterns and detect unusual spikes indicative of a DDoS attack. To explain it with a real-life example, think of it as a digital version of an unexpected traffic jam on a highway.

Imagine thousands of cars suddenly entering a single lane. This causes legitimate traffic to not get through, everything slows down, and eventually, the road cannot be used. This guide helps illustrate how a DDoS attack brings digital operations to a halt by heavy volume, not by directly hacking into the systems.

How Do DDoS Attacks Work?

Attackers execute DDoS attacks by using a large number of hacked devices. These devices could range from your traditional computers to modern IoT (Internet of Things) devices like smart thermostats, security cameras, and even refrigerators, which are infected with malware. Once under the attacker’s control, they become what’s known as “bots” or “zombies.”

Collectively, these hijacked devices form a botnet. A powerful army of digital soldiers awaits orders. Once activated, every bot in this network starts sending requests to a specific target, such as a company’s server or website. The sheer volume of requests overwhelms the system’s ability to respond, leading to sluggish performance or complete shutdown.

One of the most insidious aspects of DDoS attacks is their camouflage. Because the bots are legitimate internet-connected devices, it becomes very challenging to distinguish between real users and malicious traffic. This makes mitigation especially difficult.

How to Recognize a DDoS Attack?

The signs of a DDoS attack can be deceptively similar to those of legitimate traffic surges. For instance, if your website slows down dramatically or becomes completely unreachable, it may not be immediately clear whether this is due to an attack or an unexpected spike in user visits. However, several red flags can indicate malicious activity:

• A sudden and suspicious increase in traffic from a specific IP address or range can help identify malicious IP addresses.
• An influx of visitors sharing the same device profile, browser, or geolocation.
• Unexplained and repetitive requests for the same web page or endpoint may indicate a potential breach of endpoint security.
• Unnatural traffic patterns, such as spikes occurring at regular intervals (e.g., every 10 minutes).

Analyzing these patterns with traffic monitoring and analytics tools can help detect a DDoS attack in its early stages.

What are the Different Types of DDoS Attacks?

DDoS attacks come in various forms, each targeting different layers of the OSI (Open Systems Interconnection) model, which organizes internet functionality into seven distinct layers — from the physical network up to user-facing applications. Here are the three main categories of DDoS attacks:

1. Application Layer Attacks (Layer 7)

These are the most sophisticated type of DDoS attacks and are specifically designed to crash web applications by overwhelming the server’s ability to handle user requests.

Objective: Exhaust the server’s resources (CPU, memory, or database connections) by sending numerous seemingly legitimate requests.

Example: HTTP Flood Attack
Similar to someone constantly pressing the “refresh” button on a browser — but multiplied by thousands of bots. Each HTTP request seems normal but together they cripple the server’s ability to respond.

These attacks are difficult to detect because they mimic regular user behavior, making it hard to filter out malicious requests without blocking real users.

2. Protocol Attacks (Layers 3 and 4)

These attacks exploit vulnerabilities in the network and transport layers of the OSI model, frequently targeting firewalls, load balancers, and other network infrastructure components.

Objective: Consume server and network resources until they’re no longer able to respond to legitimate traffic.

Example: SYN Flood Attack
This attack takes advantage of the TCP handshake mechanism. An attacker sends many SYN requests to a server but never completes the handshake, causing the server to wait indefinitely and eventually exhaust its available connections.

These are also referred to as state-exhaustion attacks because they drain the resources used to maintain active sessions.

3. Volumetric Attacks

These are the most common and the easiest to detect. The attacker floods the target network with massive amounts of data to saturate the bandwidth.

Objective: Block legitimate traffic by overwhelming the network’s data capacity.

Example: DNS Amplification
By sending DNS requests with the victim’s IP address, attackers trick DNS servers into responding to the victim with much larger responses, thus amplifying the attack.

This is equivalent to prank-calling a restaurant and asking for every item on the menu to be read back to someone else, thousands of times.

How to Mitigate a DDoS Attack?

Successfully mitigating a DDoS attack involves differentiating between good and bad traffic — a deceptively complex task. Here are some of the most effective mitigation strategies:

1. Blackhole Routing- This method involves diverting all traffic (both legitimate and malicious) to a “black hole” or null route, where it is discarded. While this is a fast way to stop the attack, it also causes downtime for legitimate users, making it a last-resort option.

2. Rate Limiting- By limiting the number of requests a user can make in a specific time frame, rate limiting can slow down attack traffic. However, it’s not foolproof, especially against large-scale or multi-vector attacks.

3. Web Application Firewalls (WAF)- A WAF filters and monitors HTTP traffic between a web application and the Internet. Custom rules can block suspicious requests, making it particularly effective against Layer 7 attacks.

4. Anycast Network Diffusion- Anycast is a method of routing traffic to multiple, globally distributed data centers. This disperses attack traffic across various locations, diluting the effect and allowing systems to handle requests more efficiently.

Modern DDoS: Multi-Vector Attacks

Many modern DDoS attacks are multi-vector in nature. This means attackers may use a combination of volumetric, protocol, and application layer attacks simultaneously or in rapid succession. These attacks are specifically designed to confuse defenders and bypass traditional mitigation strategies.

For example, a DNS amplification (targeting layers 3/4) may be followed by or coupled with an HTTP flood (layer 7), stretching the victim’s resources to the limit. Combatting such attacks requires layered defense strategies, real-time monitoring, and intelligent threat filtering.

What is DDoS Defense? A Strategic Investment

Given the sophistication and frequency of DDoS attacks today, companies must view DDoS protection not as a luxury but as a necessity. More importantly, advanced logging and analytics help identify weak points and enhance readiness for future attacks.

You may also want to explore the importance of cybersecurity in business to understand how significant strategies can improve resilience against such threats.

Conclusion

Unlike other attacks, DDoS attacks do not involve any direct hacking; instead, they overload the systems with bot devices. This pushes the system to exhaustion, and services become sluggish, and legitimate users are not able to access them.

As businesses are becoming more and more digital, they are becoming more and more prone to such attacks. To effectively stop these attacks right education and strategy are required. You can contact our team at Cybersics to learn more about this.