Top 10 Most Well-Known DDoS Attacks - CloudSecureTech (2025)

Distributed Denial of Service (DDoS) attacks represent one of the most potent threats in today’s cybersecurity landscape. These attacks disrupt online services and can cause significant operational and financial damage.

Recent trends reveal a surge in attack frequency and sophistication, leaving organizations vulnerable to downtime, financial losses, and reputational damage. The average cost of a DDoS attack for businesses in 2023 was estimated at $408,000 per incident, underscoring the severe economic impact.

With DDoS attacks growing in duration and complexity, understanding their scope and preparing defenses are no longer optional—they’re mandatory.

Before we look at the biggest and most famous DDoS attacks in history, let’s first understand the difference between DOS and DDoS.

Understanding the Difference Between DOS and DDoS

The terms Denial of Service (DoS) and Distributed Denial of Service (DDoS) are often used interchangeably, but they differ in scale and intensity.

A Denial of Service (DOS) attack is an aggressive cyber strategy where an attacker aims to render a machine or network resource unavailable, cutting off access for legitimate users by disrupting the services of a host connected to the Internet.

Although effective, recent DOS attacks often go unreported in the public domain due to their relatively small scale and limited impact.

In contrast, a Distributed Denial of Service (DDoS) attack is essentially a DOS attack on steroids. It involves inundating a network with a flood of internet traffic that mimics genuine requests, using a multitude of compromised devices to target and overwhelm a single system.

The scale and intensity of DDoS assaults are far more significant, which is why all the examples in this blog pertain to DDoS attacks alone.

Key Differences between DoS and DDoS:

• DoS: A single system floods a network.
• DDoS: Multiple devices coordinate a simultaneous attack, making it far more challenging to counter.
• Scale and complexity: DDoS attacks involve thousands of compromised devices, which are often difficult to trace.

Understanding these differences is crucial for choosing the appropriate mitigation strategies. For instance, DDoS attacks require more sophisticated multi-layered defense systems that can identify and neutralize malicious traffic from multiple sources.

What Was the Largest DDoS Attack of All Time?

To date, the largest DDoS attack example occurred in 2020, when Amazon Web Services (AWS) faced a staggering 2.3 Tbps attack. The attack lasted several days but caused minimal disruption thanks to AWS’s defensive capabilities.

This incident underscores how well-prepared organizations can absorb even the most massive attacks. Modern DDoS defenses must be capable of handling such high-volume attacks to maintain uptime and operational stability.

Let’s take a closer look at some other big and famous DDoS attacks in the past.

10 Well-Known Examples of Distributed Denial of Service Attacks (DDoS)

These famous DDoS attacks exemplify the breadth of targets—from tech giants to government agencies—and the need for robust security frameworks. Here’s a quick overview of the top 10 attacks discussed in this blog.

To understand the significance of these famous DDoS attacks, let’s take a deep dive into examining each case in more detail.

1. Dyn (2016)

In October 2016, a DDoS attack struck at the heart of the Internet, DNS provider Dyn, bringing down popular sites like Twitter, Reddit, and Netflix. The attackers used a vast botnet called Mirai to infiltrate thousands of poorly secured IoT devices and bombard the DNS provider Dyn with junk data, shutting out millions of users.

This attack laid bare serious vulnerabilities in the infrastructure we’ve come to depend on. It demonstrated how devices, from IoT devices to web-enabled appliances, can be co-opted for disruption when security is an afterthought.

Impact: The attack caused widespread disruption of legitimate internet activity, affecting millions of users worldwide. It highlighted the vulnerability of the internet infrastructure and the potential for IoT devices to be exploited in DDoS attacks.

2. GitHub (2018)

Source: GitHub

GitHub was hit by a massive DDoS attack that peaked at 1.35 Tbps. The attackers exploited memcached servers to amplify the attack, a technique that was relatively new at the time.

Impact: GitHub was briefly knocked offline, but the attack was mitigated within 10 minutes. The attack demonstrated the potential for new DDoS techniques to cause significant disruption, even to well-protected targets.

3. BBC (2015)

In December 2016, the BBC was the target of a DDoS attack that made the broadcaster’s websites and web-based products inaccessible for several hours. The BBC’s entire domain, including its on-demand iPlayer for television and radio programming, was knocked offline during the incident.

A hacking collective known as New World Hacking claimed responsibility, stating they orchestrated the attack to demonstrate their capabilities.

Impact: The outage prevented access for millions of BBC site and app users, underscoring the ability of DDoS tactics to cause major disruptions to media services. The BBC attack illustrates the challenges organizations face in mitigating and defending against attacks that flood servers with junk traffic to deny legitimate access.

4. Spamhaus (2013)

Spamhaus, a non-profit organization that tracks spam operations, was hit by an attack that peaked at 300 Gbps. The attack was reportedly in retaliation for Spamhaus blacklisting the Dutch hosting company Cyberbunker.

Impact: While Spamhaus itself was able to stay online, the attack caused significant disruption to the wider internet, affecting millions of users. This DDoS example highlights the potential for attacks to be used as a form of retaliation.

5. Cloudflare (2020)

Cloudflare, a major provider of distributed denial-of-service (DDoS) protection services, was targeted by an attack that reached a peak intensity of 754 million packets per second.

This latest DDoS attack leveraged a novel tactic involving the abuse of CLDAP servers to amplify the scale of the junk traffic used to overwhelm Cloudflare’s systems.

This attack underscores the ongoing race between DDoS tool developers and defenders to maintain availability in the face of ever-more-powerful assaults. Adaptive and multilayered controls represent key strategies for mitigating modern DDoS threats.

Impact: Despite the massive flood of packets generated by the perpetrators, Cloudflare successfully mitigated the attack without any noticeable degradation to its services or customer websites under its protection.

6. Amazon Web Services (2020)

AWS was hit by a DDoS attack that lasted for three days and peaked at 2.3 Tbps. The attackers exploited CLDAP servers to amplify the attack.

Impact: Despite the scale and duration of the attack, AWS was able to mitigate it without any major disruption to its services. This DDoS example demonstrates the potential for even the largest and most well-protected targets to be hit by DDoS attacks.

7. Google (2017)

Google was the target of a highly sophisticated DDoS attack campaign that lasted approximately six months and is considered unprecedented in its scale and intensity.

At its peak, the attack directed a 2.5 Tbps flood of traffic across thousands of Google IP addresses spanning multiple geographic regions. According to Google’s analysis, the attack was sponsored by a nation-state actor.

Impact: Google stated that its defenses successfully detected and mitigated the attack without major disruption. The attack highlights the growing operational capabilities of state-sponsored actors to deliver devastating DDoS at a massive scale.

8. GitHub (2015)

In 2015, GitHub was the target of a five-day DDoS campaign that intermittently disrupted services on the popular code repository site. Investigation revealed that state-sponsored actors were likely behind the exploit, which specifically targeted two GitHub projects aimed at helping users in a particular geographic area circumvent state censorship controls.

The incident highlights how DDoS tactics can potentially be utilized as a form of censorship when deployed against sites hosting content deemed unfavorable by state entities.

Impact: While GitHub, through mitigation measures, remained online throughout most of the attack, periodic outages over the five-day period prevented some users from accessing the site.

9. Estonia (2007)

A three-week-long DDoS attack targeted the entire country of Estonia. The attack was reportedly carried out by state-sponsored actors and targeted government, media, and financial websites.

Impact: The attack caused significant disruption to Estonia’s online infrastructure, affecting millions of users. It was one of the first examples of a large-scale, state-sponsored DDoS attack.

10. Code Spaces (2014)

Code Spaces, a code hosting and software collaboration platform, was targeted by a DDoS attack that was part of a larger extortion attempt. When Code Spaces attempted to mitigate the attack, the attackers deleted most of their data and backups.

Impact: The attack targeted Code Spaces’s data and led to its closure. It highlighted the potential for DDoS attacks to be used as part of larger, more destructive attacks.

How Are DDoS Attacks Measured?

DDoS attacks are measured primarily in bits per second (bps). This metric indicates the volume of traffic that attackers direct toward the target.

Large-scale DDoS attacks, like those targeting major corporations or governments, can reach terabits per second (Tbps), overwhelming even the most well-prepared defenses.

The rise in the scale of DDoS attacks in recent times is significant. For instance, the average DDoS attack length in 2023 increased by 400% compared to 2022.

More sophisticated attacks last longer and are increasingly difficult to mitigate. This is why measuring and understanding attack intensity is essential for designing a robust response.

Key Metrics in Measuring DDoS Attacks

Here are the critical metrics used for measuring DDoS attacks and their severity.

The True Cost of DDoS Attacks

The financial and reputational costs of DDoS attacks can be catastrophic. Several reports confirmed that the average DDoS attack cost businesses nearly half a million dollars in 2023.

However, damages can be much higher in some industries, such as telecommunications and finance, due to extended downtimes and the critical nature of their services.

Key Factors Driving DDoS Attack Costs:

• Downtime: Every minute of downtime now costs an average of $9,000.

• Reputation damage: Extended outages can erode customer trust.

• Recovery costs: Post-attack mitigation, including forensic analysis and upgrades to defenses, can be expensive.

The stakes are high for any organization. However, by implementing proactive measures such as real-time monitoring and traffic filtering, you can significantly reduce these risks.

Breakdown of DDoS Attack Costs

Why Are DDoS Attacks Launched?

DDoS attacks can be launched for several reasons, such as financial gain or a distraction to cover more insidious activities.

Hacktivists, organized crime, and some state actors have all employed DDoS attack examples for different purposes in history.

Some of the most common DDoS attack motivations include:

Financial Interests Propel Numerous DDoS Attacks

Often, DDoS attacks are a means to an economic end. Cybercriminals use these tactics to extort money from companies by halting the onslaught only when paid off. In some scenarios, they might be contracted by competitors to hinder a business rival’s operations. The pursuit of financial rewards is a common incentive for many who orchestrate DDoS attacks.

Political and Cyber Warfare Motives

DDoS attacks can be instruments for those pursuing political goals or engaging in cyber warfare. Activists may deploy DDoS attacks to draw attention to a cause or to disrupt the activities of specific organizations or governments. Similarly, nation-states may utilize these attacks within broader cyber warfare tactics, aiming to disrupt critical infrastructure and sow chaos.

The Lure of Disruption

There are instances where individuals or groups execute attacks purely for the disruption they cause, driven by a desire for excitement or notoriety within certain circles. These perpetrators often initiate attacks as a challenge or to boast about their capabilities in the hacker community.

Distraction for Further Malfeasance

At times, DDoS attacks are diversions, creating a shield of chaotic traffic under which other nefarious activities can occur. With the defensive efforts focused on DDoS response, attackers might engage in data theft or network infiltration unnoticed.

How the Right IT and Cybersecurity Partner Can Help

In the current digital era, the question isn’t if a DDoS attack will occur but when.

Given their potentially devastating impact on business operations and reputation, a robust defense strategy is not just advisable; it’s imperative. This is where the right IT and cybersecurity partner becomes invaluable.

Partnering with a trusted IT and cybersecurity firm can be the difference between successfully mitigating a DDoS attack and suffering extensive downtime. The right partner provides a multi-layered defense strategy and a quick response team to neutralize threats.

The most important benefits of cybersecurity partners include the following:

Proactive Protection Measures

A seasoned IT and cybersecurity firm specializes in laying down multiple layers of defense to safeguard your assets before an attack occurs. These measures include setting up firewalls and intrusion detection systems and configuring network architecture to absorb and diffuse a DDoS attack’s impact.

Immediate Response and Mitigation

When an attack is detected, time is of the essence. An experienced partner will have the capabilities to immediately recognize the signs of a DDoS attack and swiftly enact mitigation strategies. These can range from rerouting traffic and filtering out malicious packets to deploying anti-DDoS technology that can counteract an ongoing attack.

Regular System Updates and Patch Management

Keeping systems updated with the latest security patches is a fundamental yet often neglected aspect of cybersecurity. An IT partner ensures that your systems are not left vulnerable due to outdated software, providing an additional safeguard against the exploitation of known vulnerabilities.

24/7 Monitoring and Support

Continuous monitoring is critical for early detection of unusual activity that could signal the onset of a DDoS attack. A dedicated cybersecurity team can monitor your network around the clock and respond in real-time to potential threats.

Education and Training

Knowledge is a powerful defense. A cybersecurity partner can educate your staff about the signs of a DDoS attack and train them in best practices for prevention and response. Empowering employees with this knowledge can be the difference between a minor incident and a catastrophic one.

Recovery and Post-Attack Analysis

After an attack, it’s crucial to return to normal operations as quickly as possible. A competent IT partner helps with recovery efforts and conducts a post-incident analysis to identify how the attack happened and how to prevent similar incidents in the future.

Strategic Planning for Long-Term Security

Finally, beyond the immediate threat of DDoS attacks, a strategic IT and cybersecurity partner works with you to plan for long-term digital security. This includes regular assessments, updates to your security policies, and the evolution of your defense measures to meet emerging threats.

Engaging an expert cybersecurity partner gives you peace of mind, knowing that your business is well-protected against potential threats.

Conquer the Inevitable With Expert Security Advice

As attacks keep growing, it’s clear that the consequences of underestimating the threat of DDoS are dire. With an average attack costing businesses upwards of $400,000 and some attacks reaching over 2 Tbps, proactive prevention is the best strategy.

If you’re serious about fortifying your defenses, contact CloudSecureTech today. Let’s connect you to security experts that will shield your business from DDoS threats.

FAQ

What is the Most Common DoS Attack?

The most common example of a DDoS attack is the SYN flood attack. This involves overwhelming a server with incomplete TCP handshake requests, rendering it unable to respond to legitimate traffic.

What is the Oldest DDoS Attack?

One of the oldest famous DDoS attacks was the 1999 Trinoo attack. In this incident, attackers used thousands of compromised computers to launch coordinated attacks on multiple systems, setting the stage for future DDoS techniques.

As attacks keep growing, it’s clear that the consequences of underestimating the threat of DDoS are dire. With an average attack costing businesses upwards of $400,000 and some attacks reaching over 2 Tbps, proactive prevention is the best strategy.

If you’re serious about fortifying your defenses, contact CloudSecureTech today. Let’s connect you to security experts that will shield your business from DDoS threats.