Welcome to the 18th edition of the Cloudflare DDoS Threat Report. Released quarterly, these reports provide an in-depth analysis of the DDoS threat landscape as observed across the Cloudflare network. This edition focuses on the second quarter of 2024.

With a 280 terabit per second network located across over 320 cities worldwide, serving 19% of all websites, Cloudflare holds a unique vantage point that enables us to provide valuable insights and trends to the broader Internet community.

• Cloudflare recorded a 20% year-over-year increase in DDoS attacks.

• 1 out of every 25 survey respondents said that DDoS attacks against them were carried out by state-level or state-sponsored threat actors.

• Threat actor capabilities reached an all-time high as our automated defenses generated 10 times more fingerprints to counter and mitigate the ultrasophisticated DDoS attacks.

View the interactive version of this report on Cloudflare Radar.

Before diving in deeper, let's recap what a DDoS attack is. Short for Distributed Denial of Service, a DDoS attack is a type of cyber attack designed to take down or disrupt Internet services, such as websites or mobile apps, making them unavailable to users. This is typically achieved by overwhelming the victim's server with more traffic than it can handle — usually from multiple sources across the Internet, rendering it unable to handle legitimate user traffic.

Diagram of a DDoS attack

To learn more about DDoS attacks and other types of cyber threats, visit our Learning Center, access previous DDoS threat reports on the Cloudflare blog or visit our interactive hub, Cloudflare Radar. There's also a free API for those interested in investigating these and other Internet trends.

To learn about our report preparation, refer to our Methodologies.

In the first half of 2024, we mitigated 8.5 million DDoS attacks: 4.5 million in Q1 and 4 million in Q2. Overall, the number of DDoS attacks in Q2 decreased by 11% quarter-over-quarter, but increased 20% year-over-year.

Distribution of DDoS attacks by types and vectors

For context, in the entire year of 2023, we mitigated 14 million DDoS attacks, and halfway through 2024, we have already mitigated 60% of last year’s figure.

Cloudflare successfully mitigated 10.2 trillion HTTP DDoS requests and 57 petabytes of network-layer DDoS attack traffic, preventing it from reaching our customers’ origin servers.

DDoS attacks stats for 2024 Q2

When we break it down further, those 4 million DDoS attacks were composed of 2.2 million network-layer DDoS attacks and 1.8 million HTTP DDoS attacks. This number of 1.8 million HTTP DDoS attacks has been normalized to compensate for the explosion in sophisticated and randomized HTTP DDoS attacks. Our automated mitigation systems generate real-time fingerprints for DDoS attacks, and due to the randomized nature of these sophisticated attacks, we observed many fingerprints being generated for single attacks. The actual number of fingerprints that was generated was closer to 19 million – over ten times larger than the normalized figure of 1.8 million. The millions of fingerprints that were generated to deal with the randomization stemmed from a few single rules. These rules did their job to stop attacks, but they inflated the numbers, so we excluded them from the calculation.

HTTP DDoS attacks by quarter, with the excluded fingerprints

This ten-fold difference underscores the dramatic change in the threat landscape. The tools and capabilities that allowed threat actors to carry out such randomized and sophisticated attacks were previously associated with capabilities reserved for state-level actors or state-sponsored actors. But, coinciding with the rise of generative AI and autopilot systems that can help actors write better code faster, these capabilities have made their way to the common cyber criminal.

In May 2024, the percentage of attacked Cloudflare customers that reported being threatened by a DDoS attack threat actor, or subjected to a Ransom DDoS attack reached 16% – the highest it’s been in the past 12 months. The quarter started relatively low, at 7% of customers reporting a threat or a ransom attack. That quickly jumped to 16% in May and slightly dipped in June to 14%.

Percentage of customers reporting DDoS threats or ransom extortion (by month)

Overall, ransom DDoS attacks have been increasing quarter over quarter throughout the past year. In Q2 2024, the percentage of customers that reported being threatened or extorted was 12.3%, slightly higher than the previous quarter (10.2%) but similar to the percentage of the year before (also 12.0%).

Percentage of customers reporting DDoS threats or ransom extortion (by quarter)

75% of respondents reported that they did not know who attacked them or why. These respondents are Cloudflare customers that were targeted by HTTP DDoS attacks.

Of the respondents that claim they did know, 59% said it was a competitor who attacked them. Another 21% said the DDoS attack was carried out by a disgruntled customer or user, and another 17% said that the attacks were carried out by state-level or state-sponsored threat actors. The remaining 3% reported it being a self-inflicted DDoS attack.

Percentage of threat actor type reported by Cloudflare customers, excluding unknown attackers and outliers

In the second quarter of 2024, China was ranked the most attacked country in the world. This ranking takes into consideration HTTP DDoS attacks, network-layer DDoS attacks, the total volume and the percentage of DDoS attack traffic out of the total traffic, and the graphs show this overall DDoS attack activity per country or region. A longer bar in the chart means more attack activity.

After China, Turkey came in second place, followed by Singapore, Hong Kong, Russia, Brazil, and Thailand. The remaining countries and regions comprising the top 15 most attacked countries are provided in the chart below.

15 most attacked countries and regions in 2024 Q2

The Information Technology & Services was ranked as the most targeted industry in the second quarter of 2024. The ranking methodologies that we’ve used here follow the same principles as previously described to distill the total volume and relative attack traffic for both HTTP and network-layer DDoS attacks into one single DDoS attack activity ranking.

The Telecommunications, Services Providers and Carrier sector came in second. Consumer Goods came in third place.

15 most attacked industries in 2024 Q2

When analyzing only the HTTP DDoS attacks, we see a different picture. Gaming and Gambling saw the most attacks in terms of HTTP DDoS attack request volume. The per-region breakdown is provided below.

Top attacked industries by region (HTTP DDoS attacks)

Argentina was ranked as the largest source of DDoS attacks in the second quarter of 2024. The ranking methodologies that we’ve used here follow the same principles as previously described to distill the total volume and relative attack traffic for both HTTP and network-layer DDoS attacks into one single DDoS attack activity ranking.

Indonesia followed closely in second place, followed by the Netherlands in third.

15 largest sources of DDoS attacks in 2024 Q2

Despite a 49% decrease quarter-over-quarter, DNS-based DDoS attacks remain the most common attack vector, with a combined share of 37% for DNS floods and DNS amplification attacks. SYN floods came in second place with a share of 23%, followed by RST floods accounting for a little over 10%. SYN floods and RST floods are both types of TCP-based DDoS attacks. Collectively, all types of TCP-based DDoS attacks accounted for 38% of all network-layer DDoS attacks.

Top attack vectors (network-layer)

One of the advantages of operating a large network is that we see a lot of traffic and attacks. This helps us improve our detection and mitigation systems to protect our customers. In the last quarter, half of all HTTP DDoS attacks were mitigated using proprietary heuristics that targeted botnets known to Cloudflare. These heuristics guide our systems on how to generate a real-time fingerprint to match against the attacks.

Another 29% were HTTP DDoS attacks that used fake user agents, impersonated browsers, or were from headless browsers. An additional 13% had suspicious HTTP attributes which triggered our automated system, and 7% were marked as generic floods. One thing to note is that these attack vectors, or attack groups, are not necessarily exclusive. For example, known botnets also impersonate browsers and have suspicious HTTP attributes, but this breakdown is our initial attempt to categorize the HTTP DDoS attacks.

Top attack vectors (HTTP)

In Q2, around half of all web traffic used HTTP/2, 29% used HTTP/1.1, an additional fifth used HTTP/3, nearly 0.62% used HTTP/1.0, and 0.01% for HTTP/1.2.

Distribution of web traffic by HTTP version

HTTP DDoS attacks follow a similar pattern in terms of version adoption, albeit a larger bias towards HTTP/2. 76% of HTTP DDoS attack traffic was over the HTTP/2 version and nearly 22% over HTTP/1.1. HTTP/3, on the other hand, saw a much smaller usage. Only 0.86% of HTTP DDoS attack traffic were over HTTP/3 — as opposed to its much broader adoption of 20% by all web traffic.

Distribution of HTTP DDoS attack traffic by HTTP version

The vast majority of DDoS attacks are short. Over 57% of HTTP DDoS attacks and 88% of network-layer DDoS attacks end within 10 minutes or less. This emphasizes the need for automated, in-line detection and mitigation systems. Ten minutes are hardly enough time for a human to respond to an alert, analyze the traffic, and apply manual mitigations.

On the other side of the graphs, we can see that approximately a quarter of HTTP DDoS attacks last over an hour, and almost a fifth last more than a day. On the network layer, longer attacks are significantly less common. Only 1% of network-layer DDoS attacks last more than 3 hours.

HTTP DDoS attacks: distribution by duration

Network-layer DDoS attacks: distribution by duration

Most DDoS attacks are relatively small. Over 95% of network-layer DDoS attacks stay below 500 megabits per second, and 86% stay below 50,000 packets per second.

Distribution of network-layer DDoS attacks by bit rate

Distribution of network-layer DDoS attacks by packet rate

Similarly, 81% of HTTP DDoS attacks stay below 50,000 requests per second. Although these rates are small on Cloudflare’s scale, they can still be devastating for unprotected websites unaccustomed to such traffic levels.

Distribution of HTTP DDoS attacks by request rate

Despite the majority of attacks being small, the number of larger volumetric attacks has increased. One out of every 100 network-layer DDoS attacks exceed 1 million packets per second (pps), and two out of every 100 exceed 500 gigabits per second. On layer 7, four out of every 1,000 HTTP DDoS attacks exceed 1 million requests per second.

The majority of DDoS attacks are small and quick. However, even these attacks can disrupt online services that do not follow best practices for DDoS defense.

Furthermore, threat actor sophistication is increasing, perhaps due to the availability of Generative AI and developer copilot tools, resulting in attack code that delivers DDoS attacks that are harder to defend against. Even prior to the rise in attack sophistication, many organizations struggled to defend against these threats on their own. But they don’t need to. Cloudflare is here to help. We invest significant resources – so you don’t have to – to ensure our automated defenses, along with the entire portfolio of Cloudflare security products, to protect against existing and emerging threats.

Welcome to the 17th edition of Cloudflare’s DDoS threat report. This edition covers the DDoS threat landscape along with key findings as observed from the Cloudflare network during the first quarter of 2024.

But first, a quick recap. A DDoS attack, short for Distributed Denial of Service attack, is a type of cyber attack that aims to take down or disrupt Internet services such as websites or mobile apps and make them unavailable for users. DDoS attacks are usually done by flooding the victim's server with more traffic than it can handle.

To learn more about DDoS attacks and other types of attacks, visit our Learning Center.

Quick reminder that you can access previous editions of DDoS threat reports on the Cloudflare blog. They are also available on our interactive hub, Cloudflare Radar. On Radar, you can find global Internet traffic, attacks, and technology trends and insights, with drill-down and filtering capabilities, so you can zoom in on specific countries, industries, and networks. There’s also a free API allowing academics, data sleuths, and other web enthusiasts to investigate Internet trends across the globe.

To learn how we prepare this report, refer to our Methodologies.

Key insights from the first quarter of 2024 include:

• 2024 started with a bang. Cloudflare’s defense systems automatically mitigated 4.5 million DDoS attacks during the first quarter — representing a 50% year-over-year (YoY) increase.

• DNS-based DDoS attacks increased by 80% YoY and remain the most prominent attack vector.

• DDoS attacks on Sweden surged by 466% after its acceptance to the NATO alliance, mirroring the pattern observed during Finland's NATO accession in 2023.

We’ve just wrapped up the first quarter of 2024, and, already, our automated defenses have mitigated 4.5 million DDoS attacks — an amount equivalent to 32% of all the DDoS attacks we mitigated in 2023.

Breaking it down to attack types, HTTP DDoS attacks increased by 93% YoY and 51% quarter-over-quarter (QoQ). Network-layer DDoS attacks, also known as L3/4 DDoS attacks, increased by 28% YoY and 5% QoQ.

2024 Q1: Cloudflare mitigated 4.5 million DDoS attacks

When comparing the combined number of HTTP DDoS attacks and L3/4 DDoS attacks, we can see that, overall, in the first quarter of 2024, the count increased by 50% YoY and 18% QoQ.

DDoS attacks by year and quarter

In total, our systems mitigated 10.5 trillion HTTP DDoS attack requests in Q1. Our systems also mitigated over 59 petabytes of DDoS attack traffic — just on the network-layer.

Among those network-layer DDoS attacks, many of them exceeded the 1 terabit per second rate — almost on a weekly basis. The largest attack that we have mitigated so far in 2024 was launched by a Mirai-variant botnet. This attack reached 2 Tbps and was aimed at an Asian hosting provider protected by Cloudflare Magic Transit. Cloudflare’s systems automatically detected and mitigated the attack.

The Mirai botnet, infamous for its massive DDoS attacks, was primarily composed of infected IoT devices. It notably disrupted Internet access across the US in 2016 by targeting DNS service providers. Almost eight years later, Mirai attacks are still very common. Four out of every 100 HTTP DDoS attacks, and two out of every 100 L3/4 DDoS attacks are launched by a Mirai-variant botnet. The reason we say “variant” is that the Mirai source code was made public, and over the years there have been many permutations of the original.

Mirai botnet targets Asian hosting provider with 2 Tbps DDoS attack

In March 2024, we introduced one of our latest DDoS defense systems, the Advanced DNS Protection system. This system complements our existing systems, and is designed to protect against the most sophisticated DNS-based DDoS attacks.

It is not out of the blue that we decided to invest in this new system. DNS-based DDoS attacks have become the most prominent attack vector and its share among all network-layer attacks continues to grow. In the first quarter of 2024, the share of DNS-based DDoS attacks increased by 80% YoY, growing to approximately 54%.

DNS-based DDoS attacks by year and quarter

Despite the surge in DNS attacks and due to the overall increase in all types of DDoS attacks, the share of each attack type, remarkably, remains the same as seen in our previous report for the final quarter of 2023. HTTP DDoS attacks remain at 37% of all DDoS attacks, DNS DDoS attacks at 33%, and the remaining 30% is left for all other types of L3/4 attacks, such as SYN Flood and UDP Floods.

Attack type distribution

And in fact, SYN Floods were the second most common L3/4 attack. The third was RST Floods, another type of TCP-based DDoS attack. UDP Floods came in fourth with a 6% share.

Top attack vectors

When analyzing the most common attack vectors, we also check for the attack vectors that experienced the largest growth but didn’t necessarily make it into the top ten list. Among the top growing attack vectors (emerging threats), Jenkins Flood experienced the largest growth of over 826% QoQ.

Jenkins Flood is a DDoS attack that exploits vulnerabilities in the Jenkins automation server, specifically through UDP multicast/broadcast and DNS multicast services. Attackers can send small, specially crafted requests to a publicly facing UDP port on Jenkins servers, causing them to respond with disproportionately large amounts of data. This can amplify the traffic volume significantly, overwhelming the target's network and leading to service disruption. Jenkins addressed this vulnerability (CVE-2020-2100) in 2020 by disabling these services by default in later versions. However, as we can see, even 4 years later, this vulnerability is still being abused in the wild to launch DDoS attacks.

Attack vectors that experienced the largest growth QoQ

Another attack vector that’s worth discussing is the HTTP/2 Continuation Flood. This attack vector is made possible by a vulnerability that was discovered and reported publicly by researcher Bartek Nowotarski on April 3, 2024.

The HTTP/2 Continuation Flood vulnerability targets HTTP/2 protocol implementations that improperly handle HEADERS and multiple CONTINUATION frames. The threat actor sends a sequence of CONTINUATION frames without the END_HEADERS flag, leading to potential server issues such as out-of-memory crashes or CPU exhaustion. HTTP/2 Continuation Flood allows even a single machine to disrupt websites and APIs using HTTP/2, with the added challenge of difficult detection due to no visible requests in HTTP access logs.

This vulnerability poses a potentially severe threat more damaging than the previously known HTTP/2 Rapid Reset, which resulted in some of the largest HTTP/2 DDoS attack campaigns in recorded history. During that campaign, thousands of hyper-volumetric DDoS attacks targeted Cloudflare. The attacks were multi-million requests per second strong. The average attack rate in that campaign, recorded by Cloudflare, was 30M rps. Approximately 89 of the attacks peaked above 100M rps and the largest one we saw hit 201M rps. Additional coverage was published in our 2023 Q3 DDoS threat report.

HTTP/2 Rapid Reset campaign of hyper-volumetric DDoS attacks in 2023 Q3

Cloudflare's network, its HTTP/2 implementation, and customers using our WAF/CDN services are not affected by this vulnerability. Furthermore, we are not currently aware of any threat actors exploiting this vulnerability in the wild.

Multiple CVEs have been assigned to the various implementations of HTTP/2 that are impacted by this vulnerability. A CERT alert published by Christopher Cullen at Carnegie Mellon University, which was covered by Bleeping Computer, lists the various CVEs:

When analyzing attack statistics, we use our customer’s industry as it is recorded in our systems to determine the most attacked industries. In the first quarter of 2024, the top attacked industry by HTTP DDoS attacks in North America was Marketing and Advertising. In Africa and Europe, the Information Technology and Internet industry was the most attacked. In the Middle East, the most attacked industry was Computer Software. In Asia, the most attacked industry was Gaming and Gambling. In South America, it was the Banking, Financial Services and Insurance (BFSI) industry. Last but not least, in Oceania, was the Telecommunications industry.

Top attacked industries by HTTP DDoS attacks, by region

Globally, the Gaming and Gambling industry was the number one most targeted by HTTP DDoS attacks. Just over seven of every 100 DDoS requests that Cloudflare mitigated were aimed at the Gaming and Gambling industry. In second place, the Information Technology and Internet industry, and in third, Marketing and Advertising.

Top attacked industries by HTTP DDoS attacks

With a share of 75% of all network-layer DDoS attack bytes, the Information Technology and Internet industry was the most targeted by network-layer DDoS attacks. One possible explanation for this large share is that Information Technology and Internet companies may be “super aggregators” of attacks and receive DDoS attacks that are actually targeting their end customers. The Telecommunications industry, the Banking, Financial Services and Insurance (BFSI) industry, the Gaming and Gambling industry and the Computer Software industry accounted for the next three percent.

Top attacked industries by L3/4 DDoS attacks

When normalizing the data by dividing the attack traffic by the total traffic to a given industry, we get a completely different picture. On the HTTP front, Law Firms and Legal Services was the most attacked industry, as over 40% of their traffic was HTTP DDoS attack traffic. The Biotechnology industry came in second with a 20% share of HTTP DDoS attack traffic. In third place, Nonprofits had an HTTP DDoS attack share of 13%. In fourth, Aviation and Aerospace, followed by Transportation, Wholesale, Government Relations, Motion Pictures and Film, Public Policy, and Adult Entertainment to complete the top ten.

Top attacked industries by HTTP DDoS attacks (normalized)

Back to the network layer, when normalized, Information Technology and Internet remained the number one most targeted industry by L3/4 DDoS attacks, as almost a third of their traffic were attacks. In second, Textiles had a 4% attack share. In third, Civil Engineering, followed by Banking Financial Services and Insurance (BFSI), Military, Construction, Medical Devices, Defense and Space, Gaming and Gambling, and lastly Retail to complete the top ten.

Top attacked industries by L3/4 DDoS attacks (normalized)

When analyzing the sources of HTTP DDoS attacks, we look at the source IP address to determine the origination location of those attacks. A country/region that's a large source of attacks indicates that there is most likely a large presence of botnet nodes behind Virtual Private Network (VPN) or proxy endpoints that attackers may use to obfuscate their origin.

In the first quarter of 2024, the United States was the largest source of HTTP DDoS attack traffic, as a fifth of all DDoS attack requests originated from US IP addresses. China came in second, followed by Germany, Indonesia, Brazil, Russia, Iran, Singapore, India, and Argentina.

The top sources of HTTP DDoS attacks

At the network layer, source IP addresses can be spoofed. So, instead of relying on IP addresses to understand the source, we use the location of our data centers where the attack traffic was ingested. We can gain geographical accuracy due to Cloudflare’s large global coverage in over 310 cities around the world.

Using the location of our data centers, we can see that in the first quarter of 2024, over 40% L3/4 DDoS attack traffic was ingested in our US data centers, making the US the largest source of L3/4 attacks. Far behind, in second, Germany at 6%, followed by Brazil, Singapore, Russia, South Korea, Hong Kong, United Kingdom, Netherlands, and Japan.

The top sources of L3/4 DDoS attacks

When normalizing the data by dividing the attack traffic by the total traffic to a given country or region, we get a totally different lineup. Almost a third of the HTTP traffic originating from Gibraltar was DDoS attack traffic, making it the largest source. In second place, Saint Helena, followed by the British Virgin Islands, Libya, Paraguay, Mayotte, Equatorial Guinea, Argentina, and Angola.

The top sources of HTTP DDoS attacks (normalized)

Back to the network layer, normalized, things look rather different as well. Almost 89% of the traffic we ingested in our Zimbabwe-based data centers were L3/4 DDoS attacks. In Paraguay, it was over 56%, followed by Mongolia reaching nearly a 35% attack share. Additional top locations included Moldova, Democratic Republic of the Congo, Ecuador, Djibouti, Azerbaijan, Haiti, and Dominican Republic.

The top sources of L3/4 DDoS attacks (normalized)

When analyzing DDoS attacks against our customers, we use their billing country to determine the “attacked country (or region)”. In the first quarter of 2024, the US was the most attacked by HTTP DDoS attacks. Approximately one out of every 10 DDoS requests that Cloudflare mitigated targeted the US. In second, China, followed by Canada, Vietnam, Indonesia, Singapore, Hong Kong, Taiwan, Cyprus, and Germany.

Top attacked countries and regions by HTTP DDoS attacks

When normalizing the data by dividing the attack traffic by the total traffic to a given country or region, the list changes drastically. Over 63% of HTTP traffic to Nicaragua was DDoS attack traffic, making it the most attacked location. In second, Albania, followed by Jordan, Guinea, San Marino, Georgia, Indonesia, Cambodia, Bangladesh, and Afghanistan.

Top attacked countries and regions by HTTP DDoS attacks (normalized)

On the network layer, China was the number one most attacked location, as 39% of all DDoS bytes that Cloudflare mitigated during the first quarter of 2024 were aimed at Cloudflare’s Chinese customers. Hong Kong came in second place, followed by Taiwan, the United States, and Brazil.

Top attacked countries and regions by L3/4 DDoS attacks

Back to the network layer, when normalized, Hong Kong takes the lead as the most targeted location. L3/4 DDoS attack traffic accounted for over 78% of all Hong Kong-bound traffic. In second place, China with a DDoS share of 75%, followed by Kazakhstan, Thailand, Saint Vincent and the Grenadines, Norway, Taiwan, Turkey, Singapore, and Brazil.

Top attacked countries and regions by L3/4 DDoS attacks (normalized)

Cloudflare's mission is to help build a better Internet, a vision where it remains secure, performant, and accessible to everyone. With four out of every 10 HTTP DDoS attacks lasting over 10 minutes and approximately three out of 10 extending beyond an hour, the challenge is substantial. Yet, whether an attack involves over 100,000 requests per second, as is the case in one out of every 10 attacks, or even exceeds a million requests per second — a rarity seen in only four out of every 1,000 attacks — Cloudflare’s defenses remain impenetrable.

Since pioneering unmetered DDoS Protection in 2017, Cloudflare has steadfastly honored its promise to provide enterprise-grade DDoS protection at no cost to all organizations, ensuring that our advanced technology and robust network architecture do not just fend off attacks but also preserve performance without compromise.