Welcome to the first DDoS threat report of 2023. DDoS attacks, or distributed denial-of-service attacks, are a type of cyber attack that aim to overwhelm Internet services such as websites with more traffic than they can handle, in order to disrupt them and make them unavailable to legitimate users. In this report, we cover the latest insights and trends about the DDoS attack landscape as we observed across our global network.

Kicking off 2023 with a bang

Threat actors kicked off 2023 with a bang. The start of the year was characterized by a series of hacktivist campaigns against Western targets including banking, airports, healthcare and universities — mainly by the pro-Russian Telegram-organized groups Killnet and more recently by AnonymousSudan.

While Killnet-led and AnonymousSudan-led cyberattacks stole the spotlight, we haven’t witnessed any novel or exceedingly large attacks by them.

Hyper-volumetric attacks

We did see, however, an increase of hyper-volumetric DDoS attacks launched by other threat actors — with the largest one peaking above 71 million requests per second (rps) — exceeding Google’s previous world record of 46M rps by 55%.

Back to Killnet and AnonymousSudan, while no noteworthy attacks were reported, we shouldn't underestimate the potential risks. Unprotected Internet properties can still be, and have been, taken down by Killnet-led or AnonymousSudan-led cyber campaigns. Organizations should take proactive defensive measures to reduce the risks.

Business as usual for South American Telco targeted by terabit-strong attacks thanks to Cloudflare

Another large attack we saw in Q1 was a 1.3 Tbps (terabits per second) DDoS attack that targeted a South American Telecommunications provider. The attack lasted only a minute. It was a multi-vector attack involving DNS and UDP attack traffic. The attack was part of a broader campaign which included multiple Terbit-strong attacks originating from a 20,000-strong Mirai-variant botnet. Most of the attack traffic originated from the US, Brazil, Japan, Hong Kong, and India. Cloudflare systems automatically detected and mitigated it without any impact to the customer’s networks.

High-performance botnets

Hyper-volumetric attacks leverage a new generation of botnets that are comprised of Virtual Private Servers (VPS) instead of Internet of Things (IoT) devices.

Historically, large botnets relied on exploitable IoT devices such as smart security cameras to orchestrate their attacks. Despite the limited throughput of each IoT device, together — usually numbering in the hundreds of thousands or millions — they generated enough traffic to disrupt their targets.

The new generation of botnets uses a fraction of the amount of devices, but each device is substantially stronger. Cloud computing providers offer virtual private servers to allow start ups and businesses to create performant applications. The downside is that it also allows attackers to create high-performance botnets that can be as much as 5,000x stronger. Attackers gain access to virtual private servers by compromising unpatched servers and hacking into management consoles using leaked API credentials.

Cloudflare has been working with key cloud computing providers to crack down on these VPS-based botnets. Substantial portions of such botnets have been disabled thanks to the cloud computing providers’ rapid response and diligence. Since then, we have yet to see additional hyper-volumetric attacks — a testament to the fruitful collaboration.

We have excellent collaboration with the cyber-security community to take down botnets once we detect such large-scale attacks, but we want to make this process even simpler and more automated.

We invite Cloud computing providers, hosting providers and general service providers to sign up for Cloudflare’s free Botnet Threat Feed to gain visibility on attacks launching from within their networks — and help us dismantle botnets.

Key highlights from this quarter

1. In Q1, 16% of surveyed customers reported a Ransom DDoS attack — remains steady compared to the previous quarter but represents a 60% increase YoY.
2. Non-profit organizations and Broadcast Media were two of the most targeted industries. Finland was the largest source of HTTP DDoS attacks in terms of percentage of attack traffic, and the main target of network-layer DDoS attacks. Israel was the top most attacked country worldwide by HTTP DDoS attacks.
3. Large scale volumetric DDoS attacks — attacks above 100 Gbps — increased by 6% QoQ. DNS-based attacks became the most popular vector. Similarly, we observed surges in SPSS-bas in ed DDoS attacks, DNS amplification attacks, and GRE-based DDoS attacks.

Ransom DDoS attacks

Often, DDoS attacks are carried out to extort ransom payments. We continue to survey Cloudflare customers and track the ratio of DDoS events where the target received a ransom note. This number has been steadily rising through 2022 and currently stands at 16% - the same as in Q4 2022.

As opposed to Ransomware attacks, where usually the victim is tricked into downloading a file or clicking on an email link that encrypts and locks their computer files until they pay a ransom fee, Ransom DDoS attacks can be much easier for attackers to execute. Ransom DDoS attacks don't require tricking the victim into opening an email or clicking a link, nor do they require a network intrusion or a foothold into the corporate assets.

In a Ransom DDoS attack, the attacker doesn’t need access to the victim’s computer but rather just needs to bombard them with a sufficiently large amount of traffic to take down their websites, DNS servers, and any other type of Internet-connected property to make it unavailable or with poor performance to users. The attacker will demand a ransom payment, usually in the form of Bitcoin, to stop and/or avoid further attacks.

The months of January 2023 and March 2023 were the second highest in terms of Ransom DDoS activity as reported by our users. The highest month thus far remains November 2022 — the month of Black Friday, Thanksgiving, and Singles Day in China — a lucrative month for threat actors.

Who and what are being attacked?

Top targeted countries

Perhaps related to the judicial reform and opposing protests, in Q1, Israel jumps to the first place as the country targeted by the most HTTP DDoS attack traffic — even above the United States of America. This is an astonishing figure. Just short of a single percent of all HTTP traffic that Cloudflare processed in the first quarter of the year, was part of HTTP DDoS attacks that targeted Israeli websites. Following closely behind Israel are the US, Canada, and Turkey.

In terms of the percentage of attack traffic compared to all traffic to a given country, Slovenia and Georgia came at the top. Approximately 20% of all traffic to Slovenian and Georgian websites were HTTP DDoS attacks. Next in line were the small Caribbean dual-island nation, Saint Kitts and Nevis, and Turkey. While Israel was the top in the previous graph, here it has found its placement as the ninth most attacked country — above Russia. Still high compared to previous quarters.

Looking at the total amount of network-layer DDoS attack traffic, China came in first place. Almost 18% of all network-layer DDoS attack traffic came from China. Closely in second, Singapore came in second place with a 17% share. The US came in third, followed by Finland.

When we normalize attacks to a country by all traffic to that country, Finland jumps to the first place, perhaps due to its newly approved NATO membership. Nearly 83% of all traffic to Finland was network-layer attack traffic. China followed closely with 68% and Singapore again with 49%.

Top targeted industries

In terms of overall bandwidth, globally, Internet companies saw the largest amount of HTTP DDoS attack traffic. Afterwards, it was the Marketing and Advertising industry, Computer Software industry, Gaming / Gambling and Telecommunications.

By percentage of attack traffic out of total traffic to an industry, Non-profits were the most targeted in the first quarter of the year, followed by Accounting firms. Despite the uptick of attacks on healthcare, it didn’t make it into the top ten. Also up there in the top were Chemicals, Government, and Energy Utilities & Waste industries. Looking at the US, almost 2% of all traffic to US Federal websites were part of DDoS attacks.

On a regional scale, the Gaming & Gambling industry was the most targeted in Asia, Europe, and the Middle East. In South and Central America, the Banking, Financial Services and Insurance (BFSI) industry was the most targeted. In North America it was the Marketing & Advertising industry followed by Telecommunications — which was also the most attacked industry in Africa. Last by not least, in Oceania, the Health, Wellness and Fitness industry was the most targeted by HTTP DDoS attacks.

Diving lower in the OSI stack, based on the total volume of L3/4 attack traffic, the most targeted industries were Information Technology and Services, Gaming / Gambling, and Telecommunications.

When comparing the attack traffic to the total traffic per industry, we see a different picture. Almost every second byte transmitted to Broadcast Media companies was L3/4 DDoS attack traffic.

Where attacks are coming from

Top source countries

In the first quarter of 2023, Finland was the largest source of HTTP DDoS attacks in terms of the percentage of attack traffic out of all traffic per country. Closely after Finland, the British Virgin Islands came in second place, followed by Libya and Barbados.

In terms of absolute volumes, the most HTTP DDoS attack traffic came from US IP addresses. China came in second, followed by Germany, Indonesia, Brazil, and Finland.

On the L3/4 side of things, Vietnam was the largest source of L3/4 DDoS attack traffic. Almost a third of all L3/4 traffic we ingested in our Vietnam data centers was attack traffic. Following Vietnam were Paraguay, Moldova, and Jamaica.

What attack types and sizes we see

Attack size and duration

When looking at the types of attacks that are launched against our customers and our own network and applications, we can see that the majority of attacks are short and small; 86% of network-layer DDoS attacks end within 10 minutes, and 91% of attacks never exceed 500 Mbps.

Only one out of every fifty attacks ever exceeds 10 Gbps, and only one out of every thousand attacks exceeds 100 Gbps.

Having said that, larger attacks are slowly increasing in quantity and frequency. Last quarter, attacks exceeding 100 Gbps saw a 67% increase QoQ in their quantity. This quarter, the growth has slowed down a bit to 6%, but it's still growing. In fact, there was an increase in all volumetric attacks excluding the ‘small’ bucket where the majority fall into — as visualized in the graph below. The largest growth was in the 10-100 Gbps range; an 89% increase QoQ.

Attack vectors

This quarter we saw a tectonic shift. With a 22% share, SYN floods scooched to the second place, making DNS-based DDoS attacks the most popular attack vector (30%). Almost a third of all L3/4 DDoS attacks were DNS-based; either DNS floods or DNS amplification/reflection attacks. Not far behind, UDP-based attacks came in third with a 21% share.

Emerging threats

Every quarter we see the reemergence of old and sometimes even ancient attack vectors. What this tells us is that even decade-old vulnerabilities are still being exploited to launch attacks. Threat actors are recycling and reusing old methods — perhaps hoping that organizations have dropped those protections against older methods.

In the first quarter of 2023, there was a massive surge in SPSS-based DDoS attacks, DNS amplification attacks and GRE-based DDoS attacks.

SPSS-based DDoS attacks increased by 1,565% QoQ

The Statistical Product and Service Solutions (SPSS) is an IBM-developed software suite for use cases such as data management, business intelligence, and criminal investigation. The Sentinel RMS License Manager server is used to manage licensing for software products such as the IBM SPSS system. Back in 2021, two vulnerabilities (CVE-2021-22713 and CVE-2021-38153) were identified in the Sentinel RMS License Manager server which can be used to launch reflection DDoS attacks. Attackers can send large amounts of specially crafted license requests to the server, causing it to generate a response that is much larger than the original request. This response is sent back to the victim's IP address, effectively amplifying the size of the attack and overwhelming the victim's network with traffic. This type of attack is known as a reflection DDoS attack, and it can cause significant disruption to the availability of software products that rely on the Sentinel RMS License Manager, such as IBM SPSS Statistics. Applying the available patches to the license manager is essential to prevent these vulnerabilities from being exploited and to protect against reflection DDoS attacks.

DNS amplification DDoS attacks increased by 958% QoQ

DNS amplification attacks are a type of DDoS attack that involves exploiting vulnerabilities in the Domain Name System (DNS) infrastructure to generate large amounts of traffic directed at a victim's network. Attackers send DNS requests to open DNS resolvers that have been misconfigured to allow recursive queries from any source, and use these requests to generate responses that are much larger than the original query. The attackers then spoof the victim's IP address, causing the large responses to be directed at the victim's network, overwhelming it with traffic and causing a denial of service. The challenge of mitigating DNS amplification attacks is that the attack traffic can be difficult to distinguish from legitimate traffic, making it difficult to block at the network level. To mitigate DNS amplification attacks, organizations can take steps such as properly configuring DNS resolvers, implementing rate-limiting techniques, and using traffic filtering tools to block traffic from known attack sources.

GRE-based DDoS attacks increased by 835% QoQ

GRE-based DDoS attacks involve using the Generic Routing Encapsulation (GRE) protocol to flood a victim's network with large amounts of traffic. Attackers create multiple GRE tunnels between compromised hosts to send traffic to the victim's network. These attacks are difficult to detect and filter, as the traffic appears as legitimate traffic on the victim's network. Attackers can also use source IP address spoofing to make it appear that the traffic is coming from legitimate sources, making it difficult to block at the network level. GRE-based DDoS attacks pose several risks to targeted organizations, including downtime, disruption of business operations, and potential data theft or network infiltration. Mitigating these attacks requires the use of advanced traffic filtering tools that can detect and block attack traffic based on its characteristics, as well as techniques such as rate limiting and source IP address filtering to block traffic from known attack sources.

The DDoS threat landscape

In recent months, there has been an increase in longer and larger DDoS attacks across various industries, with volumetric attacks being particularly prominent. Non-profit and Broadcast Media companies were some of the top targeted industries. DNS DDoS attacks also became increasingly prevalent.

As DDoS attacks are typically carried out by bots, automated detection and mitigation are crucial for effective defense. Cloudflare's automated systems provide constant protection against DDoS attacks for our customers, allowing them to focus on other aspects of their business. We believe that DDoS protection should be easily accessible to organizations of all sizes, and have been offering free and unlimited protection since 2017.

At Cloudflare, our mission is to help build a better Internet — one that is more secure and faster Internet for all.

We invite you to join our DDoS Trends Webinar to learn more about emerging threats and effective defense strategies.

A note about methodologies

How we calculate Ransom DDoS attack insights
Cloudflare’s systems constantly analyze traffic and automatically apply mitigation when DDoS attacks are detected. Each attacked customer is prompted with an automated survey to help us better understand the nature of the attack and the success of the mitigation. For over two years, Cloudflare has been surveying attacked customers. One of the questions in the survey asks the respondents if they received a threat or a ransom note. Over the past two years, on average, we collected 164 responses per quarter. The responses of this survey are used to calculate the percentage of Ransom DDoS attacks.

How we calculate geographical and industry insights
Source country
At the application-layer, we use the attacking IP addresses to understand the origin country of the attacks. That is because at that layer, IP addresses cannot be spoofed (i.e., altered). However, at the network layer, source IP addresses can be spoofed. So, instead of relying on IP addresses to understand the source, we instead use the location of our data centers where the attack packets were ingested. We’re able to get geographical accuracy due to our large global coverage in over 285 locations around the world.

Target country
For both application-layer and network-layer DDoS attacks, we group attacks and traffic by our customers’ billing country. This lets us understand which countries are subject to more attacks.

Target industry
For both application-layer and network-layer DDoS attacks, we group attacks and traffic by our customers’ industry according to our customer relations management system. This lets us understand which industries are subject to more attacks.

Total volume vs. percentage
For both source and target insights, we look at the total volume of attack traffic compared to all traffic as one data point. Additionally, we also look at the percentage of attack traffic towards or from a specific country, to a specific country or to a specific industry. This gives us an “attack activity rate” for a given country/industry which is normalized by their total traffic levels. This helps us remove biases of a country or industry that normally receives a lot of traffic and therefore a lot of attack traffic as well.

How we calculate attack characteristics
To calculate the attack size, duration, attack vectors and emerging threats, we bucket attacks and then provide the share of each bucket out of the total amount for each dimension.

General disclaimer and clarification
When we describe ‘top countries’ as the source or target of attacks, it does not necessarily mean that that country was attacked as a country, but rather that organizations that use that country as their billing country were targeted by attacks. Similarly, attacks originating from a country does not mean that that country launched the attacks, but rather that the attack was launched from IP addresses that have been mapped to that country. Threat actors operate global botnets with nodes all over the world, and in many cases also use Virtual Private Networks and proxies to obfuscate their true location. So if anything, the source country could indicate the presence of exit nodes or botnet nodes within that country.

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