This was a weekend of record-breaking DDoS attacks. Over the weekend, Cloudflare detected and mitigated dozens of hyper-volumetric DDoS attacks. The majority of attacks peaked in the ballpark of 50-70 million requests per second (rps) with the largest exceeding 71 million rps. This is the largest reported HTTP DDoS attack on record, more than 54% higher than the previous reported record of 46M rps in June 2022.

The attacks were HTTP/2-based and targeted websites protected by Cloudflare. They originated from over 30,000 IP addresses. Some of the attacked websites included a popular gaming provider, cryptocurrency companies, hosting providers, and cloud computing platforms. The attacks originated from numerous cloud providers, and we have been working with them to crack down on the botnet.

Record breaking attack: DDoS attack exceeding 71 million requests per second

Over the past year, we’ve seen more attacks originate from cloud computing providers. For this reason, we will be providing service providers that own their own autonomous system a free Botnet threat feed. The feed will provide service providers threat intelligence about their own IP space; attacks originating from within their autonomous system. Service providers that operate their own IP space can now sign up to the early access waiting list.

No. This campaign of attacks arrives less than two weeks after the Killnet DDoS campaign that targeted healthcare websites. Based on the methods and targets, we do not believe that these recent attacks are related to the healthcare campaign. Furthermore, yesterday was the US Super Bowl, and we also do not believe that this attack campaign is related to the game event.

Distributed Denial of Service attacks are cyber attacks that aim to take down Internet properties and make them unavailable for users. These types of cyberattacks can be very efficient against unprotected websites and they can be very inexpensive for the attackers to execute.

An HTTP DDoS attack usually involves a flood of HTTP requests towards the target website. The attacker’s objective is to bombard the website with more requests than it can handle. Given a sufficiently high amount of requests, the website’s server will not be able to process all of the attack requests along with the legitimate user requests. Users will experience this as website-load delays, timeouts, and eventually not being able to connect to their desired websites at all.

Illustration of a DDoS attack

To make attacks larger and more complicated, attackers usually leverage a network of bots — a botnet. The attacker will orchestrate the botnet to bombard the victim’s websites with HTTP requests. A sufficiently large and powerful botnet can generate very large attacks as we’ve seen in this case.

However, building and operating botnets requires a lot of investment and expertise. What is the average Joe to do? Well, an average Joe that wants to launch a DDoS attack against a website doesn’t need to start from scratch. They can hire one of numerous DDoS-as-a-Service platforms for as little as $30 per month. The more you pay, the larger and longer of an attack you’re going to get.

Over the years, it has become easier, cheaper, and more accessible for attackers and attackers-for-hire to launch DDoS attacks. But as easy as it has become for the attackers, we want to make sure that it is even easier - and free - for defenders of organizations of all sizes to protect themselves against DDoS attacks of all types.

Unlike Ransomware attacks, Ransom DDoS attacks don’t require an actual system intrusion or a foothold within the targeted network. Usually Ransomware attacks start once an employee naively clicks an email link that installs and propagates the malware. There’s no need for that with DDoS attacks. They are more like a hit-and-run attack. All a DDoS attacker needs to know is the website’s address and/or IP address.

Yes. The size, sophistication, and frequency of attacks has been increasing over the past months. In our latest DDoS threat report, we saw that the amount of HTTP DDoS attacks increased by 79% year-over-year. Furthermore, the amount of volumetric attacks exceeding 100 Gbps grew by 67% quarter-over-quarter (QoQ), and the number of attacks lasting more than three hours increased by 87% QoQ.

But it doesn’t end there. The audacity of attackers has been increasing as well. In our latest DDoS threat report, we saw that Ransom DDoS attacks steadily increased throughout the year. They peaked in November 2022 where one out of every four surveyed customers reported being subject to Ransom DDoS attacks or threats.

Distribution of Ransom DDoS attacks by month

Yes. If your website, server, or networks are not protected against volumetric DDoS attacks using a cloud service that provides automatic detection and mitigation, we really recommend that you consider it.

Cloudflare customers shouldn’t be worried, but should be aware and prepared. Below is a list of recommended steps to ensure your security posture is optimized.

Cloudflare’s systems have been automatically detecting and mitigating these DDoS attacks.

Cloudflare offers many features and capabilities that you may already have access to but may not be using. So as extra precaution, we recommend taking advantage of these capabilities to improve and optimize your security posture:

1. Ensure all DDoS Managed Rules are set to default settings (High sensitivity level and mitigation actions) for optimal DDoS activation.

2. Cloudflare Enterprise customers that are subscribed to the Advanced DDoS Protection service should consider enabling Adaptive DDoS Protection, which mitigates attacks more intelligently based on your unique traffic patterns.

3. Deploy firewall rules and rate limiting rules to enforce a combined positive and negative security model. Reduce the traffic allowed to your website based on your known usage.

4. Ensure your origin is not exposed to the public Internet (i.e., only enable access to Cloudflare IP addresses). As an extra security precaution, we recommend contacting your hosting provider and requesting new origin server IPs if they have been targeted directly in the past.

5. Customers with access to Managed IP Lists should consider leveraging those lists in firewall rules. Customers with Bot Management should consider leveraging the bot scores within the firewall rules.

6. Enable caching as much as possible to reduce the strain on your origin servers, and when using Workers, avoid overwhelming your origin server with more subrequests than necessary.

7. Enable DDoS alerting to improve your response time.

Defending against DDoS attacks is critical for organizations of all sizes. While attacks may be initiated by humans, they are executed by bots — and to play to win, you must fight bots with bots. Detection and mitigation must be automated as much as possible, because relying solely on humans to mitigate in real time puts defenders at a disadvantage. Cloudflare’s automated systems constantly detect and mitigate DDoS attacks for our customers, so they don’t have to. This automated approach, combined with our wide breadth of security capabilities, lets customers tailor the protection to their needs.

We've been providing unmetered and unlimited DDoS protection for free to all of our customers since 2017, when we pioneered the concept. Cloudflare's mission is to help build a better Internet. A better Internet is one that is more secure, faster, and reliable for everyone - even in the face of DDoS attacks.

We’re pleased to introduce Cloudflare’s free Botnet Threat Feed for Service Providers. This includes all types of service providers, ranging from hosting providers to ISPs and cloud compute providers.

This feed will give service providers threat intelligence on their own IP addresses that have participated in HTTP DDoS attacks as observed from the Cloudflare network — allowing them to crack down on abusers, take down botnet nodes, reduce their abuse-driven costs, and ultimately reduce the amount and force of DDoS attacks across the Internet. We’re giving away this feed for free as part of our mission to help build a better Internet.

Service providers that operate their own IP space can now sign up to the early access waiting list.

Cloudflare provides services to millions of customers ranging from small businesses and individual developers to large enterprises, including 29% of Fortune 1000 companies. Today, about 20% of websites rely directly on Cloudflare’s services. This gives us a unique vantage point on tremendous amounts of DDoS attacks that target our customers.

DDoS attacks, by definition, are distributed. They originate from botnets of many sources — in some cases, from hundreds of thousands to millions of unique IP addresses. In the case of HTTP DDoS attacks, where the victims are flooded with HTTP requests, we know that the source IP addresses that we see are the real ones — they’re not spoofed (altered). We know this because to initiate an HTTP request a connection must be established between the client and server. Therefore, we can reliably identify the sources of the attacks to understand the origins of the attacks.

As we’ve seen in previous attacks, such as the 26 million request per second DDoS attack that was launched by the Mantis botnet, a significant portion originated from service providers such as French-based OVH (Autonomous System Number 16276), the Indonesian Telkomnet (ASN 7713), the US-based iboss (ASN 137922), the Libyan Ajeel (ASN 37284), and others.

Source service providers of a Mantis botnet attack

The service providers are not to blame. Their networks and infrastructure are abused by attackers to launch attacks. But, it can be hard for service providers to identify the abusers. In some cases, we’ve seen as little as one single IP of a service provider participate in a DDoS attack consisting of thousands of bots — all scattered across many service providers. And so, the service providers usually only see a small fraction of the attack traffic leaving their network, and it can be hard to correlate it to malicious activity.

Even more so, in the case of HTTPS DDoS attacks, the service provider would only see encrypted gibberish leaving their network without any possibility to decrypt or understand if it is malicious or legitimate traffic. However, at Cloudflare, we see the entire attack and all of its sources, and can use that to help service providers stop the abusers and attacks.

Leveraging our unique vantage point, we go to great lengths to ensure that our threat intelligence includes actual attackers and not legitimate clients.

Since our previous experience mitigating Mantis botnet attacks, we’ve been working with providers around the world to help them crack down on abusers. We realized the potential and decided to double down on this effort. The result is that each service provider can subscribe to a feed of their own offending IPs, for free, so they can take action and take down the abused systems.

Our mission at Cloudflare is to help build a better Internet — one that is safer, more performant, and more reliable for everyone. We believe that providing this threat intelligence will help us all move in that direction — cracking down on DDoS attackers and taking down malicious botnets.

If you are a service provider and operate your own IP space, you can now sign up to the early access waiting list.

In June 2022, we reported on the largest HTTPS DDoS attack that we’ve ever mitigated — a 26 million request per second attack - the largest attack on record. Our systems automatically detected and mitigated this attack and many more. Since then, we have been tracking this botnet, which we’ve called “Mantis”, and the attacks it has launched against almost a thousand Cloudflare customers.

Cloudflare WAF/CDN customers are protected against HTTP DDoS attacks including Mantis attacks. Please refer to the bottom of this blog for additional guidance on how to best protect your Internet properties against DDoS attacks.

We named the botnet that launched the 26M rps (requests per second) DDoS attack "Mantis" as it is also like the Mantis shrimp, small but very powerful. Mantis shrimps, also known as “thumb-splitters”, are very small; less than 10 cm in length, but their claws are so powerful that they can generate a shock wave with a force of 1,500 Newtons at speeds of 83 km/h from a standing start. Similarly, the Mantis botnet operates a small fleet of approximately 5,000 bots, but with them can generate a massive force — responsible for the largest HTTP DDoS attacks we have ever observed.

Mantis shrimp. Source: Wikipedia.

The Mantis botnet was able to generate the 26M HTTPS requests per second attack using only 5,000 bots. I’ll repeat that: 26 million HTTPS requests per second using only 5,000 bots. That’s an average of 5,200 HTTPS rps per bot. Generating 26M HTTP requests is hard enough to do without the extra overhead of establishing a secure connection, but Mantis did it over HTTPS. HTTPS DDoS attacks are more expensive in terms of required computational resources because of the higher cost of establishing a secure TLS encrypted connection. This stands out and highlights the unique strength behind this botnet.

As opposed to “traditional” botnets that are formed of Internet of Things (IoT) devices such as DVRs, CC cameras, or smoke detectors, Mantis uses hijacked virtual machines and powerful servers. This means that each bot has a lot more computational resources — resulting in this combined thumb-splitting strength.

Mantis is the next evolution of the Meris botnet. The Meris botnet relied on MikroTik devices, but Mantis has branched out to include a variety of VM platforms and supports running various HTTP proxies to launch attacks. The name Mantis was chosen to be similar to "Meris" to reflect its origin, and also because this evolution hits hard and fast. Over the past few weeks, Mantis has been especially active directing its strengths towards almost 1,000 Cloudflare customers.

In our recent DDoS attack trends report, we talked about the increasing number of HTTP DDoS attacks. In the past quarter, HTTP DDoS attacks increased by 72%, and Mantis has surely contributed to that growth. Over the past month, Mantis has launched over 3,000 HTTP DDoS attacks against Cloudflare customers.

When we take a look at Mantis’ targets we can see that the top attacked industry was the Internet & Telecommunications industry with 36% of attack share. In second place, the News, Media & Publishing industry, followed by Gaming and Finance.

When we look at where these companies are located, we can see that over 20% of the DDoS attacks targeted US-based companies, over 15% Russia-based companies, and less than five percent included Turkey, France, Poland, Ukraine, and more.

Cloudflare’s automated DDoS protection system leverages dynamic fingerprinting to detect and mitigate DDoS attacks. The system is exposed to customers as the HTTP DDoS Managed Ruleset. The ruleset is enabled and applying mitigation actions by default, so if you haven’t made any changes, there is no action for you to take — you are protected. You can also review our guides Best Practices: DoS preventive measures and Responding to DDoS attacks for additional tips and recommendations on how to optimize your Cloudflare configurations.

If you are only using Magic Transit or Spectrum but also operate HTTP applications that are not behind Cloudflare, it is recommended to onboard them to Cloudflare’s WAF/CDN service to benefit from L7 protection.

Cloudflare is expanding our WAF’s threat intelligence capabilities by adding four new managed IP lists that can be used as part of any custom firewall rule.

Managed lists are created and maintained by Cloudflare and are built based on threat intelligence feeds collected by analyzing patterns and trends observed across the Internet. Enterprise customers can already use the Open SOCKS Proxy list (launched in March 2021) and today we are adding four new IP lists: “VPNs”, “Botnets, Command and Control Servers”, “Malware” and “Anonymizers”.

You can check what rules are available in your plan by navigating to Manage Account → Configuration → Lists.

Customers can reference these lists when creating a custom firewall rule or in Advanced Rate Limiting. For example, you can choose to block all traffic generated by IPs we categorize as VPNs, or rate limit traffic generated by all Anonymizers. You can simply incorporate managed IP lists in the powerful firewall rule builder. Of course, you can also use your own custom IP list.

Managed IP Lists can be used in WAF rules to manage incoming traffic from these IPs.

These lists are based on Cloudflare-generated threat feeds which are made available as IP lists to be easily consumed in the WAF. Each IP is categorized by combining open source data as well as by analyzing the behavior of each IP leveraging the scale and reach of Cloudflare network. After an IP has been included in one of these feeds, we verify its categorization and feed this information back into our security systems and make it available to our customers in the form of a managed IP list. The content of each list is updated multiple times a day.

In addition to generating IP classifications based on Cloudflare’s internal data, Cloudflare curates and combines several data sources that we believe provide reliable coverage of active security threats with a low false positive rate. In today’s environment, an IP belonging to a cloud provider might today be distributing malware, but tomorrow might be a critical resource for your company.

Some IP address classifications are publicly available, OSINT data, for example Tor exit nodes, and Cloudflare takes care of integrating this into our Anonymizer list so that you don’t have to manage integrating this list into every asset in your network. Other classifications are determined or vetted using a variety of DNS techniques, like lookup, PTR record lookup, and observing passive DNS from Cloudflare’s network.

Our malware and command-and-control focused lists are generated from curated partnerships, and one type of IP address we target when we select partners is data sources that identify security threats that do not have DNS records associated with them.

Our Anonymizer list encompasses several types of services that perform anonymization, including VPNs, open proxies, and Tor nodes. It is a superset of the more narrowly focused VPN list (known commercial VPN nodes), and the Cloudflare Open Proxies list (proxies that relay traffic without requiring authentication).

Using these lists to deploy a preventative security policy for these IPs is great, but what about knowing if an IP that is interacting with your website or application is part of a Botnet or VPN? We first released contextual information for Anonymizers as part of Security Week 2022, but we are now closing the circle by extending this feature to cover all new lists.

As part of Cloudflare's threat intelligence feeds, we are exposing the IP category directly into the dashboard. Say you are investigating requests that were blocked by the WAF and that looked to be probing your application for known software vulnerabilities. If the source IP of these requests is matching with one of our feeds (for example part of a VPN), contextual information will appear directly on the analytics page.

When the source IP of a WAF event matches one of the threat feeds, we provide contextual information directly onto the Cloudflare dashboard.

This information can help you see patterns and decide whether you need to use the managed lists to handle the traffic from these IPs in a particular way, for example by creating a rate limiting rule that reduces the amount of requests these actors can perform over a period of time.

The following table summarizes what plans have access to each one of these features. Any paying plans will have access to the contextual in-dash information, while Enterprise will be able to use different managed lists. Managed lists can be used only on Enterprise zones within an Enterprise account.

* Contact your customer success manager to learn how to get access to these lists.

We are working on enriching our threat feeds even further. In the next months we are going to provide more IP lists, specifically we are looking into lists for cloud providers and Carrier-grade Network Address Translation (CG-NAT).

Last week, Cloudflare automatically detected and mitigated a 26 million request per second DDoS attack — the largest HTTPS DDoS attack on record.

The attack targeted a customer website using Cloudflare’s Free plan. Similar to the previous 15M rps attack, this attack also originated mostly from Cloud Service Providers as opposed to Residential Internet Service Providers, indicating the use of hijacked virtual machines and powerful servers to generate the attack — as opposed to much weaker Internet of Things (IoT) devices.

Over the past year, we’ve witnessed one record-breaking attack after the other. Back in August 2021, we disclosed a 17.2M rps HTTP DDoS attack, and more recently in April, a 15M rps HTTPS DDoS attack. All were automatically detected and mitigated by our HTTP DDoS Managed Ruleset which is powered by our autonomous edge DDoS protection system.

The 26M rps DDoS attack originated from a small but powerful botnet of 5,067 devices. On average, each node generated approximately 5,200 rps at peak. To contrast the size of this botnet, we’ve been tracking another much larger but less powerful botnet of over 730,000 devices. The latter, larger botnet wasn’t able to generate more than one million requests per second, i.e. roughly 1.3 requests per second on average per device. Putting it plainly, this botnet was, on average, 4,000 times stronger due to its use of virtual machines and servers.

Also, worth noting that this attack was over HTTPS. HTTPS DDoS attacks are more expensive in terms of required computational resources because of the higher cost of establishing a secure TLS encrypted connection. Therefore, it costs the attacker more to launch the attack, and for the victim to mitigate it. We’ve seen very large attacks in the past over (unencrypted) HTTP, but this attack stands out because of the resources it required at its scale.

Within less than 30 seconds, this botnet generated more than 212 million HTTPS requests from over 1,500 networks in 121 countries. The top countries were Indonesia, the United States, Brazil and Russia. About 3% of the attack came through Tor nodes.

The top source networks were the French-based OVH (Autonomous System Number 16276), the Indonesian Telkomnet (ASN 7713), the US-based iboss (ASN 137922) and the Libyan Ajeel (ASN 37284).

It’s important to understand the attack landscape when thinking about DDoS protection. When looking at our recent DDoS Trends report, we can see that most of the attacks are small, e.g. cyber vandalism. However, even small attacks can severely impact unprotected Internet properties. On the other hand, large attacks are growing in size and frequency — but remain short and rapid. Attackers concentrate their botnet’s power to try and wreak havoc with a single quick knockout blow — trying to avoid detection.

DDoS attacks might be initiated by humans, but they are generated by machines. By the time humans can respond to the attack, it may be over. And even if the attack was quick, the network and application failure events can extend long after the attack is over — costing you revenue and reputation. For this reason, it is recommended to protect your Internet properties with an automated always-on protection service that does not rely on humans to detect and mitigate attacks.

At Cloudflare, everything we do is guided by our mission to help build a better Internet. The DDoS team’s vision is derived from this mission: our goal is to make the impact of DDoS attacks a thing of the past. The level of protection that we offer is unmetered and unlimited — It is not bounded by the size of the attack, the number of the attacks, or the duration of the attacks. This is especially important these days because as we’ve recently seen, attacks are getting larger and more frequent.

Not using Cloudflare yet? Start now with our Free and Pro plans to protect your websites, or contact us for comprehensive DDoS protection for your entire network using Magic Transit.

Earlier this week, Cloudflare automatically detected and mitigated a DDoS attack that peaked just below 2 Tbps — the largest we’ve seen to date. This was a multi-vector attack combining DNS amplification attacks and UDP floods. The entire attack lasted just one minute. The attack was launched from approximately 15,000 bots running a variant of the original Mirai code on IoT devices and unpatched GitLab instances.

DDoS attack peaking just below 2 Tbps‌‌

Last quarter, we saw multiple terabit-strong DDoS attacks and this attack continues this trend of increased attack intensity. Another key finding from our Q3 DDoS Trends report was that network-layer DDoS attacks actually increased by 44% quarter-over-quarter. While the fourth quarter is not over yet, we have, again, seen multiple terabit-strong attacks that targeted Cloudflare customers.

DDoS attacks peaking at 1-1.4 Tbps

To begin with, our systems constantly analyze traffic samples “out-of-path” which allows us to asynchronously detect DDoS attacks without causing latency or impacting performance. Once the attack traffic was detected (within sub-seconds), our systems generated a real-time signature that surgically matched against the attack patterns to mitigate the attack without impacting legitimate traffic.

Once generated, the fingerprint is propagated as an ephemeral mitigation rule to the most optimal location in the Cloudflare edge for cost-efficient mitigation. In this specific case, as with most L3/4 DDoS attacks, the rule was pushed in-line into the Linux kernel eXpress Data Path (XDP) to drop the attack packet at wirespeed.

A conceptual diagram of Cloudflare’s DDoS protection systems

Read more about Cloudflare’s DDoS Protection systems.

Cloudflare’s mission is to help build a better Internet — one that is secure, faster, and more reliable for everyone. The DDoS team’s vision is derived from this mission: our goal is to make the impact of DDoS attacks a thing of the past. Whether it's the Meris botnet that launched some of the largest HTTP DDoS attacks on record, the recent attacks on VoIP providers or this Mirai-variant that’s DDoSing Internet properties, Cloudflare’s network automatically detects and mitigates DDoS attacks. Cloudflare provides a secure, reliable, performant, and customizable platform for Internet properties of all types.

For more information about Cloudflare’s DDoS protection, reach out to us or have a go with a hands-on evaluation of Cloudflare’s Free plan.

Earlier this summer, Cloudflare’s autonomous edge DDoS protection systems automatically detected and mitigated a 17.2 million request-per-second (rps) DDoS attack, an attack almost three times larger than any previous one that we're aware of. For perspective on how large this attack was: Cloudflare serves over 25 million HTTP requests per second on average. This refers to the average rate of legitimate traffic in 2021 Q2. So peaking at 17.2 million rps, this attack reached 68% of our Q2 average rps rate of legitimate HTTP traffic.

Comparison graph of Cloudflare’s average request per second rate versus the DDoS attack

This attack, along with the additional attacks provided in the next sections, were automatically detected and mitigated by our autonomous edge DDoS protection systems. The system is powered by our very own denial of service daemon (dosd). Dosd is a home-grown software-defined daemon. A unique dosd instance runs in every server in each one of our data centers around the world. Each dosd instance independently analyzes traffic samples out-of-path. Analyzing traffic out-of-path allows us to scan asynchronously for DDoS attacks without causing latency and impacting performance. DDoS findings are also shared between the various dosd instances within a data center, as a form of proactive threat intelligence sharing.

Once an attack is detected, our systems generate a mitigation rule with a real-time signature that matches the attack patterns. The rule is propagated to the most optimal location in the tech stack. As an example, a volumetric HTTP DDoS attack may be blocked at L4 inside the Linux iptables firewall instead of at L7 inside the L7 reverse proxy which runs in the user space. Mitigating lower in the stack, e.g. dropping the packets at L4 instead of responding with a 403 error page in L7, is more cost-efficient. It reduces our edge CPU consumption and intra-data center bandwidth utilization — thus helping us mitigate large attacks at scale without impacting performance.

This autonomous approach, along with our network’s global scale and reliability, allow us to mitigate attacks that reach 68% of our average per-second-rate, and higher, without requiring any manual mitigation by Cloudflare personnel, nor causing any performance degradation.

This attack was launched by a powerful botnet, targeting a Cloudflare customer in the financial industry. Within seconds, the botnet bombarded the Cloudflare edge with over 330 million attack requests.

Graph of 17.2M rps attack

The attack traffic originated from more than 20,000 bots in 125 countries around the world. Based on the bots’ source IP addresses, almost 15% of the attack originated from Indonesia and another 17% from India and Brazil combined. Indicating that there may be many malware infected devices in those countries.

Distribution of the attack sources by top countries

This 17.2 million rps attack is the largest HTTP DDoS attack that Cloudflare has ever seen to date and almost three times the size of any other reported HTTP DDoS attack. This specific botnet, however, has been seen at least twice over the past few weeks. Just last week it also targeted a different Cloudflare customer, a hosting provider, with an HTTP DDoS attack that peaked just below 8 million rps.

Graph of 8M rps attack

Two weeks before, a Mirai-variant botnet launched over a dozen UDP and TCP based DDoS attacks that peaked multiple times above 1 Tbps, with a max peak of approximately 1.2 Tbps. And while the first HTTP attacks targeted Cloudflare customers on the WAF/CDN service, the 1+ Tbps network-layer attacks targeted Cloudflare customers on the Magic Transit and Spectrum services. One of these targets was a major APAC-based Internet services, telecommunications and hosting provider. The other was a gaming company. In all cases, the attacks were automatically detected and mitigated without human intervention.

Graph of Mirai botnet attack peaking at 1.2 Tbps

The Mirai botnet started with roughly 30K bots and slowly shrinked to approximately 28K. However, despite losing bots from its fleet, the botnet was still able to generate impressive volumes of attack traffic for short periods. In some cases, each burst lasted only a few seconds.

These attacks join the increase in Mirai-based DDoS attacks that we’ve observed on our network over the past weeks. In July alone, L3/4 Mirai attacks increased by 88% and L7 attacks by 9%. Additionally, based on the current August per-day average of the Mirai attacks, we can expect L7 Mirai DDoS attacks and other similar botnet attacks to increase by 185% and L3/4 attacks by 71% by the end of the month.

Graph of change in Mirai based DDoS attacks by month

Mirai, which means ‘future’ in Japanese, is a codename for malware that was first discovered in 2016 by MalwareMustDie, a non-profit security research workgroup. The malware spreads by infecting Linux-operated devices such as security cameras and routers. It then self-propagates by searching for open Telnet ports 23 and 2323. Once found, it then attempts to gain access to vulnerable devices by brute forcing known credentials such as factory default usernames and passwords. Later variants of Mirai also took advantage of zero-day exploits in routers and other devices. Once infected, the devices will monitor a Command & Control (C2) server for instructions on which target to attack.

Diagram of Botnet operator controlling the botnet to attack websites

While the majority of attacks are small and short, we continue to see these types of volumetric attacks emerging more often. It’s important to note that these volumetric short burst attacks can be especially dangerous for legacy DDoS protection systems or organizations without active, always-on cloud-based protection.

Furthermore, while the short duration may say something about the botnet’s capability to deliver sustained levels of traffic over time, it can be challenging or impossible for humans to react to it in time. In such cases, the attack is over before a security engineer even has time to analyze the traffic or activate their stand-by DDoS protection system. These types of attacks highlight the need for automated, always-on protection.

1. Onboard to Cloudflare to protect your Internet properties.

2. DDoS is enabled out of the box, and you can also customize the protection settings.

3. Follow our preventive best practices, to ensure that both your Cloudflare settings and your origin server settings are optimized. As an example, make sure that you allow only traffic from Cloudflare’s IP range. Ideally, ask your upstream Internet Service Provider (ISP) to apply an access control list (ACL), otherwise, attackers may target your servers’ IP addresses directly and bypass your protection.

1. Change the default username and password of any device that is connected to the Internet such as smart cameras and routers. This will reduce the risk that malware such as Mirai can gain access to your router and IoT devices.

2. Protect your home against malware with Cloudflare for Families. Cloudflare for Families is a free service that automatically blocks traffic from your home to malicious websites and malware communication.