KEMTLS: Post-quantum TLS without signatures

The Transport Layer Security protocol (TLS), which secures most Internet connections, has mainly been a protocol consisting of a key exchange authenticated by digital signatures used to encrypt data at transport^[1]. Even though it has undergone major changes since 1994, when SSL 1.0 was introduced by Netscape, its main mechanism has remained the same. The key exchange was first based on RSA, and later on traditional Diffie-Hellman (DH) and Elliptic-curve Diffie-Hellman (ECDH). The signatures used for authentication have almost always been RSA-based, though in recent years other kinds of signatures have been adopted, mainly ECDSA and Ed25519. This recent change to elliptic curve cryptography in both at the key exchange and at the signature level has resulted in considerable speed and bandwidth benefits in comparison to traditional Diffie-Hellman and RSA.

TLS is the main protocol that protects the connections we use everyday. It’s everywhere: we use it when we buy products online, when we register for a newsletter — when we access any kind of website, IoT device, API for mobile apps and more, really. But with the imminent threat of the arrival of quantum computers (a threat that seems to be getting closer and closer), we need Continue reading

Holistic web protection: industry recognition for a prolific 2020

I love building products that solve real problems for our customers. These days I don’t get to do so as much directly with our Engineering teams. Instead, about half my time is spent with customers listening to and learning from their security challenges, while the other half of my time is spent with other Cloudflare Product Managers (PMs) helping them solve these customer challenges as simply and elegantly as possible. While I miss the deeply technical engineering discussions, I am proud to have the opportunity to look back every year on all that we’ve shipped across our application security teams.

Taking the time to reflect on what we’ve delivered also helps to reinforce my belief in the Cloudflare approach to shipping product: release early, stay close to customers for feedback, and iterate quickly to deliver incremental value. To borrow a term from the investment world, this approach brings the benefits of compounded returns to our customers: we put new products that solve real-world problems into their hands as quickly as possible, and then reinvest the proceeds of our shared learnings immediately back into the product.

It is these sustained investments that allow us to release a flurry of small improvements Continue reading

Soar: Simulation for Observability, reliAbility, and secuRity

Serving more than approximately 25 million Internet properties is not an easy thing, and neither is serving 20 million requests per second on average. At Cloudflare, we achieve this by running a homogeneous edge environment: almost every Cloudflare server runs all Cloudflare products.

As we offer more and more products and enjoy the benefit of horizontal scalability, our edge stack continues to grow in complexity. Originally, we only operated at the application layer with our CDN service and DoS protection. Then we launched transport layer products, such as Spectrum and Argo. Now we have further expanded our footprint into the IP layer and physical link with Magic Transit. They all run on every machine we have. The work of our engineers enables our products to evolve at a fast pace, and to serve our customers better.

However, such software complexity presents a sheer challenge to operation: the more changes you make, the more likely it is that something is going to break. Continue reading

A Name Resolver for the Distributed Web

The Domain Name System (DNS) matches names to resources. Instead of typing 104.18.26.46 to access the Cloudflare Blog, you type blog.cloudflare.com and, using DNS, the domain name resolves to 104.18.26.46, the Cloudflare Blog IP address.

Similarly, distributed systems such as Ethereum and IPFS rely on a naming system to be usable. DNS could be used, but its resolvers’ attributes run contrary to properties valued in distributed Web (dWeb) systems. Namely, dWeb resolvers ideally provide (i) locally verifiable data, (ii) built-in history, and (iii) have no single trust anchor.

At Cloudflare Research, we have been exploring alternative ways to resolve queries to responses that align with these attributes. We are proud to announce a new resolver for the Distributed Web, where IPFS content indexed by the Ethereum Name Service (ENS) can be accessed.

To discover how it has been built, and how you can use it today, read on.

Welcome to the Distributed Web

IPFS and its addressing system

The InterPlanetary FileSystem (IPFS) is a peer-to-peer network for storing content on a distributed file system. It is composed of a set of computers called nodes that store and relay content using a common Continue reading

Cloudflare Radar’s 2020 Year In Review

Throughout 2020, we tracked changing Internet trends as the SARS-Cov-2 pandemic forced us all to change the way we were living, working, exercising and learning. In early April, we created a dedicated website https://builtforthis.net/ that showed some of the ways in which Internet use had changed, suddenly, because of the crisis.

On that website, we showed how traffic patterns had changed; for example, where people accessed the Internet from, how usage had jumped up dramatically, and how Internet attacks continued unabated and ultimately increased.

Today we are launching a dedicated Year In Review page with interactive maps and charts you can use to explore what changed on the Internet in 2020. Year In Review is part of Cloudflare Radar. We launched Radar in September 2020 to give anyone access to Internet use and abuse trends that Cloudflare normally had reserved only for employees.

Where people accessed the Internet

To get a sense for the Year In Review, let’s zoom in on London (you can do the same with any city from a long list of locations that we’ve analyzed). Here’s a map showing the change in Internet use comparing April (post-lockdown) and February (pre-lockdown). This map compares working hours Continue reading

Untangling Compliance: Working Toward a Global Framework

As part of Cloudflare’s recent Privacy Week we hosted a series of fireside chats on security, privacy, and compliance. Many of these conversations touched on the intricate legal debate being held in Europe around data sovereignty. Here are some of the highlights.

To learn more about the solutions Cloudflare launched to help businesses navigate their compliance needs — including the new data localization suite — see our recent blog post here.

Prof. Dr. Wilfried Bernhardt
Honorary professor -- University of Leipzig,
Attorney, CEO Bernhardt IT Management Consulting GmbH

We have to agree to go down a common road, a common path. And this common path can really only consist of saying: let's sit down together again. I'm talking about the European Commission and, above all, the new administration in the United States. We are all waiting for them expectantly.

And then we look at what our common fundamental values are and see if we don’t simply come together better than we have in the past. After all, our fundamental values are the same: human rights, democracy, the rule of law. You have to concede that there are some differences in understanding when it comes to interpreting what privacy means — Continue reading

Meet The Workers Team Over Discord

The Cloudflare Workers team is excited to announce the opening of our Discord channel! You can join right away by going here.

Through our Discord channel, you can now connect with the team to ask questions, show off what you’re building, and discuss the platform with other developers.

Sometimes you just need to talk to another human being. Our developer docs will always be the source of truth on the mechanics of Workers, but we want to provide quicker help if you need it.

Growing The Workers Community

Over the past three years, Cloudflare Workers evolved from an initial sandbox for enterprise customers writing edge code to a developer platform for creating new applications and systems.

“We bet our whole business on Workers and it paid off big time,” said Hamlet Batista, CEO of RankSense, a SEO automation platform. “We've been saving a lot of money on infrastructure costs and DevOps resources we no longer need.”

Our team is constantly surprised by the palette of use cases from those developing on Workers. For example, a developer in Belgium created a static Workers site that teaches an online tutorial in three different languages on how to make your own face Continue reading

Ransom DDoS attacks target a Fortune Global 500 company

In late 2020, a major Fortune Global 500 company was targeted by a Ransom DDoS (RDDoS) attack by a group claiming to be the Lazarus Group. Cloudflare quickly onboarded them to the Magic Transit service and protected them against the lingering threat. This extortion attempt was part of wider ransom campaigns that have been unfolding throughout the year, targeting thousands of organizations around the world. Extortionists are threatening organizations with crippling DDoS attacks if they do not pay a ransom.

Throughout 2020, Cloudflare onboarded and protected many organizations with Magic Transit, Cloudflare’s DDoS protection service for critical network infrastructure, the WAF service for HTTP applications, and the Spectrum service for TCP/UDP based applications -- ensuring their business’s availability and continuity.

Unwinding the attack timeline

I spoke with Daniel (a pseudonym) and his team, who work at the Incident Response and Forensics team at the aforementioned company. I wanted to learn about their experience, and share it with our readers so they could learn how to better prepare for such an event. The company has requested to stay anonymous and so some details have been omitted to ensure that. In this blog post, I will refer to them as X.

Initially, Continue reading

Internet traffic disruption caused by the Christmas Day bombing in Nashville

On Christmas Day 2020, an apparent suicide bomb exploded in Nashville, TN. The explosion happened outside an AT&T network building on Second Avenue in Nashville at 1230 UTC. Damage to the AT&T building and its power supply and generators quickly caused an outage for telephone and Internet service for local people. These outages continued for two days.

Looking at traffic flow data for AT&T in the Nashville area to Cloudflare we can see that services continued operating (on battery power according to reports) for over five hours after the explosion, but at 1748 UTC we saw a dramatic drop in traffic. 1748 UTC is close to noon in Nashville when reports indicate that people lost phone and Internet service.

We saw traffic from Nashville via AT&T start to recover over a 45 minute period on December 27 at 1822 UTC making the total outage 2 days and 34 minutes.

Traffic flows continue to be normal and no further disruption has been seen.

Using One Cron Parser Everywhere With Rust and Saffron

As part of the development for Cron Triggers on Cloudflare Workers, we had an interesting problem to tackle relating to parsers and the cron expression format. Cron expressions are the format used to write schedules in Cron Triggers, and extensions for cron expressions are everywhere. They vary between parsers and platforms as well, and aren’t standardized by a governing body, which means most parsers out there support many different feature sets, which isn’t good if you’d like something off the shelf that just works.

It can be tough to find the right parser for each part of the Cron Triggers stack, when its user interface, API, and edge service are all written in different languages. On top of that, it isn’t practical to reinvent the wheel multiple times by writing the same parser in different languages and make sure they all match perfectly. So you’re likely stuck with a less-than-perfect solution.

However, in the end, because we wrote our backend service in Rust, it took much less effort to solve this problem. Rust has a great ecosystem for working across multiple languages, which allows us to write a parser once and pull it from the backend to the frontend and Continue reading

Holiday Season Update from Lisbon

It's the end of the year, so we thought it would be a great time to give you an update on how we're doing and what we're planning for 2021. If you're reading this, you know we like to share everything we do at Cloudflare, including how the organization is evolving.

In July, John Graham-Cumming wrote a blog post entitled Cloudflare's first year in Lisbon. and showed how we went from an announcement, just a few months before, to an entirely bootstrapped and fully functional office. At the time, despite a ramping pandemic, the team was already hard at work doing a fantastic job scaling up and solidifying our presence here.

A few weeks later, in August, I proudly joined the team.

The first weeks

Cloudflare is, by any standard, a big company. There's a lot you need to learn, many people you need to get to know first, and a lot of setup steps you need to get through before you're in a position to do actual real productive work.

Joining the company during COVID was challenging. I felt just as excited as I was scared. We were (and still are) fully working from home, I didn't have a Continue reading

Integrating Cloudflare Gateway and Access

We’re excited to announce that you can now set up your Access policies to require that all user traffic to your application is filtered by Cloudflare Gateway. This ensures that all of the traffic to your self-hosted and SaaS applications is secured and centrally logged. You can also use this integration to build rules that determine which users can connect to certain parts of your SaaS applications, even if the application does not support those rules on its own.

Stop threats from returning to your applications and data

We built Cloudflare Access as an internal project to replace our own VPN. Unlike a traditional private network, Access follows a Zero Trust model. Cloudflare’s edge checks every request to protected resources for identity and other signals like device posture (i.e., information about a user’s machine, like Operating system version, if antivirus is running, etc.).

By deploying Cloudflare Access, our security and IT teams could build granular rules for each application and log every request and event. Cloudflare’s network accelerated how users connected. We launched Access as a product for our customers in 2018 to share those improvements with teams of any size.

Over the last two years, we Continue reading

Cloudflare Acquires Linc

Cloudflare has always been about democratizing the Internet. For us, that means bringing the most powerful tools used by the largest of enterprises to the smallest development shops. Sometimes that looks like putting our global network to work defending against large-scale attacks. Other times it looks like giving Internet users simple and reliable privacy services like 1.1.1.1.  Last week, it looked like Cloudflare Pages — a fast, secure and free way to build and host your JAMstack sites.

We see a huge opportunity with Cloudflare Pages. It goes beyond making it as easy as possible to deploy static sites, and extending that same ease of use to building full dynamic applications. By creating a seamless integration between Pages and Cloudflare Workers, we will be able to host the frontend and backend together, at the edge of the Internet and close to your users. The Linc team is joining Cloudflare to help us do just that.

Today, we’re excited to announce the acquisition of Linc, an automation platform to help front-end developers collaborate and build powerful applications. Linc has done amazing work with Frontend Application Bundles (FABs), making dynamic backends more accessible to frontend developers. Their Continue reading

Beat – An Acoustics Inspired DDoS Attack

On the week of Black Friday, Cloudflare automatically detected and mitigated a unique ACK DDoS attack, which we’ve codenamed “Beat”, that targeted a Magic Transit customer. Usually, when attacks make headlines, it’s because of their size. However, in this case, it’s not the size that is unique but the method that appears to have been borrowed from the world of acoustics.

Acoustic inspired attack

As can be seen in the graph below, the attack’s packet rate follows a wave-shaped pattern for over 8 hours. It seems as though the attacker was inspired by an acoustics concept called beat. In acoustics, a beat is a term that is used to describe an interference of two different wave frequencies. It is the superposition of the two waves. When the two waves are nearly 180 degrees out of phase, they create the beating phenomenon. When the two waves merge they amplify the sound and when they are out of sync they cancel one another, creating the beating effect.

Acedemo.org has a nice tool where you can create your own beat wave. As you can see in the screenshot below, the two waves in blue and red are out Continue reading

Configure identity-based policies in Cloudflare Gateway

During Zero Trust Week in October, we released HTTP filtering in Cloudflare Gateway, which expands protection beyond DNS threats to those at the HTTP layer as well. With this feature, Cloudflare WARP proxies all Internet traffic from an enrolled device to a data center in our network. Once there, Cloudflare Gateway enforces organization-wide rules to prevent data loss and protect team members.

However, rules are not one-size-fits-all. Corporate policies can vary between groups or even single users. For example, we heard from customers who want to stop users from uploading files to cloud storage services except for a specific department that works with partners. Beyond filtering, security teams asked for the ability to audit logs on a user-specific basis. If a user account was compromised, they needed to know what happened during that incident.

We’re excited to announce the ability for administrators to create policies based on a user’s identity and correlate that identity to activity in the Gateway HTTP logs. Your team can reuse the same identity provider integration configured in Cloudflare Access and start building policies tailored to your organization today.

Fine-grained rule enforcement

Until today, organizations could protect their users' Internet-bound traffic by configuring DNS and HTTP Continue reading

Computing Euclidean distance on 144 dimensions

Late last year I read a blog post about our CSAM image scanning tool. I remember thinking: this is so cool! Image processing is always hard, and deploying a real image identification system at Cloudflare is no small achievement!

Some time later, I was chatting with Kornel: "We have all the pieces in the image processing pipeline, but we are struggling with the performance of one component." Scaling to Cloudflare needs ain't easy!

The problem was in the speed of the matching algorithm itself. Let me elaborate. As John explained in his blog post, the image matching algorithm creates a fuzzy hash from a processed image. The hash is exactly 144 bytes long. For example, it might look like this:

00e308346a494a188e1043333147267a 653a16b94c33417c12b433095c318012
5612442030d14a4ce82c623f4e224733 1dd84436734e4a5d6e25332e507a8218
6e3b89174e30372d

The hash is designed to be used in a fuzzy matching algorithm that can find "nearby", related images. The specific algorithm is well defined, but making it fast is left to the programmer — and at Cloudflare we need the matching to be done super fast. We want to match thousands of hashes per second, of images passing through our network, against a database of millions of known images. To make this work, Continue reading

A quirk in the SUNBURST DGA algorithm

On Wednesday, December 16, the RedDrip Team from QiAnXin Technology released their discoveries (tweet, github) regarding the random subdomains associated with the SUNBURST malware which was present in the SolarWinds Orion compromise. In studying queries performed by the malware, Cloudflare has uncovered additional details about how the Domain Generation Algorithm (DGA) encodes data and exfiltrates the compromised hostname to the command and control servers.

Background

The RedDrip team discovered that the DNS queries are created by combining the previously reverse-engineered unique guid (based on hashing of hostname and MAC address) with a payload that is a custom base 32 encoding of the hostname. The article they published includes screenshots of decompiled or reimplemented C# functions that are included in the compromised DLL. This background primer summarizes their work so far (which is published in Chinese).

RedDrip discovered that the DGA subdomain portion of the query is split into three parts:

<encoded_guid> + <byte> + <encoded_hostname>

An example malicious domain is:

7cbtailjomqle1pjvr2d32i2voe60ce2.appsync-api.us-east-1.avsvmcloud.com

Where the domain is split into the three parts as

Introducing Cloudflare Pages: the best way to build JAMstack websites

Across multiple cultures around the world, this time of year is a time of celebration and sharing of gifts with the people we care the most about. In that spirit, we thought we'd take this time to give back to the developer community that has been so supportive of Cloudflare for the last 10 years.

Today, we’re excited to announce Cloudflare Pages: a fast, secure and free way to build and host your JAMstack sites.

Today, the path from an idea to a website is paved with good intentions

Websites are the way we express ourselves on the web. It doesn’t matter if you’re a hobbyist with a blog, or the largest of corporations with millions of customers — if you want to reach people outside the confines of 140 280 characters, the web is the place to be.

As a frontend developer, it’s your responsibility to bring this expression to life. And make no mistake — with so many frontend frameworks, tooling, and static site generators at your disposal — it’s a great time to be in your line of work.

That is, of course, right up until the point when you’re ready to show your work off Continue reading

Trend data on the SolarWinds Orion compromise

On Sunday, December 13, FireEye released a report on a sophisticated supply chain attack leveraging SolarWinds' Orion IT monitoring software. The malware was distributed as part of regular updates to Orion and had a valid digital signature.

One of the notable features of the malware is the way it hides its network traffic using a multi-staged approach. First, the malware determines its command and control (C2) server using a domain generation algorithm (DGA) to construct and resolve a subdomain of avsvmcloud[.]com.

These algorithmically generated strings are added as a subdomain of one of the following domain names to create a new fully-qualified domain name to resolve:

.appsync-api[.]eu-west-1[.]avsvmcloud[.]com
.appsync-api[.]us-west-2[.]avsvmcloud[.]com
.appsync-api[.]us-east-1[.]avsvmcloud[.]com
.appsync-api[.]us-east-2[.]avsvmcloud[.]com

An example of such a domain name might look like: hig4gcdkgjkrt24v6isue7ax09nksd[.]appsync-api[.]eu-west-1[.]avsvmcloud[.]com

The DNS query response to a subdomain of one of the above will return a CNAME record that points to another C2 domain, which is used for data exfiltration. The following subdomains were identified as the C2 domains used for data exfiltration:

freescanonline[.]com
deftsecurity[.]com
thedoccloud[.]com
websitetheme[.]com
highdatabase[.]com
incomeupdate[.]com
databasegalore[.]com
panhardware[.]com
zupertech[.]com
virtualdataserver[.]com
Continue reading

Improving Cloudflare’s products and services, one feature request at a time

I started at Cloudflare in April 2018. I was excited to join an innovative company that operates with integrity and takes customer needs into account when planning product roadmaps. After 2.5 years at Cloudflare, this excitement has only grown, as it has become even clearer that our customers’ feedback is essential to our business. At an all-hands meeting this November, Michelle Zatlyn, our co-founder and COO, said that “every time we see things and approach problems from the lens of a customer, we make better decisions.” One of the ways we make these decisions is through Customer Success Managers funneling our customers’ feedback to our product and engineering teams.

As a Strategic Customer Success Manager, I meet regularly with my customers to better understand their experience with Cloudflare and work cross-functionally with our internal teams to continually improve it. One thing my customers often mention to me, regardless of industry or size, is their appreciation that their feedback is not only heard but understood and actioned. We are an engineering-driven company that remains agile enough to Continue reading