Netskope named a Leader in the 2024 Gartner® Magic Quadrant™ for Security Service Edge. Get the report

  • Why Netskope chevron

    Changing the way networking and security work together.

  • Our Customers chevron

    Netskope serves more than 3,000 customers worldwide including more than 25 of the Fortune 100

  • Our Partners chevron

    We partner with security leaders to help you secure your journey to the cloud.

Still Highest in Execution.
Still Furthest in Vision.

Learn why 2024 Gartner® Magic Quadrant™ named Netskope a Leader for Security Service Edge the third consecutive year.

Get the report
Netskope Named a Leader in the 2024 Gartner® Magic Quadrant™ for Security Service Edge graphic for menu
We help our customers to be Ready for Anything

See our customers
Woman smiling with glasses looking out window
Netskope’s partner-centric go-to-market strategy enables our partners to maximize their growth and profitability while transforming enterprise security.

Learn about Netskope Partners
Group of diverse young professionals smiling
Your Network of Tomorrow

Plan your path toward a faster, more secure, and more resilient network designed for the applications and users that you support.

Get the white paper
Your Network of Tomorrow
Introducing the Netskope One Platform

Netskope One is a cloud-native platform that offers converged security and networking services to enable your SASE and zero trust transformation.

Learn about Netskope One
Abstract with blue lighting
Embrace a Secure Access Service Edge (SASE) architecture

Netskope NewEdge is the world’s largest, highest-performing security private cloud and provides customers with unparalleled service coverage, performance and resilience.

Learn about NewEdge
Netskope Cloud Exchange

The Netskope Cloud Exchange (CE) provides customers with powerful integration tools to leverage investments across their security posture.

Learn about Cloud Exchange
Netskope video
The platform of the future is Netskope

Intelligent Security Service Edge (SSE), Cloud Access Security Broker (CASB), Cloud Firewall, Next Generation Secure Web Gateway (SWG), and Private Access for ZTNA built natively into a single solution to help every business on its journey to Secure Access Service Edge (SASE) architecture.

Go to Products Overview
Netskope video
Next Gen SASE Branch is hybrid — connected, secured, and automated

Netskope Next Gen SASE Branch converges Context-Aware SASE Fabric, Zero-Trust Hybrid Security, and SkopeAI-powered Cloud Orchestrator into a unified cloud offering, ushering in a fully modernized branch experience for the borderless enterprise.

Learn about Next Gen SASE Branch
People at the open space office
Designing a SASE Architecture For Dummies

Get your complimentary copy of the only guide to SASE design you’ll ever need.

Get the eBook
Make the move to market-leading cloud security services with minimal latency and high reliability.

Learn about NewEdge
Lighted highway through mountainside switchbacks
Safely enable the use of generative AI applications with application access control, real-time user coaching, and best-in-class data protection.

Learn how we secure generative AI use
Safely Enable ChatGPT and Generative AI
Zero trust solutions for SSE and SASE deployments

Learn about Zero Trust
Boat driving through open sea
Netskope achieves FedRAMP High Authorization

Choose Netskope GovCloud to accelerate your agency’s transformation.

Learn about Netskope GovCloud
Netskope GovCloud
  • Resources chevron

    Learn more about how Netskope can help you secure your journey to the cloud.

  • Blog chevron

    Learn how Netskope enables security and networking transformation through security service edge (SSE)

  • Events and Workshops chevron

    Stay ahead of the latest security trends and connect with your peers.

  • Security Defined chevron

    Everything you need to know in our cybersecurity encyclopedia.

Security Visionaries Podcast

The Intersection of Zero Trust and National Security
On the latest episode of Security Visionaries, co-hosts Max Havey and Emily Wearmouth sit down for a conversation with guest Chase Cunningham (AKA Dr. Zero Trust) about zero trust and national security.

Play the podcast
The Intersection of Zero Trust and National Security
Latest Blogs

Read how Netskope can enable the Zero Trust and SASE journey through security service edge (SSE) capabilities.

Read the blog
Sunrise and cloudy sky
SASE Week 2023: Your SASE journey starts now!

Replay sessions from the fourth annual SASE Week.

Explore sessions
SASE Week 2023
What is SASE?

Learn about the future convergence of networking and security tools in today’s cloud dominant business model.

Learn about SASE
  • Company chevron

    We help you stay ahead of cloud, data, and network security challenges.

  • Leadership chevron

    Our leadership team is fiercely committed to doing everything it takes to make our customers successful.

  • Customer Solutions chevron

    We are here for you and with you every step of the way, ensuring your success with Netskope.

  • Training and Certification chevron

    Netskope training will help you become a cloud security expert.

Supporting sustainability through data security

Netskope is proud to participate in Vision 2045: an initiative aimed to raise awareness on private industry’s role in sustainability.

Find out more
Supporting Sustainability Through Data Security
Thinkers, builders, dreamers, innovators. Together, we deliver cutting-edge cloud security solutions to help our customers protect their data and people.

Meet our team
Group of hikers scaling a snowy mountain
Netskope’s talented and experienced Professional Services team provides a prescriptive approach to your successful implementation.

Learn about Professional Services
Netskope Professional Services
Secure your digital transformation journey and make the most of your cloud, web, and private applications with Netskope training.

Learn about Training and Certifications
Group of young professionals working

Evasive Phishing Campaign Steals Cloud Credentials Using Cloudflare R2 and Turnstile

Aug 14 2023

From February to July 2023, Netskope Threat Labs has been tracking a staggering 61-fold increase in traffic to phishing pages hosted in Cloudflare R2. The majority of the phishing campaigns target Microsoft login credentials, although there are some pages targeting Adobe, Dropbox, and other cloud apps. The attacks have been targeting victims mainly in North America and Asia, across different segments, led by the technology, financial services, and banking sectors.

These phishing campaigns abuse the free hosting service Cloudflare R2 to distribute static phishing pages. To evade detection, they are using two noteworthy techniques to prevent scanners and URL analyzers from detecting the phishing pages. First, they are using Cloudflare Turnstile to protect the pages with a CAPTCHA. This technique prevents scanners and analyzers from visiting the URLs and observing their contents while allowing victims easy access to the pages. Second, many of the pages only load the malicious content if it was passed by another malicious referring site. This helps ensure that only the intended targets are served the phishing content.  

Let’s take a closer look at how these campaigns function.

Cloudflare R2 hosting phishing pages

Cloudflare R2 is a fairly new cloud storage service which opened for beta in May 2022 and was made publicly available in August 2022, offering static hosting at little-to-no cost. Similar to Amazon S3, Google GCS, or Azure Blob Storage, objects hosted on Cloudflare R2 can optionally be granted public access. Users can either connect the storage to their own domain, or Cloudflare R2 will provide a unique subdomain for each bucket. Cloud services that offer free or low-cost object storage are commonly abused by attackers to host malicious content. R2 is one of the latest apps to join a long list of cloud apps being abused.  In July, R2 was one of 167 different cloud apps being abused to deliver malicious content.  

Over the past six months, Netskope Threat Labs has observed a staggering increase of traffic to phishing pages hosted on Cloudflare R2. The phishing pages are primarily targeting Microsoft credentials.

The attackers take advantage of the free subdomain provided by Cloudflare, which makes the URLs relatively easy to identify. Users should look for URLs with the following pattern:


Cloudflare R2 hosting a Microsoft phishing page

Using Cloudflare Turnstile for evasion 

Cloudflare Turnstile is a free service, designed to protect websites from bots and other malicious traffic, and a smart CAPTCHA alternative that can be embedded into any website without sending traffic through Cloudflare. It has the option to hide the CAPTCHA to visitors, but can also show a traditional verification page as well. 

Some of the phishing campaigns we observed abusing Cloudflare R2 are also abusing Turnstile to both convince their target that the phishing site is legitimate and to hide the actual phishing page from security scanners. Submitting the phishing pages to online scanners like doesn’t reach the actual phishing site, as it  fails the CAPTCHA test.

Cloudflare Turnstile customized to look like it’s Microsoft’s Captcha

Attackers used explicit rendering of Cloudflare Turnstile so they could modify the CAPTCHA page to appear as if it were actually requested by the service users were about to log on to. This can easily be done by modifying the site-name to any legitimate service, which is “Microsoft Security” in this case pictured above. 

Using redirects and URL parameters for evasion

Apart from abusing Cloudflare Turnstile, some phishing pages perform additional detection evasion by hiding the phishing page until certain conditions are met. The malicious website requires a referring site to include a timestamp after a hash symbol in the URL to display the actual phishing page. On the other hand, the referring site requires a phishing site passed on to it as a parameter. So, if no URL parameter is passed to the referring site, the visitor will be redirected to This is a clever technique as accessing both the referring site and the effective page by itself will hide the actual phishing page, making it look benign. This both helps prevent URL scanners and bots from visiting the page and helps ensure that only the intended victims can see the phishing content.

Deobfuscated script showing referring site requiring a URL

The malicious site also requires a timestamp passed on the URL from the referrer for it to display the actual phishing page. If a user accessed the malicious site directly, they would be shown a custom error message.

Accessing the phishing page directly.

The only way to access the actual phishing page is by passing the malicious URL as an argument to the referring site. For these phishing campaigns observed, both the referrer and the malicious site are hosted on Cloudflare R2.

Successfully accessing the malicious page

Using Fingerprint BotD for evasion

The phishing site also uses the free and open-source bot detection library Fingerprint BotD to identify phishing pages crawled by bot. It sends a custom error message (ERROR CODE 102 or 99) when it detects a bot accessing the page.

Phishing page using Fingerprint BotD


R2 was one of 162 cloud apps being abused to host malicious content in July 2022. The phishing pages hosted there use multiple techniques to evade analysis, including using Cloudflare Turnstile for CAPTCHAs, Fingerprint BotD for bot detection, and URL parameter checks. All URLs associated with this campaign have been reported to Cloudflare.  To block these types of phishing attempts, Netskope uses ML-based inline, out-of-band phishing detection engines, and threat intelligence systems. Users can also spot similar phishing pages hosted on R2 by inspecting the URL for the pattern pub-*


The scams and phishing pages described in the post are easily recognisable by the domain pattern pub-* Users can avoid becoming victims of the types of attacks described in this post by checking the URL. Users should always access important pages, such as their banking portal or webmail, by typing the URL directly into the web browser instead of using search engines or clicking any other links.

Netskope Threat Labs recommends that organizations review their security policies to ensure that they are adequately protected against these and similar phishing pages and scams:

  • Inspect all HTTP and HTTPS traffic, including all web and cloud traffic, to prevent users from visiting malicious websites. Netskope customers can configure their Netskope NG-SWG with a URL filtering policy to block known phishing and scam sites, and a threat protection policy to inspect all web content to identify unknown phishing and scam sites using a combination of signatures, threat intelligence, and machine learning.
  • Use  Remote Browser Isolation (RBI) technology to provide additional protection when there is a need to visit websites that fall in categories that can present higher risk, like Newly Observed and Newly Registered Domains.


Below are the IOCs related to the web pages analyzed in this blog post.





















































hxxp://pub-0e459479bb894ae6a3446ba7783965b0.r2[.]dev/docusign encrypted.htm






hxxp://pub-b2955bd5cc5a447cba7f9017e8915538.r2[.]dev/[email protected]








author image
Jan Michael Alcantara
Jan Michael Alcantara is an experienced incident responder with a background on forensics, threat hunting, and incident analysis.

Stay informed!

Subscribe for the latest from the Netskope Blog