Cloudflare has been leaking custom HTTPS sessions

Published on by

Cloudflare has been leaking custom HTTPS sessions image

Cloudflare has reported that under certain circumstances their edge servers were running past the end of a buffer and returning memory that contained private information such as HTTP cookies, authentication tokens, HTTP POST bodies, and other sensitive data. And some of that data had been cached by search engines.

Tavis Ormandy from Google’s Project Zero first spotted the problem and reported this in the Chromium tracker:

It looked like that if an html page hosted behind cloudflare had a specific combination of unbalanced tags, the proxy would intersperse pages of uninitialized memory into the output (kinda like heartbleed, but cloudflare specific and worse for reasons I’ll explain later). My working theory was that this was related to their “ScrapeShield” feature which parses and obfuscates html – but because reverse proxies are shared between customers, it would affect all Cloudflare customers.

We fetched a few live samples, and we observed encryption keys, cookies, passwords, chunks of POST data and even HTTPS requests for other major cloudflare-hosted sites from other users. Once we understood what we were seeing and the implications, we immediately stopped and contacted cloudflare security.

Once Cloudflare was contacted they immediately jumped on the problem and reduced it down to their HTML parser that was used in email obfuscation, Server-side Excludes, and Automatic HTTPS Rewrites.

The issue is now fixed and rolled out to all customers and Cloudflare has a very detailed report on the background, the timeline of the fix, and how they fixed it. They also, worked with Google and other search engines directly to get to remove any cached HTTP responses.

If you’d like to see a list of sites running Cloudflare here is a list of some of the most popular domains.

UPDATE: Laravel News runs on Cloudflare and we received an email this morning saying this site was not affected. Here is a copy of the relevant information from that report:

In our review of these third party caches, we discovered exposed data on approximately 150 of Cloudflare’s customers across our Free, Pro, Business, and Enterprise plans. We have reached out to these customers directly to provide them with a copy of the data that was exposed, help them understand its impact, and help them mitigate that impact.

Your domain is not one of the domains where we have discovered exposed data in any third party caches. The bug has been patched so it is no longer leaking data. However, we continue to work with these caches to review their records and help them purge any exposed data we find. If we discover any data leaked about your domains during this search, we will reach out to you directly and provide you full details of what we have found.

Eric L. Barnes photo

Eric is the creator of Laravel News and has been covering Laravel since 2012.

Filed in:
Cube

Laravel Newsletter

Join 40k+ other developers and never miss out on new tips, tutorials, and more.

Laravel Forge logo

Laravel Forge

Easily create and manage your servers and deploy your Laravel applications in seconds.

Laravel Forge
Tinkerwell logo

Tinkerwell

The must-have code runner for Laravel developers. Tinker with AI, autocompletion and instant feedback on local and production environments.

Tinkerwell
Cut PHP Code Review Time & Bugs into Half with CodeRabbit logo

Cut PHP Code Review Time & Bugs into Half with CodeRabbit

CodeRabbit is an AI-powered code review tool that specializes in PHP and Laravel, running PHPStan and offering automated PR analysis, security checks, and custom review features while remaining free for open-source projects.

Cut PHP Code Review Time & Bugs into Half with CodeRabbit
Join the Mastering Laravel community logo

Join the Mastering Laravel community

Connect with experienced developers in a friendly, noise-free environment. Get insights, share ideas, and find support for your coding challenges. Join us today and elevate your Laravel skills!

Join the Mastering Laravel community
Laravel Idea for PhpStorm logo

Laravel Idea for PhpStorm

Ultimate PhpStorm plugin for Laravel developers, delivering lightning-fast code completion, intelligent navigation, and powerful generation tools to supercharge productivity.

Laravel Idea for PhpStorm
Kirschbaum logo

Kirschbaum

Providing innovation and stability to ensure your web application succeeds.

Kirschbaum
Shift logo

Shift

Running an old Laravel version? Instant, automated Laravel upgrades and code modernization to keep your applications fresh.

Shift
Bacancy logo

Bacancy

Supercharge your project with a seasoned Laravel developer with 4-6 years of experience for just $2500/month. Get 160 hours of dedicated expertise & a risk-free 15-day trial. Schedule a call now!

Bacancy
Lucky Media logo

Lucky Media

Get Lucky Now - the ideal choice for Laravel Development, with over a decade of experience!

Lucky Media
Lunar: Laravel E-Commerce logo

Lunar: Laravel E-Commerce

E-Commerce for Laravel. An open-source package that brings the power of modern headless e-commerce functionality to Laravel.

Lunar: Laravel E-Commerce
Rector logo

Rector

Your partner for seamless Laravel upgrades, cutting costs, and accelerating innovation for successful companies

Rector
LaraJobs logo

LaraJobs

The official Laravel job board

LaraJobs
SaaSykit: Laravel SaaS Starter Kit logo

SaaSykit: Laravel SaaS Starter Kit

SaaSykit is a Multi-tenant Laravel SaaS Starter Kit that comes with all features required to run a modern SaaS. Payments, Beautiful Checkout, Admin Panel, User dashboard, Auth, Ready Components, Stats, Blog, Docs and more.

SaaSykit: Laravel SaaS Starter Kit
MongoDB logo

MongoDB

Enhance your PHP applications with the powerful integration of MongoDB and Laravel, empowering developers to build applications with ease and efficiency. Support transactional, search, analytics and mobile use cases while using the familiar Eloquent APIs. Discover how MongoDB's flexible, modern database can transform your Laravel applications.

MongoDB

The latest

View all →
Handling Request Data Presence in Laravel image

Handling Request Data Presence in Laravel

Read article
First Factor One-Time Passwords for Laravel with OTPZ image

First Factor One-Time Passwords for Laravel with OTPZ

Read article
Managing Request Host Information in Laravel image

Managing Request Host Information in Laravel

Read article
Tim Leland: URL Shorteners, browser extensions, and more image

Tim Leland: URL Shorteners, browser extensions, and more

Read article
HTTP Method Verification in Laravel image

HTTP Method Verification in Laravel

Read article
Packistry is a Self-hosted Composer Repository Made with Laravel image

Packistry is a Self-hosted Composer Repository Made with Laravel

Read article