Category Archives: Online Security Blog

The latest news and insights from Google on security and safety on the Internet

The Android Platform Security Model

Posted by Jeff Vander Stoep, Android Security & Privacy Team

Each Android release comes with great new security and privacy features. When it comes to implementing these new features we always look at ways to measure the impact with data that demonstrates the effectiveness of these improvements. But how do these features map to an overall strategy?
Last week, we released a whitepaper describing The Android Platform Security Model. Specifically we discuss:
  • The security model which has implicitly informed the Android platform’s security design from the beginning, but has not been formally published or described outside of Google.
  • The context in which this security model must operate, including the scale of the Android ecosystem and its many form factors and use cases.
  • The complex threat model Android must address.
  • How Android’s reference implementation in the Android Open Source Project (AOSP) enacts the security model.
  • How Android’s security systems have evolved over time to address the threat model.
Android is fundamentally based on a multi-party consent1 model: an action should only happen if the involved parties consent to it. Most importantly, apps are not considered to be fully authorized agents for the user. There are some intentional deviations from the security model and we discuss why these exist and the value that they provide to users. Finally, openness is a fundamental value in Android: from how we develop and publish in open source, to the open access users and developers have in finding or publishing apps, and the open communication mechanisms we provide for inter-app interactions which facilitate innovation within the app ecosystem.
We hope this paper provides useful information and background to all the academic and security researchers dedicated to further strengthening the security of the Android ecosystem. Happy reading!
Acknowledgements: This post leveraged contributions from René Mayrhofer, Chad Brubaker, and Nick Kralevich

Notes

  1. The term ‘consent’ here and in the paper is used to refer to various technical methods of declaring or enforcing a party’s intent, rather than the legal requirement or standard found in many privacy legal regimes around the world. ↩

Gmail making email more secure with MTA-STS standard

Posted by Nicolas Lidzborski, Senior Staff Software Engineer, Google Cloud and Nicolas Kardas, Senior Product Manager, Google Cloud 

We’re excited to announce that Gmail will become the first major email provider to follow the new SMTP MTA Strict Transport Security (MTA-STS) RFC 8461 and SMTP TLS Reporting RFC 8460 internet standards. Those new email security standards are the result of three years of collaboration within IETF, with contributions from Google and other large email providers.

SMTP alone is vulnerable to man-in-the-middle attacks

Like all mail providers, Gmail uses Simple Mail Transfer Protocol (SMTP) to send and receive mail messages. SMTP alone only provides best-effort security with opportunistic encryption, and many SMTP servers do not prevent certain types of malicious attacks intercepting email traffic in transit.

SMTP is therefore vulnerable to man-in-the-middle attacks. Man-in-the-middle is an attack where communication between two servers is intercepted and possibly changed without detection. Real attacks and prevention were highlighted in our research published in November 2015. MTA-STS will help prevent these types of attacks.

MTA-STS uses encryption and authentication to reduce vulnerabilities

A MTA-STS policy for your domain means that you request external mail servers sending messages to your domain to verify the SMTP connection is authenticated with a valid public certificate and encrypted with TLS 1.2 or higher. This can be combined with TLS reporting, that means your domain can request daily reports from external mail servers with information about the success or failure of emails sent to your domain according to MTA-STS policy.

Gmail is starting MTA-STS adherence. We hope others will follow

Gmail the first major provider to follow the new standard, initially launching in Beta on April 10th 2019. This means Gmail will honor MTA-STS and TLS reporting policies configured when sending emails to domains that have defined these policies. We hope many other email providers will soon adopt these new standards that make email communications more secure.

Email domain administrators should set up DNS records and web server endpoint to configure MTA-STS and TLS reporting policies for incoming emails. Use our Help Center to find out how to set up an MTA-STS policy with your DNS server. G Suite admins can use the G Suite Updates blog to see what MTA-STS means for G Suite domains.

Android Security & Privacy Year in Review 2018: Keeping two billion users, and their data, safe and sound

Posted by Meghan Kelly, Android Security & Privacy Team
We're excited to release today the 2018 Android Security and Privacy Year in Review. This year's report highlights the advancements we made in Android throughout the year, and how we've worked to keep the overall ecosystem secure.
Our goal is to be open and transparent in everything we do. We want to make sure we keep our users, partners, enterprise customers, and developers up to date on the latest security and privacy enhancements in as close to real-time as possible. To that end, in 2018 we prioritized regularly providing updates through our blogs and our new Transparency Reports, which give a quarterly ecosystem overview. In this year-in-review, you'll see fewer words and more links to relevant articles from the previous year. Check out our Android Security Center to get the latest on these advancements.
In this year's report, some of our top highlights include:
  • New features in Google Play Protect
  • Ecosystem and Potentially Harmful Application family highlights
  • Updates on our vulnerability rewards program
  • Platform security enhancements
We're also excited to have Dave Kleidermacher, Vice President of Android Security and Privacy, give you a rundown of the highlights from this report. Watch his video below to learn more.

Managed Google Play earns key certifications for security and privacy


Posted by Mike Burr, Android Enterprise Platform Specialist

[Cross-posted from the Android Enterprise Keyword Blog]



With managed Google Play, organizations can build a customized and secure mobile application storefront for their teams, featuring public and private applications. Organizations' employees can take advantage of the familiarity of a mobile app store to browse and download company-approved apps.
As with any enterprise-grade platform, it's critical that the managed Google Play Store operates with the highest standards of privacy and security. Managed Google Play has been awarded three important industry designations that are marks of meeting the strict requirements for information security management practices.
Granted by the International Organization for Standardization, achieving ISO 27001 certification demonstrates that a company meets stringent privacy and security standards when operating an Information Security Management System (ISMS). Additionally, managed Google Play received SOC 2 and 3 reports, which are benchmarks of strict data management and privacy controls. These designations and auditing procedures are developed by the American Institute of Certified Public Accountants (AICPA).
Meeting a high bar of security management standards
To earn the ISO 27001 certification, auditors from Ernst and Young performed a thorough audit of managed Google Play based on established privacy principles. The entire methodology of documentation and procedures for managing other companies' data are reviewed during an audit, and must be made available for regular compliance review. Companies that use managed Google Play are assured their data is managed in compliance with this industry standard. Additionally, ISO 27001 certification is in line with GDPR compliance.
Secure data management
With SOC 2 and SOC 3 reports, the focus is on controls relevant to data security, availability, processing integrity, confidentiality and privacy, which are verified through auditing reports. In managed Google Play, the data and private applications that enter Google's systems are administered according to strict protocols, including determinations for who can view them and under what conditions. Enterprises require and receive the assurance that their information is handled with the utmost confidentiality and that the integrity of their data is preserved. For many companies, the presence of an SOC 2 and 3 report is a requirement when selecting a specific service. These reports prove that a service company has met and is abiding by best practices set forth by AICPA to ensure data security.
Our ongoing commitment to enterprise security
With managed Google Play, companies' private apps for internal use are protected with a set of verified information security management processes and policies to ensure intellectual property is secure. This framework includes managed Google Play accounts that are used by enterprise mobility management (EMM) partners to manage devices.
Our commitment is that Android will continue to be a leader in enterprise security. As your team works across devices and shares mission-critical data through applications hosted in managed Google Play, you have the assurance of a commitment to providing your enterprise the highest standards of security and privacy.

Open-sourcing Sandboxed API

Posted by Christian Blichmann & Robert Swiecki, ISE Sandboxing team

Many software projects process data which is externally generated, and thus potentially untrusted. For example, this could be the conversion of user-provided picture files into different formats, or even executing user-generated software code.
When a software library parsing such data is sufficiently complex, it might fall victim to certain types of security vulnerabilities: memory corruption bugs or certain other types of problems related to the parsing logic (e.g. path traversal issues). Those vulnerabilities can have serious security implications.

In order to mitigate those problems, developers frequently employ software isolation methods, a process commonly referred to as sandboxing. By using sandboxing methods, developers make sure that only resources (files, networking connections and other operating system resources) which are deemed necessary are accessible to the code involved in parsing user-generated content. In the worst-case scenario, when potential attackers gain remote code execution rights within the scope of a software project, a sandboxing technique can contain them, protecting the rest of the software infrastructure.

Sandboxing techniques must be highly resistant to attacks and sufficiently protect the rest of the operating system, yet must be sufficiently easy-to-use for software developers. Many popular software containment tools might not sufficiently isolate the rest of the OS, and those which do, might require time-consuming redefinition of security boundaries for each and every project that should be sandboxed.

Sandbox once, use anywhere

To help with this task, we are open-sourcing our battle-tested project called Sandboxed API. Sandboxed API makes it possible to create security policies for individual software libraries. This concept allows to create reusable and secure implementations of functionality residing within popular software libraries, yet is granular enough to protect the rest of used software infrastructure.

As Sandboxed API serves the purpose of accessing individual software functions inside a sandboxed library, we are also making publicly available our core sandboxing project, Sandbox2. This is now part of Sandboxed API and provides the underlying sandboxing primitives. It can be also used standalone to isolate arbitrary Linux processes, but is considered a lower-level API.

Overview

Sandboxed API is currently implemented for software libraries written in the C programming language (or providing C bindings), though we might add support for more programming runtimes in the future.

From a high-level perspective, Sandboxed API separates the library to be sandboxed and its callers into two separate OS processes: the host binary and the sandboxee. Actual library calls are then marshalled by an API object on the host side and send via interprocess communication to the sandboxee where an RPC stub unmarshals and forwards calls to the original library.

Both the API object (SAPI object) and the RPC stub are provided by the project, with the former being auto-generated by an interface generator. Users just need to provide a sandbox policy, a set of system calls that the underlying library is allowed to make, as well as the resources it is allowed to access and use. Once ready, a library based on sandboxed API can easily be reused in other projects.

The resulting API of the SAPI object is similar to the one of the original library. For example, when using zlib, the popular compression library, a code snippet like this compresses a chunk of data (error handling omitted for brevity):


void Compress(const std::string& chunk, std::string* out) {
 z_stream zst{};
 constexpr char kZlibVersion[] = "1.2.11";
 CHECK(deflateInit_(&zst, /*level=*/4, kZlibVersion, sizeof(zst)) == Z_OK);

 zst.avail_in = chunk.size();
 zst.next_in = reinterpret_cast<uint8_t*>(&chunk[0]);
 zst.avail_out = out->size();
 zst.next_out = reinterpret_cast<uint8_t*>(&(*out)[0]);
 CHECK(deflate(&zst, Z_FINISH) != Z_STREAM_ERROR);
 out->resize(zst.avail_out);

 deflateEnd(&zst);
}


Using Sandboxed API, this becomes:
void CompressSapi(const std::string& chunk, std::string* out) {
 sapi::Sandbox sandbox(sapi::zlib::zlib_sapi_embed_create());
 CHECK(sandbox.Init().ok());
 sapi::zlib::ZlibApi api(&sandbox);

 sapi::v::Array<uint8_t> s_chunk(&chunk[0], chunk.size());
 sapi::v::Array<uint8_t> s_out(&(*out)[0], out->size());
 CHECK(sandbox.Allocate(&s_chunk).ok() && sandbox.Allocate(&s_out).ok());
 sapi::v::Struct<sapi::zlib::z_stream> s_zst;
 
 constexpr char kZlibVersion[] = "1.2.11";
 sapi::v::Array<char> s_version(kZlibVersion, ABSL_ARRAYSIZE(kZlibVersion));
 CHECK(api.deflateInit_(s_zst.PtrBoth(), /*level=*/4, s_version.PtrBefore(),
                         sizeof(sapi::zlib::z_stream).ValueOrDie() == Z_OK));

 CHECK(sandbox.TransferToSandboxee(&s_chunk).ok());
 s_zst.mutable_data()->avail_in = chunk.size();
 s_zst.mutable_data()->next_in = reinterpet_cast<uint8_t*>(s_chunk.GetRemote());
 s_zst.mutable_data()->avail_out = out->size();
 s_zst.mutable_data()->next_out = reinterpret_cast<uint8_t*>(s_out.GetRemote());
 CHECK(api.deflate(s_zst.PtrBoth(), Z_FINISH).ValueOrDie() != Z_STREAM_ERROR);
 CHECK(sandbox.TransferFromSandboxee(&s_out).ok());
 out->resize(s_zst.data().avail_out);

 CHECK(api.deflateEnd(s_zst.PtrBoth()).ok());
}
As you can see, when using Sandboxed API there is extra code for setting up the sandbox itself and for transferring memory to and from the sandboxee, but other than that, the code flow stays the same.

Try for yourself

It only takes a few moments to get up and running with Sandboxed API. If Bazel is installed:
sudo apt-get install python-typing python-clang-7 libclang-7-dev linux-libc-dev
git clone github.com/google/sandboxed-api && cd sandboxed-api
bazel test //sandboxed_api/examples/stringop:main_stringop
This will download the necessary dependencies and run the project through its paces. More detailed instructions can be found in our Getting Started guide and be sure to check out the examples for Sandboxed API.

Where do we go from here?

Sandboxed API and Sandbox2 are used by many teams at Google. While the project is mature, we do have plans for the future beyond just maintaining it:

  • Support more operating systems - So far, only Linux is supported. We will look into bringing Sandboxed API to the Unix-like systems like the BSDs (FreeBSD, OpenBSD) and macOS. A Windows port is a bigger undertaking and will require some more groundwork to be done.
  • New sandboxing technologies - With things like hardware-virtualization becoming almost ubiquitous, confining code into VMs for sandboxing opens up new possibilities.
  • Build system - Right now, we are using Bazel to build everything, including dependencies. We acknowledge that this is not how everyone will want to use it, so CMake support is high on our priority list.
  • Spread the word - Use Sandboxed API to secure open source projects. If you want to get involved, this work is also eligible for the Patch Reward Program.
Get involved

We are constantly looking at improving Sandboxed API and Sandbox2 as well as adding more features: supporting more programming runtimes, different operating systems or alternative containment technologies.

Check out the Sandboxed API GitHub repository. We will be happy to consider your contributions and look forward to any suggestions to help improve and extend this code.

Disclosing vulnerabilities to protect users across platforms

Posted by Clement Lecigne, Threat Analysis Group

On Wednesday, February 27th, we reported two 0-day vulnerabilities — previously publicly-unknown vulnerabilities — one affecting Google Chrome and another in Microsoft Windows that were being exploited together.

To remediate the Chrome vulnerability (CVE-2019-5786), Google released an update for all Chrome platforms on March 1; this update was pushed through Chrome auto-update. We encourage users to verify that Chrome auto-update has already updated Chrome to 72.0.3626.121 or later.

The second vulnerability was in Microsoft Windows. It is a local privilege escalation in the Windows win32k.sys kernel driver that can be used as a security sandbox escape. The vulnerability is a NULL pointer dereference in win32k!MNGetpItemFromIndex when NtUserMNDragOver() system call is called under specific circumstances.

We strongly believe this vulnerability may only be exploitable on Windows 7 due to recent exploit mitigations added in newer versions of Windows. To date, we have only observed active exploitation against Windows 7 32-bit systems.

Pursuant to Google’s vulnerability disclosure policy, when we discovered the vulnerability we reported it to Microsoft. Today, also in compliance with our policy, we are publicly disclosing its existence, because it is a serious vulnerability in Windows that we know was being actively exploited in targeted attacks. The unpatched Windows vulnerability can still be used to elevate privileges or combined with another browser vulnerability to evade security sandboxes. Microsoft have told us they are working on a fix.

As mitigation advice for this vulnerability users should consider upgrading to Windows 10 if they are still running an older version of Windows, and to apply Windows patches from Microsoft when they become available. We will update this post when they are available.

Android Security Improvement update: Helping developers harden their apps, one thwarted vulnerability at a time

Posted by Patrick Mutchler and Meghan Kelly, Android Security & Privacy Team


[Cross-posted from the Android Developers Blog]

Helping Android app developers build secure apps, free of known vulnerabilities, means helping the overall ecosystem thrive. This is why we launched the Application Security Improvement Program five years ago, and why we're still so invested in its success today.

What the Android Security Improvement Program does

When an app is submitted to the Google Play store, we scan it to determine if a variety of vulnerabilities are present. If we find something concerning, we flag it to the developer and then help them to remedy the situation.

Think of it like a routine physical. If there are no problems, the app runs through our normal tests and continues on the process to being published in the Play Store. If there is a problem, however, we provide a diagnosis and next steps to get back to healthy form.

Over its lifetime, the program has helped more than 300,000 developers to fix more than 1,000,000 apps on Google Play. In 2018 alone, the program helped over 30,000 developers fix over 75,000 apps. The downstream effect means that those 75,000 vulnerable apps are not distributed to users with the same security issues present, which we consider a win.

What vulnerabilities are covered

The App Security Improvement program covers a broad range of security issues in Android apps. These can be as specific as security issues in certain versions of popular libraries (ex: CVE-2015-5256) and as broad as unsafe TLS/SSL certificate validation.

We are continuously improving this program's capabilities by improving the existing checks and launching checks for more classes of security vulnerability. In 2018, we deployed warnings for six additional security vulnerability classes including:

  1. SQL Injection
  2. File-based Cross-Site Scripting
  3. Cross-App Scripting
  4. Leaked Third-Party Credentials
  5. Scheme Hijacking
  6. JavaScript Interface Injection

Ensuring that we're continuing to evolve the program as new exploits emerge is a top priority for us. We are continuing to work on this throughout 2019.

Keeping Android users safe is important to Google. We know that app security is often tricky and that developers can make mistakes. We hope to see this program grow in the years to come, helping developers worldwide build apps users can truly trust.

Google Play Protect in 2018: New updates to keep Android users secure


Posted by Rahul Mishra and Tom Watkins, Android Security & Privacy Team
[Cross-posted from the Android Developers Blog]

In 2018, Google Play Protect made Android devices running Google Play some of the most secure smartphones available, scanning over 50 billion apps everyday for harmful behaviour.
Android devices can genuinely improve people's lives through our accessibility features, Google Assistant, digital wellbeing, Family Link, and more — but we can only do this if they are safe and secure enough to earn users' long term trust. This is Google Play Protect's charter and we're encouraged by this past year's advancements.

Google Play Protect, a refresher

Google Play Protect is the technology we use to ensure that any device shipping with the Google Play Store is secured against potentially harmful applications (PHA). It is made up of a giant backend scanning engine to aid our analysts in sourcing and vetting applications made available on the Play Store, and built-in protection that scans apps on users' devices, immobilizing PHA and warning users.
This technology protects over 2 billion devices in the Android ecosystem every day.

What's new

On by default
We strongly believe that security should be a built-in feature of every device, not something a user needs to find and enable. When security features function at their best, most users do not need to be aware of them. To this end, we are pleased to announce that Google Play Protect is now enabled by default to secure all new devices, right out of the box. The user is notified that Google Play Protect is running, and has the option to turn it off whenever desired.

New and rare apps
Android is deployed in many diverse ways across many different users. We know that the ecosystem would not be as powerful and vibrant as it is today without an equally diverse array of apps to choose from. But installing new apps, especially from unknown sources, can carry risk.
Last year we launched a new feature that notifies users when they are installing new or rare apps that are rarely installed in the ecosystem. In these scenarios, the feature shows a warning, giving users pause to consider whether they want to trust this app, and advising them to take additional care and check the source of installation. Once Google has fully analyzed the app and determined that it is not harmful, the notification will no longer display. In 2018, this warning showed around 100,000 times per day
Context is everything: warning users on launch
It's easy to misunderstand alerts when presented out of context. We're trained to click through notifications without reading them and get back to what we were doing as quickly as possible. We know that providing timely and context-sensitive alerts to users is critical for them to be of value. We recently enabled a security feature first introduced in Android Oreo which warns users when they are about to launch a potentially harmful app on their device.

This new warning dialog provides in-context information about which app the user is about to launch, why we think it may be harmful and what might happen if they open the app. We also provide clear guidance on what to do next. These in-context dialogs ensure users are protected even if they accidentally missed an alert.
Auto-disabling apps
Google Play Protect has long been able to disable the most harmful categories of apps on users devices automatically, providing robust protection where we believe harm will be done.
In 2018, we extended this coverage to apps installed from Play that were later found to have violated Google Play's policies, e.g. on privacy, deceptive behavior or content. These apps have been suspended and removed from the Google Play Store.
This does not remove the app from user device, but it does notify the user and prevents them from opening the app accidentally. The notification gives the option to remove the app entirely.
Keeping the Android ecosystem secure is no easy task, but we firmly believe that Google Play Protect is an important security layer that's used to protect users devices and their data while maintaining the freedom, diversity and openness that makes Android, well, Android.
Acknowledgements: This post leveraged contributions from Meghan Kelly and William Luh.

How we fought bad apps and malicious developers in 2018


Posted by Andrew Ahn, Product Manager, Google Play
[Cross-posted from the Android Developers Blog]

Google Play is committed to providing a secure and safe platform for billions of Android users on their journey discovering and experiencing the apps they love and enjoy. To deliver against this commitment, we worked last year to improve our abuse detection technologies and systems, and significantly increased our team of product managers, engineers, policy experts, and operations leaders to fight against bad actors.
In 2018, we introduced a series of new policies to protect users from new abuse trends, detected and removed malicious developers faster, and stopped more malicious apps from entering the Google Play Store than ever before. The number of rejected app submissions increased by more than 55 percent, and we increased app suspensions by more than 66 percent. These increases can be attributed to our continued efforts to tighten policies to reduce the number of harmful apps on the Play Store, as well as our investments in automated protections and human review processes that play critical roles in identifying and enforcing on bad apps.
In addition to identifying and stopping bad apps from entering the Play Store, our Google Play Protect system now scans over 50 billion apps on users' devices each day to make sure apps installed on the device aren't behaving in harmful ways. With such protection, apps from Google Play are eight times less likely to harm a user's device than Android apps from other sources.
Here are some areas we've been focusing on in the last year and that will continue to be a priority for us in 2019:

Protecting User Privacy

Protecting users' data and privacy is a critical factor in building user trust. We've long required developers to limit their device permission requests to what's necessary to provide the features of an app. Also, to help users understand how their data is being used, we've required developers to provide prominent disclosures about the collection and use of sensitive user data. Last year, we rejected or removed tens of thousands of apps that weren't in compliance with Play's policies related to user data and privacy.
In October 2018, we announced a new policy restricting the use of the SMS and Call Log permissions to a limited number of cases, such as where an app has been selected as the user's default app for making calls or sending text messages. We've recently started to remove apps from Google Play that violate this policy. We plan to introduce additional policies for device permissions and user data throughout 2019.

Developer integrity

We find that over 80% of severe policy violations are conducted by repeat offenders and abusive developer networks. When malicious developers are banned, they often create new accounts or buy developer accounts on the black market in order to come back to Google Play. We've further enhanced our clustering and account matching technologies, and by combining these technologies with the expertise of our human reviewers, we've made it more difficult for spammy developer networks to gain installs by blocking their apps from being published in the first place.

Harmful app contents and behaviors

As mentioned in last year's blog post, we fought against hundreds of thousands of impersonators, apps with inappropriate content, and Potentially Harmful Applications (PHAs). In a continued fight against these types of apps, not only do we apply advanced machine learning models to spot suspicious apps, we also conduct static and dynamic analyses, intelligently use user engagement and feedback data, and leverage skilled human reviews, which have helped in finding more bad apps with higher accuracy and efficiency.
Despite our enhanced and added layers of defense against bad apps, we know bad actors will continue to try to evade our systems by changing their tactics and cloaking bad behaviors. We will continue to enhance our capabilities to counter such adversarial behavior, and work relentlessly to provide our users with a secure and safe app store.
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Open sourcing ClusterFuzz

Posted by Abhishek Arya, Oliver Chang, Max Moroz, Martin Barbella and Jonathan Metzman (ClusterFuzz team)

[Cross-posted from the Google Open-Source Blog]

Fuzzing is an automated method for detecting bugs in software that works by feeding unexpected inputs to a target program. It is effective at finding memory corruption bugs, which often have serious security implications. Manually finding these issues is both difficult and time consuming, and bugs often slip through despite rigorous code review practices. For software projects written in an unsafe language such as C or C++, fuzzing is a crucial part of ensuring their security and stability.

In order for fuzzing to be truly effective, it must be continuous, done at scale, and integrated into the development process of a software project. To provide these features for Chrome, we wrote ClusterFuzz, a fuzzing infrastructure running on over 25,000 cores. Two years ago, we began offering ClusterFuzz as a free service to open source projects through OSS-Fuzz.

Today, we’re announcing that ClusterFuzz is now open source and available for anyone to use.
We developed ClusterFuzz over eight years to fit seamlessly into developer workflows, and to make it dead simple to find bugs and get them fixed. ClusterFuzz provides end-to-end automation, from bug detection, to triage (accurate deduplication, bisection), to bug reporting, and finally to automatic closure of bug reports.

ClusterFuzz has found more than 16,000 bugs in Chrome and more than 11,000 bugs in over 160 open source projects integrated with OSS-Fuzz. It is an integral part of the development process of Chrome and many other open source projects. ClusterFuzz is often able to detect bugs hours after they are introduced and verify the fix within a day.

Check out our GitHub repository. You can try ClusterFuzz locally by following these instructions. In production, ClusterFuzz depends on some key Google Cloud Platform services, but you can use your own compute cluster. We welcome your contributions and look forward to any suggestions to help improve and extend this infrastructure. Through open sourcing ClusterFuzz, we hope to encourage all software developers to integrate fuzzing into their workflows.