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ClusterFuzzLite: Continuous fuzzing for all

11 Listopad, 2021 - 19:13
Posted by Jonathan Metzman, Google Open Source Security Team

In recent years, continuous fuzzing has become an essential part of the software development lifecycle. By feeding unexpected or random data into a program, fuzzing catches bugs that would otherwise slip through the most thorough manual checks and provides coverage that would take staggering human effort to replicate. NIST’s guidelines for software verification, recently released in response to the White House Executive Order on Improving the Nation’s Cybersecurity, specify fuzzing among the minimum standard requirements for code verification.

Today, we are excited to announce ClusterFuzzLite, a continuous fuzzing solution that runs as part of CI/CD workflows to find vulnerabilities faster than ever before. With just a few lines of code, GitHub users can integrate ClusterFuzzLite into their workflow and fuzz pull requests to catch bugs before they are committed, enhancing the overall security of the software supply chain.

Since its release in 2016, over 500 critical open source projects have integrated into Google’s OSS-Fuzz program, resulting in over 6,500 vulnerabilities and 21,000 functional bugs being fixed. ClusterFuzzLite goes hand-in-hand with OSS-Fuzz, by catching regression bugs much earlier in the development process.

Large projects including systemd and curl are already using ClusterFuzzLite during code review, with positive results. According to Daniel Stenberg, author of curl, “When the human reviewers nod and have approved the code and your static code analyzers and linters can't detect any more issues, fuzzing is what takes you to the next level of code maturity and robustness. OSS-Fuzz and ClusterFuzzLite help us maintain curl as a quality project, around the clock, every day and every commit.”

With the release of ClusterFuzzLite, any project can integrate this essential testing standard and benefit from fuzzing. ClusterFuzzLite offers many of the same features as ClusterFuzz, such as continuous fuzzing, sanitizer support, corpus management, and coverage report generation. Most importantly, it’s easy to set up and works with closed source projects, making ClusterFuzzLite a convenient option for any developer who wants to fuzz their software.


With ClusterFuzzLite, fuzzing is no longer just an idealized "bonus" round of testing for those who have access to it, but a critical must-have step that everyone can use continuously on every software project. By finding and preventing bugs before they enter the codebase we can build a more secure software ecosystem.

To learn more, check out the ClusterFuzzLite documentation. ClusterFuzzLite currently supports GitHub ActionsGoogle Cloud Build and Prow. We built this with CI system extensibility in mind, and adding support for other CI systems is straightforward. Please contact us if you’re interested in contributing support, or have any questions, feedback or feature requests.
Kategorie: Hacking & Security

Trick & Treat! ???? Paying Leets and Sweets for Linux Kernel privescs and k8s escapes

1 Listopad, 2021 - 17:41
Posted by Eduardo Vela, Google Bug Hunters Team 

Starting today and for the next 3 months (until January 31 2022), we will pay 31,337 USD to security researchers that exploit privilege escalation in our lab environment with a patched vulnerability, and 50,337 USD to those that use a previously unpatched vulnerability, or a new exploit technique.

We are constantly investing in the security of the Linux Kernel because much of the internet, and Google—from the devices in our pockets, to the services running on Kubernetes in the cloud—depend on the security of it. We research its vulnerabilities and attacks, as well as study and develop its defenses.

But we know that there is more work to do. That’s why we have decided to build on top of our kCTF VRP from last year and triple our previous reward amounts (for at least the next 3 months).

Our base rewards for each publicly patched vulnerability is 31,337 USD (at most one exploit per vulnerability), but the reward can go up to 50,337 USD in two cases:
  • If the vulnerability was otherwise unpatched in the Kernel (0day)
  • If the exploit uses a new attack or technique, as determined by Google
We hope the new rewards will encourage the security community to explore new Kernel exploitation techniques to achieve privilege escalation and drive quicker fixes for these vulnerabilities. It is important to note, that the easiest exploitation primitives are not available in our lab environment due to the hardening done on Container-Optimized OS. Note this program complements Android's VRP rewards, so exploits that work on Android could also be eligible for up to 250,000 USD (that's in addition to this program).

The mechanics are:
  1. Connect to the kCTF VRP cluster, obtain root and read the flag (read this writeup for how it was done before, and this threat model for inspiration), and then submit your flag and a checksum of your exploit in this form.
  2. (If applicable) report vulnerabilities to upstream.
    • We strongly recommend including a patch since that could qualify for an additional reward from our Patch Reward Program, but please report vulnerabilities upstream promptly once you confirm they are exploitable.
  3. Report your finding to Google VRP once all patches are publicly available (we don't want to receive details of unpatched vulnerabilities ahead of the public.)
    • Provide the exploit code and the algorithm used to calculate the hash checksum.
    • A rough description of the exploit strategy is welcome.
Reports will be triaged on a weekly basis. If anyone has problems with the lab environment (if it's unavailable, technical issues or other questions), contact us on Discord in #kctf. You can read more details about the program here. Happy hunting!
Kategorie: Hacking & Security