Google Online Security Blog: Security

Introducing the Secure Open Source Pilot Program

October 1, 2021

Posted by Meder Kydyraliev and Kim Lewandowski, Google Open Source Security Team

Over the past year we have made a number of investments to strengthen the security of critical open source projects, and recently announced our $10 billion commitment to cybersecurity defense including $100 million to support third-party foundations that manage open source security priorities and help fix vulnerabilities.

Today, we are excited to announce our sponsorship for the Secure Open Source (SOS) pilot program run by the Linux Foundation. This program financially rewards developers for enhancing the security of critical open source projects that we all depend on. We are starting with a $1 million investment and plan to expand the scope of the program based on community feedback.

Why SOS?

SOS rewards a very broad range of improvements that proactively harden critical open source projects and supporting infrastructure against application and supply chain attacks. To complement existing programs that reward vulnerability management, SOS’s scope is comparatively wider in the type of work it rewards, in order to support project developers.

What projects are in scope?

Since there is no one definition of what makes an open source project critical, our selection process will be holistic. During submission evaluation we will consider the guidelines established by the National Institute of Standards and Technology’s definition in response to the recent Executive Order on Cybersecurity along with criteria listed below:

The impact of the project:

How many and what types of users will be affected by the security improvements?
Will the improvements have a significant impact on infrastructure and user security?
If the project were compromised, how serious or wide-reaching would the implications be?

The project’s rankings in existing open source criticality research:

Is the project included in the Havard 2 Census Study of most-used packages, or does it have a score of 0.6 or above in the OpenSSF Critically Score project?

What security improvements qualify?

The program is initially focused on rewarding the following work:

Software supply chain security improvements including hardening CI/CD pipelines and distribution infrastructure. The SLSA framework suggests specific requirements to consider, such as basic provenance generation and verification.
Adoption of software artifact signing and verification. One option to consider is Sigstore's set of utilities (e.g. cosign).
Project improvements that produce higher OpenSSF Scorecard results. For example, a contributor can follow remediation suggestions for the following Scorecard checks:

Code-Review
Branch-Protection
Pinned-Dependencies
Dependency-Update-Tool
Fuzzing

Use of OpenSSF Allstar and remediation of discovered issues.
Earning a CII Best Practice Badge (which also improves the Scorecard results).

We'll continue adding to the above list, so check our FAQ for updates. You may also submit improvements not listed above, if you provide justification and evidence to help us understand the complexity and impact of the work.

Only work completed after October 1, 2021 qualifies for SOS rewards.

Upfront funding is available on a limited case by case basis for impactful improvements of moderate to high complexity over a longer time span. Such requests should explain why funding is required upfront and provide a detailed plan of how the improvements will be landed.

How to participate

Review our FAQ and fill out this form to submit your application.

Please include as much data or supporting evidence as possible to help us evaluate the significance of the project and your improvements.

Reward amounts

Reward amounts are determined based on complexity and impact of work:

$10,000 or more for complicated, high-impact and lasting improvements that almost certainly prevent major vulnerabilities in the affected code or supporting infrastructure.
$5,000-$10,000 for moderately complex improvements that offer compelling security benefits.
$1,000-$5,000 for submissions of modest complexity and impact.
$505 for small improvements that nevertheless have merit from a security standpoint.

Looking Ahead

The SOS program is part of a broader effort to address a growing truth: the world relies on open source software, but widespread support and financial contributions are necessary to keep that software safe and secure. This $1 million investment is just the beginning—we envision the SOS pilot program as the starting point for future efforts that will hopefully bring together other large organizations and turn it into a sustainable, long-term initiative under the OpenSSF. We welcome community feedback and interest from others who want to contribute to the SOS program. Together we can pool our support to give back to the open source community that makes the modern internet possible.

Distroless Builds Are Now SLSA 2

September 22, 2021

Posted by Priya Wadhwa and Appu Goundan, Google Open Source Security Team

A few months ago we announced that we started signing all distroless images with cosign, which allows users to verify that they have the correct image before starting the build process. Signing our images was our first step towards fully securing the distroless supply chain. Since then, we’ve implemented even more accountability in our supply chain and are excited to announce that distroless builds have achieved SLSA 2. SLSA is a security framework for increasing supply chain security, and Level 2 ensures that the build service is tamper resistant.

This means that in addition to a signature, each distroless image now has an associated signed provenance. This provenance is an in-toto attestation and includes information around how each image was built, what command was run, and what build system was used. It also includes any special parameters that were passed in, the exact commit the images were built at, and more. This provenance is a useful tool for builds that need to be audited in the future.

SLSA 2 Requirement	Distroless
Source - Version controlled	Source code in Github
Build - Scripted build	Build script exists as a Tekton Pipeline, invoked as a Google Cloud Build step
Build - Build service	All steps run on Kubernetes with Tekton
Provenance - Available	Provenance is available in the rekor transparency log as an in-toto attestation
Provenance - Authenticated	Provenance is signed with the distroless GCP KMS key
Provenance - Service generated	Provenance is generated by Tekton Chains from a Tekton TaskRun

Achieving SLSA 2 required some changes to the distroless build pipeline: we set up Tekton Pipelines and Tekton Chains in a GKE cluster to automate building images and generating provenance. Every time a pull request is merged to the distroless Github repo, a Tekton Pipeline is triggered. This Pipeline builds the distroless images, and Tekton Chains is responsible for generating signed provenance for each image. Tekton Chains stores the signed provenance alongside the image in an OCI registry and also stores a record of the provenance in the rekor transparency log.

Don't trust us?

You can try the build yourself. Because distroless builds are reproducible, all the information to replicate the build is in the provenance, and you or a trusted third party can build the image yourselves and verify the build is correct by matching image digests.

You can verify an attestation for a distroless image with cosign and the distroless public key:

$ cosign verify-attestation -key cosign.pub gcr.io/distroless/base@sha256:4f8aa0aba190e375a5a53bb71a303c89d9734c817714aeaca9bb23b82135ed91

Verification for gcr.io/distroless/base@sha256:4f8aa0aba190e375a5a53bb71a303c89d9734c817714aeaca9bb23b82135ed91 --

The following checks were performed on each of these signatures:

- The cosign claims were validated

- The signatures were verified against the specified public key

- Any certificates were verified against the Fulcio roots.

...

And you can find the provenance for the image in the rekor transparency log with the rekor-cli tool. For example, you could find the provenance for the above image by using the image’s digest and running:

$ rekor-cli search --sha sha256:4f8aa0aba190e375a5a53bb71a303c89d9734c817714aeaca9bb23b82135ed91

af7a9687d263504ccdb2759169c9903d8760775045c6e7554e365ec2bf29f6f8

$ rekor-cli get --uuid af7a9687d263504ccdb2759169c9903d8760775045c6e7554e365ec2bf29f6f8 --format json | jq -r .Attestation | base64 --decode | jq

{

"_type": "distroless-provenance",

"predicateType": "https://tekton.dev/chains/provenance",

"subject": [

{

"name": "gcr.io/distroless/base",

"digest": {

"sha256": "703a4726aedc9ec7a7e32251087565246db117bb9a141a7993d1c4bb4036660d"

}

{

"name": "gcr.io/distroless/base",

"digest": {

"sha256": "d322ed16d530596c37eee3eb57a039677502aa71f0e4739b0272b1ebd8be9bce"

}

{

"name": "gcr.io/distroless/base",

"digest": {

"sha256": "2dfdd5bf591d0da3f67a25f3fc96d929b256d5be3e0af084db10952e5da2c661"

}

{

"name": "gcr.io/distroless/base",

"digest": {

"sha256": "4f8aa0aba190e375a5a53bb71a303c89d9734c817714aeaca9bb23b82135ed91"

}

{

"name": "gcr.io/distroless/base",

"digest": {

"sha256": "dc0a793d83196a239abf3ba035b3d1a0c7a24184856c2649666e84bc82fc5980"

}

{