Securing Your Supply Chain by Building with FRSCA

### Overview In this talk, Mike Lieberman (Co-founder and CTO at Kusari, SLSA steering committee member, and CNCF TAG Security lead) introduces FRSCA (Factory for Repeatable Secure Creation of Artifacts). FRSCA is an OpenSSF project housed under the Supply Chain Integrity Working Group that provides a reference implementation of the CNCF Secure Software Factory architecture. The project aims to secure build pipelines against software supply chain attacks—such as build-time tampering, compromised source ingestion, and untrusted artifact publication—by orchestrating a hardened, opinionated toolchain in Kubernetes and providing a pipeline framework that abstracts governance and security away from developers.

### Key Topics - **Supply Chain Threat Landscape**: Addressing vulnerabilities highlighted by incidents like SolarWinds, including unapproved pipeline alterations, compromised build environments signing with legitimate keys, and untrusted dependency pulling. - **Secure Software Factory Principles**: Employing zero-trust isolation, ephemeral build environments, non-falsifiable provenance, and defense-in-depth. - **Shared Responsibility in CI/CD**: Distinguishing between build service responsibilities (ephemeral environments, isolation, tamper-evident seals) and developer responsibilities (scripting builds, supplying build configurations). - **Pipeline Framework with CUE**: Utilizing the CUE configuration language to generate Kubernetes and Tekton resources, enforcing organizational policies, schema constraints, and required steps (e.g., mandatory SBOMs or security scans) without placing configuration burdens on developers.

### Technical Details - **Core Architecture & Tooling**: - **Build Orchestration**: Tekton and Tekton Chains handle triggers, pipeline runs, and task runs, generating cryptographic attestations. - **Workload & Node Attestation**: SPIFFE/SPIRE runs in a separate trust domain to enforce workload and node identity, preventing runtime container swaps or unauthorized cluster nodes from obtaining signed builds. - **Secrets & Signing**: HashiCorp Vault with the Transit plugin issues cryptographic signatures and manages scoped secret access mapped directly to SPIFFE identities. - **Policy Enforcement**: Admission controllers such as Kyverno (with plans to support Open Policy Agent / OPA) ensure only policy-compliant pipelines and images execute. - **Runtime Observability**: Tetragon (via eBPF) observes container runtime execution to detect malicious actions such as unexpected external network calls (e.g., reaching out to suspicious domains). - **CUE-Based Pipeline Abstraction**: Because CUE is non-Turing complete and natively imports Kubernetes Go APIs, FRSCA uses it to validate configurations, constrain allowed build types (e.g., restricting pipelines to Go and Buildpacks while rejecting Python), enforce naming schemes, and automatically generate Tekton tasks, pipelines, Kyverno policies, and ConfigMaps. - **Demonstration & Verification**: Lieberman demonstrates triggering a build via a Gitea pull request, generating an artifact verified using `crane` and `cosign`, inspecting base64-decoded SLSA provenance generated by Tekton Chains, and generating SBOMs (such as via Syft).

### Takeaways FRSCA provides an opinionated blueprint across OpenSSF, CNCF, and Continuous Delivery Foundation (CDF) technologies, showing how modern cloud-native systems can meet high SLSA requirements out of the box. Future work for FRSCA includes building a dedicated CLI, deeper integration with TUF and in-toto, speeding up complex CUE pipelines, and refining the abstraction framework into a turnkey secure-by-design build platform.