CISA has released the "Open Source Software: Security Principles and Practices" guide for federal agencies, but it's a valuable resource for any organization managing open source software (OSS). This guide aligns with Executive Orders 14144 and 14306, establishing a formal process for reviewing and approving OSS. If you're managing OSS in a private organization, this is your blueprint.
The Problem You're Solving
Your teams are already using open source software. The real question is whether you have a structured process to manage the security risks that come with it. Many organizations don't. They often inherit dependencies through package managers, pull in libraries without vetting, and only discover vulnerabilities when scanners flag them.
CISA's guidance treats OSS security as a process problem, not just a tooling issue. You need repeatable workflows for evaluation, approval, patching, and ongoing monitoring. Without these, you're reacting to vulnerabilities instead of managing risk.
What You Need Before Starting
Before implementing a new OSS security process, inventory what you have:
Current state assessment:
- Complete software bill of materials (SBOM) for production systems
- List of approved package repositories (npm, PyPI, Maven Central, etc.)
- Existing vulnerability scanning tools and their coverage
- Current patching SLAs and who owns them
Team resources:
- Someone to own the OSS approval process (security engineer or senior developer)
- Access to legal for license review
- DevOps or platform team to enforce policies in CI/CD
Technical requirements:
- SBOM generation capability (Syft, CycloneDX, or SPDX tools)
- Dependency scanning integrated into your pipeline (Dependabot, Snyk, or similar)
- Version control hooks or CI gates to enforce approval workflow
Don't wait for perfect tooling. Start with spreadsheets and manual reviews, then automate as the process matures.
Step-by-Step Implementation
Phase 1: Establish Your Review Process
Create a lightweight approval workflow that developers can follow. The CISA guide urges agencies to establish a formal review process, but "formal" doesn't mean bureaucratic.
Start with three approval tiers:
Tier 1 - Pre-approved packages: Widely used, actively maintained libraries (React, Express, Django). Document these in a wiki or internal registry. Developers can use them without additional review.
Tier 2 - Standard review: New OSS dependencies that aren't pre-approved. Requires security engineer sign-off based on:
- Project activity (commits in last 90 days)
- Maintainer count (prefer 3+ active maintainers)
- Known vulnerabilities (check CVE databases)
- License compatibility (MIT, Apache 2.0, BSD are typically safe)
Tier 3 - Extended review: OSS with elevated risk (C/C++ libraries, cryptographic code, anything with root/kernel access). Requires architecture review and penetration testing before approval.
Document your criteria in a one-page decision tree. If developers can't figure out which tier applies in 30 seconds, simplify it.
Phase 2: Implement Evaluation Controls
For each new OSS component in Tier 2 or 3, create a review checklist:
Trustworthiness evaluation:
- Repository has a security policy (SECURITY.md)
- Maintainers publish signed releases
- Project uses branch protection and code review
- Recent security audit or bug bounty program exists
Dependency analysis:
- Run
npm audit,pip-audit, or equivalent - Check transitive dependencies (your new library's dependencies)
- Verify no known malicious packages in dependency tree
- Review license cascade (ensure all sub-dependencies are compatible)
Integration risk:
- Identify what data the component accesses
- Document network connections it makes
- Map it to your threat model (does it handle PII, credentials, or payment data?)
Store these evaluations in your ticketing system. When you re-evaluate the same package six months later, you'll want the history.
Phase 3: Build Patching Workflows
The CISA guidance emphasizes patching for good reason. Most OSS breaches exploit known vulnerabilities in outdated dependencies.
Set patching SLAs based on CVSS scores:
- Critical (9.0-10.0): 7 days
- High (7.0-8.9): 30 days
- Medium (4.0-6.9): 90 days
- Low (0.1-3.9): Next quarterly update
Automate what you can:
# Example: Automated weekly dependency updates
# .github/workflows/dependency-updates.yml
name: Dependency Updates
on:
schedule:
- cron: '0 9 * * 1' # Monday 9am
jobs:
update:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v3
- run: npm update
- run: npm audit fix
- uses: peter-evans/create-pull-request@v5
For AI/ML models, which CISA specifically addresses, patching is trickier. You're updating model weights, training data, or inference code. Treat model updates like Tier 3 reviews: test for accuracy regression and adversarial robustness before deploying.
Phase 4: Enforce at the Pipeline
Integrate your approval process into CI/CD:
Pre-commit hooks: Block commits that add unapproved dependencies. Use tools like pre-commit with custom scripts that check against your approved package list.
CI gates: Fail builds if:
- SBOM generation fails
- New dependencies appear without approval ticket reference
- Vulnerability scan finds critical/high CVEs
Deployment gates: Require sign-off from the security team for production deployments that introduce new Tier 2 or Tier 3 packages.
Validation: How to Verify It Works
After 30 days of running your new process, measure:
Coverage metrics:
- Percentage of production dependencies in your SBOM
- Percentage with documented approval in the last 12 months
- Mean time to patch critical vulnerabilities
Process metrics:
- Average approval time for Tier 2 reviews (target: under 2 business days)
- Percentage of builds blocked by unapproved dependencies
- Number of pre-approved packages added (should grow over time)
Run a tabletop exercise: Have a developer propose adding a new package and walk through your process. Time how long it takes. If it's more than 15 minutes of developer time for Tier 2, streamline.
Maintenance and Ongoing Tasks
Quarterly:
- Review your pre-approved package list; remove abandoned projects
- Update patching SLAs based on actual time-to-patch data
- Re-evaluate Tier 3 packages for continued use
When dependencies change:
- Major version bumps trigger new Tier 2 review
- Maintainer changes trigger trustworthiness re-evaluation
- New CVEs in approved packages trigger emergency patching workflow
Annual:
- Audit your process against NIST 800-53 Rev 5 controls SA-12 (supply chain protection)
- Update approval criteria based on lessons learned
- Review OSS license compliance
The CISA guide gives you the framework. Your job is to adapt it to your organization's risk tolerance and development speed. Start small, automate incrementally, and adjust based on what actually slows down your teams versus what catches real risk.
