ci-cd-security

SKILL.md

CI/CD Security Scanner

This skill turns the model into a workflow-YAML scanner. Read the file, walk the detection rules, report findings with severity and a concrete rewrite. No tools to install, no commands to run — the analysis is the model reading the YAML.

The rules encode the current consensus from Astral, OpenSSF, GitHub Security Lab, Chainguard, and the zizmor audit set. The goal is to flag the same patterns those tools would flag, without needing to run them.

Mental model

Every workflow sits on a 2x2: privileged vs unprivileged crossed with trusted vs untrusted code. Compromise happens at exactly one cell: privileged workflow running untrusted code. The rules below are ways to detect when a workflow ends up in that cell.

Privileged = has secrets, write permissions, or produces a sensitive artifact (release, deploy, comment, label).

Untrusted code = anything a fork PR author can influence: PR source code, PR title, PR body, commit messages, branch names, files the workflow reads, caches, artifacts produced by another untrusted workflow.

When unsure whether a value is trusted, treat it as untrusted. The cost of a false positive is a code review comment; the cost of a false negative is a supply chain compromise.

Scan procedure

For each workflow file the user provides, walk these passes in order. Each pass corresponds to a class of attack.