Use when Codex is already in the validation phase of a security scan or the user explicitly asks to determine whether one or more candidate security findings are valid. Do not use as the primary trigger for full PR, commit, branch, patch, or repository scans.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Security Validation
## Objective
Take candidate findings from discovery and produce the strongest evidence-backed validation assessment you can. Prefer targeted, non-interactive reproduction or falsification when it is feasible and proportionate, but use focused code tracing when dynamic execution is blocked by missing services, unavailable infrastructure, or excessive setup relative to the candidate and scan scope.
## Artifact Resolution
The path references in this skill are the default locations for this phase.
If the user explicitly provides a different path for a required input or output, use the user-provided path instead of the corresponding default path referenced in this skill.
If a required input is still missing, stop and ask the user for it before continuing.
Use the shared scan artifact path conventions in `../../references/scan-artifacts.md`.
## Workflow
1. Before starting, create a detailed validation rubric with up to five criteria for the candidate.
2. For each candidate finding, identify the claimed attacker input, vulnerable sink, and preconditions.
3. Choose the validation path using the strongest realistic method available:
…
The line at the top of this page pins the label git:20260606.a4decec, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
A 17 of 17 checks passed. Fixed automatic checks with no AI involved, so the same checks give the same answer every run.
pass: Frontmatter block present
pass: Frontmatter declares a name
pass: Frontmatter declares a description
pass: Size between 200 bytes and 200 KB (10562 bytes)
pass: No zero-width or bidi control characters
pass: No instruction hidden inside an HTML comment
pass: No link to an exfiltration or paste host
pass: No credential-shaped string
pass: No instruction to send local credentials anywhere
pass: No text hidden with inline styles
pass: No prompt-injection phrasing
pass: No curl or wget piped into a shell
pass: No recursive delete of root, home or parent
pass: No instruction to read or print local credentials
pass: No base64 blob over 200 characters
pass: No link to a raw IP address
pass: No script tag
Source
GitHub
cowork-os/cowork-os · 535 stars · license MIT · pushed 2026-11-06 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_ymr2gsxfmdxd7tey
GET https://markdownregistry.com/api/v1/resolve?ref=cowork-os/cowork-os/validation
GET https://markdownregistry.com/api/v1/blob/1defe029fdec20610dcbb9d898963f903ea3ebf10a287628c9ddc9ca7789f335
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
cowork-os/cowork-os · resources/plugin-packs/codex-security/skills/attack-path-analysis/SKILL.md · Use when Codex is already in the attack-path-analysis phase of a security scan or the user explicitly asks to trace a…
cowork-os/cowork-os · resources/plugin-packs/codex-security/skills/deep-security-scan/SKILL.md · Use when the user asks for a deep, exhaustive, multi-pass, or variance-reducing repository-wide Codex Security scan…
cowork-os/cowork-os · resources/plugin-packs/codex-security/skills/finding-discovery/SKILL.md · Use when Codex is already in the finding-discovery phase of a security scan or the user explicitly asks to discover…
cowork-os/cowork-os · resources/plugin-packs/codex-security/skills/fix-finding/SKILL.md · Use when the user explicitly asks to fix and verify a validated or plausible security finding. Do not use as the…
cowork-os/cowork-os · resources/plugin-packs/codex-security/skills/security-diff-scan/SKILL.md · Use when the user asks for a security review of a pull request, commit, branch diff, working-tree patch, or other…
cowork-os/cowork-os · resources/plugin-packs/codex-security/skills/security-scan/SKILL.md · Use when the user asks for a repository-wide or scoped-path security scan.
cowork-os/cowork-os · resources/plugin-packs/codex-security/skills/threat-model/SKILL.md · Use when Codex is already in the threat-modeling phase of a security scan, the user explicitly invokes $threat-model…
cowork-os/cowork-os · resources/skills/1password/SKILL.md · Set up and use 1Password CLI (op). Use when installing the CLI, enabling desktop app integration, signing in (single or…
