Pattern: Knowledge. The category exists because textual external references have none of the tooling that code dependencies already have — no hash-pin field, no lockfile for prose, and signing the skill package says nothing about what a URL returns at runtime. Mechanism lives in scripts/detector.py: a call-site dataflow scan that follows a fetched response body to the agent's instruction channel or to an executable sink, a gated check for a declared instruction-versus-data convention, and two reads of how wide the declared fetch surface is. Every one of them is an artifact_signal proxy, never…
ast05-untrusted-external-instructions is a community-contributed Claude Code skill in the web-security sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/ast05/ and loads when your prompt matches the skill's trigger.
When to invoke it: Use when a skill's referenced content has no hash pin, when a reviewed skill's external dependency could have changed since review, when triaging a skill-chain injection that no single node's review caught, or when deciding whether a finding belongs here versus AST01 or AST02.
The ast05-untrusted-external-instructions Claude Code skill is built for security engineers, penetration testers, DevSecOps practitioners, and development teams hardening codebases and infrastructure. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 213,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).
mkdir -p ~/.claude/skills/ast05 curl -L https://claudskills.com/skills/ast05/SKILL.md \ -o ~/.claude/skills/ast05/SKILL.md
Or just download SKILL.md directly and drop it into ~/.claude/skills/ast05/. Claude Code auto-discovers it on next session.
Skills live at ~/.claude/skills/ast05/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\ast05\SKILL.md on Windows. See the full install guide for step-by-step instructions.
Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →
The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.
For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.
SKILL.md from the source repository to ~/.claude/skills/ast05/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. ast05-untrusted-external-instructions is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Security category. Learn more at /learn/what-is-a-claude-skill/.If you reference this skill in a blog post, paper, or documentation, you can cite it as:
@misc{ast05-2026,
author = {ClaudSkills},
title = {ast05-untrusted-external-instructions [Claude Code skill]},
year = {2026},
publisher = {ClaudSkills},
url = {https://claudskills.com/skills/ast05/}
}Grade A · scanned 2026-11-01 — free static scan against the OWASP Agentic Skills Top 10.
No risk patterns were found in any of the ten OWASP-aligned categories. How grading works ›
Browse all Security skills in the ClaudSkills registry, or explore these other picks from the same category:
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SKILL.md files, not affiliated with, endorsed by, or sponsored by Anthropic.