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CD Heimdall - Security Scanner for AI Agent Skills

Scan OpenClaw skills for malicious patterns before installation. Context-aware scanning with AI-powered narrative analysis.

modbender/skill-library-mcp Agent Skills author: modbender MIT 5 files body ≈ 1 272 tokens Open the sourcegithub.com↗ analyzed 2 d ago

Scan OpenClaw skills for malicious patterns before installation.

As a process D 39/100 · Unfinished process — weak spots: result and completion, when it triggers, inputs and preconditions

AnalyzerGitHubAI and agentsWriting and documentstype and topics are labelled automatically from the skill text
Runs in: OpenClaw Claude / Claude Code ChatGPT / Codex Gemini CLI Cursor GitHub Copilot / VS Code Qwen Code Kimi Code CLI Z.ai (GLM) DeepSeek (Deep Code) Mistral Vibe LangChain (deepagents) Goose OpenCode
JSON
Technical rating
C
70/100
safety, quality, tests
Safety 60%
62
Quality 40%
82
Run on models
none yet
Process rating
D
39/100
Unfinished process
Result and completion w 14
0
Inputs and preconditions w 11
0
Failures and branches w 10
0
the three weakest of ten parameters · all ten

What is at stake

Medium-severity findings: the skill is probably honest, but read what alarmed the scanner.

Dangerous commands medium severity

Below is the worst case for this category. The finding here is medium: the guard saw a sign, not a proof.

If you install

The skill contains commands that delete files, rewrite disks or execute code fetched from the network. The agent may run them without asking if it believes the instructions require it.

For the author

Replace destructive commands with safe equivalents that ask for confirmation, scope them to one folder, and stop piping curl into a shell: pin a version and a checksum.

How to improve

    For the model run — optional
    • Your own cases (evals/evals.json, 4–6 real requests with expected answers): the full check would then run those instead of a model-drafted suite.
    • A spec.yaml with trigger phrases and assertions — a behaviour contract for CI; `skilltest init` writes a template.

    Guard findings · 18

    ✓ No critical or high findings

    Medium and low: 18
    • medium Dangerous commands cmd-pipe-to-shell README.md:64
      Downloads and executes remote code from an unrecognised host (pipe to shell) (documentation of a security skill)
      | ⚡ Auto-Approve | LLMSecurity | always allow, curl \| bash patterns |
      security skill
    • low Risky intent intent-wallet-secrets scripts/skill-scan.py:285
      Handles crypto-wallet secrets (seed / mnemonic / private key) — a classic stealer target (detector / deny-list definition)
      (r"(seed|mnemonic)\s*(phrase|words?)", Severity.CRITICAL, "crypto_wallet", "Seed phrase reference"),
      detector
    • low Risky intent intent-wallet-secrets skill-scan.py:285
      Handles crypto-wallet secrets (seed / mnemonic / private key) — a classic stealer target (detector / deny-list definition)
      (r"(seed|mnemonic)\s*(phrase|words?)", Severity.CRITICAL, "crypto_wallet", "Seed phrase reference"),
      detector
    • low Dangerous commands cmd-privilege SKILL.md:74
      Privilege escalation / world-writable permissions (documentation of a security skill)
      - **privilege**: sudo -S, chmod 777
      security skill
    • low Dangerous commands cmd-shell-rc SKILL.md:157
      Writes to a shell startup file (documentation of a security skill)
      echo 'alias skill-scan="~/clawd/skills/heimdall/scripts/skill-scan.py"' >> ~/.bashrc
      security skill

    A further 13 matches are quotations in this security skill's documentation and are not counted as findings.

    Files scanned: 5. Evidence is masked. Grey chips explain why severity was lowered.

    Against the Agent Skills spec

    • warning name-format name should be kebab-case (lowercase letters, digits, hyphens)

    Process rating: all ten parameters 39/100

    • 0Result and completion. Does not say what the result is
    • 0Inputs and preconditions. Does not say what the process needs to start
    • 0Failures and branches. Linear process with no failure handling
    • 0Progress reporting. Says nothing while it works
    • 20When it triggers. No condition that starts the skill
    • 30Running it twice. 1 mutating operations with no state check
    • 40Consistency. Frontmatter name (Heimdall - Security Scanner for AI Agent Skills) differs from the folder (heimdall)
    • 60Tools and files. Uses tools (bash, web) that frontmatter does not declare
    • 100Steps. 25 steps
    • 100Execution cost. Instruction body is 1272 tokens
    • medium Safety rules and hard prohibitions inside a skill: they belong in the system prompt, here they protect nothing

    Everything here is measured from the skill text rather than judged by a model, so the numbers are checkable. A parameter weighs more when it is a more common reason for the process to stall.

    Quality signals

    • +5Description has no quoted example phrases that should trigger the skill
    • +4Description does not say when NOT to use the skill (false activations)
    • +3Output format is not stated: the model decides each time
    • +1No license
    • +2Single-language instructions
    • +3Description length 123: enough signal without eating the budget
    • +4Structure: 19 headings
    • +3Step-by-step instructions: 25 items
    • +4Has examples (8 code blocks)
    • +3All 1 scripts are documented

    Quality base 70; lint remarks subtract, signals add up to 100. Result: 82.