{"id":"5a310e9b-0426-4dd5-a8aa-f92da3042653","shortId":"S8HarX","kind":"skill","title":"skill-scanner","tagline":"Scan agent skills for security issues before adoption. Detects prompt injection, malicious code, excessive permissions, secret exposure, and supply chain risks.","description":"# Skill Security Scanner\n\nScan agent skills for security issues before adoption. Detects prompt injection, malicious code, excessive permissions, secret exposure, and supply chain risks.\n\n**Important**: Run all scripts from the repository root using the full path via `${CLAUDE_SKILL_ROOT}`.\n\n## When to Use\n- You need to evaluate a skill for prompt injection, malicious code, over-broad permissions, or supply-chain risk before adopting it.\n- You want a static scan plus manual review workflow for a skill directory.\n- The task is to decide whether a skill is safe enough to trust in an agent environment.\n\n## Bundled Script\n\n### `scripts/scan_skill.py`\n\nStatic analysis scanner that detects deterministic patterns. Outputs structured JSON.\n\n```bash\nuv run ${CLAUDE_SKILL_ROOT}/scripts/scan_skill.py <skill-directory>\n```\n\nReturns JSON with findings, URLs, structure info, and severity counts. The script catches patterns mechanically — your job is to evaluate intent and filter false positives.\n\n## Workflow\n\n### Phase 1: Input & Discovery\n\nDetermine the scan target:\n\n- If the user provides a skill directory path, use it directly\n- If the user names a skill, look for it under `plugins/*/skills/<name>/` or `.claude/skills/<name>/`\n- If the user says \"scan all skills\", discover all `*/SKILL.md` files and scan each\n\nValidate the target contains a `SKILL.md` file. List the skill structure:\n\n```bash\nls -la <skill-directory>/\nls <skill-directory>/references/ 2>/dev/null\nls <skill-directory>/scripts/ 2>/dev/null\n```\n\n### Phase 2: Automated Static Scan\n\nRun the bundled scanner:\n\n```bash\nuv run ${CLAUDE_SKILL_ROOT}/scripts/scan_skill.py <skill-directory>\n```\n\nParse the JSON output. The script produces findings with severity levels, URL analysis, and structure information. Use these as leads for deeper analysis.\n\n**Fallback**: If the script fails, proceed with manual analysis using Grep patterns from the reference files.\n\n### Phase 3: Frontmatter Validation\n\nRead the SKILL.md and check:\n\n- **Required fields**: `name` and `description` must be present\n- **Name consistency**: `name` field should match the directory name\n- **Tool assessment**: Review `allowed-tools` — is Bash justified? Are tools unrestricted (`*`)?\n- **Model override**: Is a specific model forced? Why?\n- **Description quality**: Does the description accurately represent what the skill does?\n\n### Phase 4: Prompt Injection Analysis\n\nLoad `${CLAUDE_SKILL_ROOT}/references/prompt-injection-patterns.md` for context.\n\nReview scanner findings in the \"Prompt Injection\" category. For each finding:\n\n1. Read the surrounding context in the file\n2. Determine if the pattern is **performing** injection (malicious) or **discussing/detecting** injection (legitimate)\n3. Skills about security, testing, or education commonly reference injection patterns — this is expected\n\n**Critical distinction**: A security review skill that lists injection patterns in its references is documenting threats, not attacking. Only flag patterns that would execute against the agent running the skill.\n\n### Phase 5: Behavioral Analysis\n\nThis phase is agent-only — no pattern matching. Read the full SKILL.md instructions and evaluate:\n\n**Description vs. instructions alignment**:\n- Does the description match what the instructions actually tell the agent to do?\n- A skill described as \"code formatter\" that instructs the agent to read ~/.ssh is misaligned\n\n**Config/memory poisoning**:\n- Instructions to modify `CLAUDE.md`, `MEMORY.md`, `settings.json`, `.mcp.json`, or hook configurations\n- Instructions to add itself to allowlists or auto-approve permissions\n- Writing to `~/.claude/` or any agent configuration directory\n\n**Scope creep**:\n- Instructions that exceed the skill's stated purpose\n- Unnecessary data gathering (reading files unrelated to the skill's function)\n- Instructions to install other skills, plugins, or dependencies not mentioned in the description\n\n**Information gathering**:\n- Reading environment variables beyond what's needed\n- Listing directory contents outside the skill's scope\n- Accessing git history, credentials, or user data unnecessarily\n\n### Phase 6: Script Analysis\n\nIf the skill has a `scripts/` directory:\n\n1. Load `${CLAUDE_SKILL_ROOT}/references/dangerous-code-patterns.md` for context\n2. Read each script file fully (do not skip any)\n3. Check scanner findings in the \"Malicious Code\" category\n4. For each finding, evaluate:\n   - **Data exfiltration**: Does the script send data to external URLs? What data?\n   - **Reverse shells**: Socket connections with redirected I/O\n   - **Credential theft**: Reading SSH keys, .env files, tokens from environment\n   - **Dangerous execution**: eval/exec with dynamic input, shell=True with interpolation\n   - **Config modification**: Writing to agent settings, shell configs, git hooks\n5. Check PEP 723 `dependencies` — are they legitimate, well-known packages?\n6. Verify the script's behavior matches the SKILL.md description of what it does\n\n**Legitimate patterns**: `gh` CLI calls, `git` commands, reading project files, JSON output to stdout are normal for skill scripts.\n\n### Phase 7: Supply Chain Assessment\n\nReview URLs from the scanner output and any additional URLs found in scripts:\n\n- **Trusted domains**: GitHub, PyPI, official docs — normal\n- **Untrusted domains**: Unknown domains, personal sites, URL shorteners — flag for review\n- **Remote instruction loading**: Any URL that fetches content to be executed or interpreted as instructions is high risk\n- **Dependency downloads**: Scripts that download and execute binaries or code at runtime\n- **Unverifiable sources**: References to packages or tools not on standard registries\n\n### Phase 8: Permission Analysis\n\nLoad `${CLAUDE_SKILL_ROOT}/references/permission-analysis.md` for the tool risk matrix.\n\nEvaluate:\n\n- **Least privilege**: Are all granted tools actually used in the skill instructions?\n- **Tool justification**: Does the skill body reference operations that require each tool?\n- **Risk level**: Rate the overall permission profile using the tier system from the reference\n\nExample assessments:\n- `Read Grep Glob` — Low risk, read-only analysis skill\n- `Read Grep Glob Bash` — Medium risk, needs Bash justification (e.g., running bundled scripts)\n- `Read Grep Glob Bash Write Edit WebFetch Task` — High risk, near-full access\n\n## Confidence Levels\n\n| Level | Criteria | Action |\n|-------|----------|--------|\n| **HIGH** | Pattern confirmed + malicious intent evident | Report with severity |\n| **MEDIUM** | Suspicious pattern, intent unclear | Note as \"Needs verification\" |\n| **LOW** | Theoretical, best practice only | Do not report |\n\n**False positive awareness is critical.** The biggest risk is flagging legitimate security skills as malicious because they reference attack patterns. Always evaluate intent before reporting.\n\n## Output Format\n\n```markdown\n## Skill Security Scan: [Skill Name]\n\n### Summary\n- **Findings**: X (Y Critical, Z High, ...)\n- **Risk Level**: Critical / High / Medium / Low / Clean\n- **Skill Structure**: SKILL.md only / +references / +scripts / full\n\n### Findings\n\n#### [SKILL-SEC-001] [Finding Type] (Severity)\n- **Location**: `SKILL.md:42` or `scripts/tool.py:15`\n- **Confidence**: High\n- **Category**: Prompt Injection / Malicious Code / Excessive Permissions / Secret Exposure / Supply Chain / Validation\n- **Issue**: [What was found]\n- **Evidence**: [code snippet]\n- **Risk**: [What could happen]\n- **Remediation**: [How to fix]\n\n### Needs Verification\n[Medium-confidence items needing human review]\n\n### Assessment\n[Safe to install / Install with caution / Do not install]\n[Brief justification for the assessment]\n```\n\n**Risk level determination**:\n- **Critical**: Any high-confidence critical finding (prompt injection, credential theft, data exfiltration)\n- **High**: High-confidence high-severity findings or multiple medium findings\n- **Medium**: Medium-confidence findings or minor permission concerns\n- **Low**: Only best-practice suggestions\n- **Clean**: No findings after thorough analysis\n\n## Reference Files\n\n| File | Purpose |\n|------|---------|\n| `references/prompt-injection-patterns.md` | Injection patterns, jailbreaks, obfuscation techniques, false positive guide |\n| `references/dangerous-code-patterns.md` | Script security patterns: exfiltration, shells, credential theft, eval/exec |\n| `references/permission-analysis.md` | Tool risk tiers, least privilege methodology, common skill permission profiles |\n\n## Limitations\n- Use this skill only when the task clearly matches the scope described above.\n- Do not treat the output as a substitute for environment-specific validation, testing, or expert review.\n- Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.","tags":["skill","scanner","antigravity","awesome","skills","sickn33","agent-skills","agentic-skills","ai-agent-skills","ai-agents","ai-coding","ai-workflows"],"capabilities":["skill","source-sickn33","skill-skill-scanner","topic-agent-skills","topic-agentic-skills","topic-ai-agent-skills","topic-ai-agents","topic-ai-coding","topic-ai-workflows","topic-antigravity","topic-antigravity-skills","topic-claude-code","topic-claude-code-skills","topic-codex-cli","topic-codex-skills"],"categories":["antigravity-awesome-skills"],"synonyms":[],"warnings":[],"endpointUrl":"https://skills.sh/sickn33/antigravity-awesome-skills/skill-scanner","protocol":"skill","transport":"skills-sh","auth":{"type":"none","details":{"cli":"npx skills add sickn33/antigravity-awesome-skills","source_repo":"https://github.com/sickn33/antigravity-awesome-skills","install_from":"skills.sh"}},"qualityScore":"0.700","qualityRationale":"deterministic score 0.70 from registry signals: · indexed on github topic:agent-skills · 34515 github stars · SKILL.md body (8,794 chars)","verified":false,"liveness":"unknown","lastLivenessCheck":null,"agentReviews":{"count":0,"score_avg":null,"cost_usd_avg":null,"success_rate":null,"latency_p50_ms":null,"narrative_summary":null,"summary_updated_at":null},"enrichmentModel":"deterministic:skill-github:v1","enrichmentVersion":1,"enrichedAt":"2026-04-22T12:51:47.237Z","embedding":null,"createdAt":"2026-04-18T21:45:02.798Z","updatedAt":"2026-04-22T12:51:47.237Z","lastSeenAt":"2026-04-22T12:51:47.237Z","tsv":"'/.claude':513 '/.ssh':485 '/dev/null':231,235 '/references':229 '/references/dangerous-code-patterns.md':594 '/references/permission-analysis.md':800 '/references/prompt-injection-patterns.md':357 '/scripts':233 '/scripts/scan_skill.py':140,251 '/skill.md':209 '/skills':197 '001':973 '1':168,371,589 '15':981 '2':230,234,237,379,597 '3':292,392,607 '4':349,616 '5':437,670 '6':579,682 '7':716 '723':673 '8':793 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Includes installer CLI, bundles, workflows, and official/community skill collections.","skill_md_sha":"cabad391e2606e9becdbb49936be88ea64ec6bd6","skill_md_path":"skills/skill-scanner/SKILL.md","default_branch":"main","skill_tree_url":"https://github.com/sickn33/antigravity-awesome-skills/tree/main/skills/skill-scanner"},"layout":"multi","source":"github","category":"antigravity-awesome-skills","frontmatter":{"name":"skill-scanner","description":"Scan agent skills for security issues before adoption. Detects prompt injection, malicious code, excessive permissions, secret exposure, and supply chain risks."},"skills_sh_url":"https://skills.sh/sickn33/antigravity-awesome-skills/skill-scanner"},"updatedAt":"2026-04-22T12:51:47.237Z"}}