# Security Detection

> Detect infrastructure and security-critical file changes to trigger security agent review recommendations ensuring proper security oversight for sensitive modifications. Use when you ask "did I touch security-critical files", "should the security agent review this". Detection only. Do NOT use to scan source for injection patterns (use security-scan).

- Skill: `rjmurillo/security-detection` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add rjmurillo/security-detection`
- Raw SKILL.md: https://api.skillmd.com/api/skills/rjmurillo/security-detection/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- License: MIT
- Author: rjmurillo (https://skillmd.com/u/rjmurillo)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/rjmurillo/security-detection

---


# Security Detection Utility

## Triggers

| Trigger Phrase | Operation |
|----------------|-----------|
| `scan for security changes` | detect-infrastructure with staged files |
| `check security-critical files` | detect-infrastructure with file list |
| `run security scan on changes` | detect-infrastructure analysis |
| `do I need a security review` | Risk-level assessment of changed files |
| `check infrastructure changes` | Pattern matching against critical/high lists |

---

## When to Use

Use this skill when:

- Committing changes that may touch infrastructure or security files
- Pre-commit validation for security-sensitive paths
- Determining if a security agent review is needed
- CI pipeline security gate checks

Use the security agent directly instead when:

- You already know security review is needed
- Performing threat modeling or vulnerability assessment
- Reviewing authentication or authorization code in depth

---

## Available Scripts

| Script | Language | Usage |
|--------|----------|-------|
| `detect_infrastructure.py` | Python 3 | Cross-platform |

## Usage

```bash
# Analyze staged files
python detect_infrastructure.py --use-git-staged

# Analyze specific files
python detect_infrastructure.py --files .github/workflows/ci.yml src/auth/login.cs
```

## Output

When security-critical files are detected:

```text
=== Security Review Detection ===

CRITICAL: Security agent review REQUIRED

Matching files:
  [CRITICAL] .github/workflows/deploy.yml
  [HIGH] src/Controllers/AuthController.cs

Run security agent before implementation:
  Task(subagent_type="security", prompt="Review infrastructure changes")
```

When no matches:

```text
No infrastructure/security files detected.
```

## Risk Levels

| Level | Meaning | Action |
|-------|---------|--------|
| CRITICAL | Immediate security implications | Review REQUIRED |
| HIGH | Potential security impact | Review RECOMMENDED |

## Detected Patterns

### Critical (Review Required)

- CI/CD workflows (`.github/workflows/*`)
- Git hook configuration (`{lefthook,.lefthook,lefthook-local,.lefthook-local}.{yml,yaml,json,jsonc,toml}`, `.config/{lefthook,lefthook-local}.{yml,yaml,json,jsonc,toml}`, `.husky/*`)
- Git hook policy (`scripts/validation/git_hook_policy.py`)
- Authentication code (`**/Auth/**`, `**/Security/**`)
- Environment files (`*.env*`)
- Credentials and keys (`*.pem`, `*.key`, `*secret*`)

### High (Review Recommended)

- Build scripts (`build/**/*.ps1`, `scripts/**/*.sh`)
- Container configs (`Dockerfile*`, `docker-compose*`)
- API controllers (`**/Controllers/**`)
- App configuration (`appsettings*.json`)
- Infrastructure as Code (`*.tf`, `*.tfvars`, `*.bicep`)

## Integration

### Pre-commit Hook

Add a named validator job to `lefthook.yml`:

```bash
# Security detection (non-blocking warning)
python3 .claude/skills/security-detection/detect_infrastructure.py --use-git-staged
```

### CI Integration

On a Linux pull-request runner, pass the changed paths explicitly. CI checkouts
do not have a staged diff.

```yaml
- uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
  with:
    fetch-depth: 0

- name: Check security-critical files
  shell: bash
  env:
    BASE_SHA: ${{ github.event.pull_request.base.sha }}
    HEAD_SHA: ${{ github.sha }}
  run: >-
    git diff --no-renames --name-only -z "$BASE_SHA" "$HEAD_SHA"
    | python .claude/skills/security-detection/detect_infrastructure.py
    --files-from-stdin
```

## Exit Codes

| Code | Meaning |
|------|---------|
| 0 | Success (warning shown if matches found, non-blocking) |

The scripts are designed to be non-blocking warnings. They always exit 0 to avoid blocking commits or CI. The warning is informational only.

## Customization

Edit the pattern lists in either script to add or modify detection patterns:

- `CRITICAL_PATTERNS` / `$CriticalPatterns` - Review required
- `HIGH_PATTERNS` / `$HighPatterns` - Review recommended

## Process

1. Gather the list of changed files (staged or explicit)
2. Run pattern matching against critical and high-risk file patterns
3. Report findings with risk level classification
4. Route to security agent if CRITICAL matches found

## Anti-Patterns

| Avoid | Why | Instead |
|-------|-----|---------|
| Skipping detection before commits | Security files slip through unreviewed | Run detection on every commit with infrastructure changes |
| Treating warnings as blocking | Scripts exit 0 intentionally | Use output to inform review decisions, not block commits |
| Hardcoding custom patterns inline | Drifts from canonical pattern lists | Edit CRITICAL_PATTERNS/HIGH_PATTERNS in the scripts |
| Ignoring HIGH-level matches | Potential security impact overlooked | Review HIGH matches, escalate to security agent when uncertain |
| Running only one language script | May miss platform-specific detection | Use whichever script matches your environment |

---

## Verification

After running security detection:

- [ ] Script exited with code 0 (non-blocking)
- [ ] All CRITICAL matches reviewed
- [ ] Security agent routed for CRITICAL findings
- [ ] HIGH matches evaluated for review need
- [ ] Output captured in session log if security-relevant

---

## Related Documents

Backticked paths below are in the `rjmurillo/ai-agents` repository. They do not ship with this skill; a consumer install cannot resolve them.

- `.agents/security/infrastructure-file-patterns.md`. Infrastructure file patterns.
- `.agents/security/static-analysis-checklist.md`. Security agent capabilities.
- `docs/orchestrator-routing-algorithm.md`. Orchestrator routing algorithm.

<!-- vendor-portability: declared. This skill cites .agents/security/infrastructure-file-patterns.md, .agents/security/static-analysis-checklist.md, and docs/orchestrator-routing-algorithm.md as background reading. All three are citations only; the detection patterns documented here are self-contained, so a vendored install loses the further reading, not the capability. Issue #2050. -->