Claude Code Security — Hardening & Best Practices

---
name: safe-agent
model: claude-sonnet
permission-mode: default
disallowedTools: [Bash]  # Kein Shell
---

---
name: developer-agent
permission-mode: default
tools: [Read, Write, Edit, Bash, Git]
disallowedTools: []
---

---
name: devops-agent
permission-mode: elevated
---

---
name: enterprise-agent
permission-mode: enterprise
audit-log: true
require-approval: true
approval-threshold: ["write", "bash"]
---

---
name: debug-agent
permission-mode: bypass  # Nur für lokales Debugging!
---

---
name: sandboxed-agent
sandbox:
  filesystem: /tmp/workspace
  allowed-dirs:
    - /data/input
    - /data/output
  blocked-dirs:
    - /etc
    - /root
    - /sys
  readonly: [/data/input]  # Only read
  readwrite: [/data/output]  # Read+Write
---

---
name: network-restricted
sandbox:
  network:
    enabled: true
    allowed-domains:
      - api.example.com
      - data.example.com
    blocked-domains:
      - facebook.com
      - malicious-site.com
    protocols:
      - https  # Only HTTPS
    rate_limit:
      requests_per_minute: 60
      data_per_hour: 1GB
---

---
name: resource-limited
sandbox:
  process:
    cpu_limit: 50%
    memory_limit: 1GB
    timeout: 300s
    max_file_descriptors: 256
    no_spawn: true  # Cannot spawn child processes
---

# .claude/hooks/pre-tool-use/security-validator.js
module.exports = {
  name: 'security-validator',
  event: 'pre-tool-use',
  async handler(context) {
    const { tool, args, agent_id } = context;

    // Rule 1: Block SQL Injection patterns
    if (tool === 'Write' || tool === 'Bash') {
      const dangerous = [
        /DROP\s+TABLE/i,
        /DELETE\s+FROM/i,
        /TRUNCATE/i,
        /exec\(/,
        /eval\(/,
        /rm\s+-rf/
      ];

      const full_input = JSON.stringify(args);
      for (const pattern of dangerous) {
        if (pattern.test(full_input)) {
          throw new Error(
            `SECURITY: Dangerous pattern detected: ${pattern.source}`
          );
        }
      }
    }

    // Rule 2: Rate limiting per agent
    const rate_key = `agent:${agent_id}:tool:${tool}`;
    const count = await redis.incr(rate_key);
    await redis.expire(rate_key, 60);

    if (count > 100) {
      throw new Error(`Rate limit exceeded for ${tool}`);
    }

    // Rule 3: Log all risky operations
    if (['Bash', 'Edit', 'Write'].includes(tool)) {
      console.log(`[SECURITY] ${agent_id} calling ${tool}:`, args);
    }

    return context; // Allow or throw to block
  }
};

# .claude/hooks/post-execution/output-sanitizer.js
module.exports = {
  name: 'output-sanitizer',
  event: 'post-execution',
  async handler(context) {
    const { output, tool } = context;

    // Sanitize output before returning to user
    let sanitized = output;

    // Remove API keys
    sanitized = sanitized.replace(
      /sk-[\w\d]{40,}/g,
      '[ANTHROPIC_API_KEY_REDACTED]'
    );
    sanitized = sanitized.replace(
      /AKIA[\w\d]{16}/g,
      '[AWS_ACCESS_KEY_REDACTED]'
    );

    // Remove internal IPs
    sanitized = sanitized.replace(
      /192\.168\.\d{1,3}\.\d{1,3}/g,
      '[INTERNAL_IP]'
    );
    sanitized = sanitized.replace(
      /10\.\d{1,3}\.\d{1,3}\.\d{1,3}/g,
      '[INTERNAL_IP]'
    );

    // Remove credentials from connection strings
    sanitized = sanitized.replace(
      /([a-z]+):\/\/([^:]+):([^@]+)@/g,
      '$1://[USER]:[PASSWORD]@'
    );

    // Remove emails
    if (!process.env.ALLOW_EMAIL_IN_OUTPUT) {
      sanitized = sanitized.replace(
        /[\w.-]+@[\w.-]+\.\w+/g,
        '[EMAIL_REDACTED]'
      );
    }

    return { ...context, output: sanitized };
  }
};

---
# Security-focused CLAUDE.md
name: secure-agent
version: 1.0.0

# === Permission Lockdown ===
model: claude-sonnet
permission-mode: default
disallowedTools: [Bash]  # No shell!

# === Tools Whitelist ===
allowed-tools:
  - Read
  - Grep
  - Glob
  - Edit (nur für /tmp/workspace)

# === Safety Rules ===
safety-rules:
  never:
    - Execute arbitrary shell commands
    - Read files outside /data/input
    - Write to system directories
    - Make outbound network requests
    - Access credentials from environment

  always:
    - Sanitize user input
    - Check file paths
    - Log sensitive operations
    - Ask before destructive ops

# === API Key Management ===
secrets:
  location: vault  # NEVER hardcode!
  access: credentials-only
  encryption: AES-256

# === Audit & Monitoring ===
audit:
  enabled: true
  log_all_operations: true
  sensitive_operations:
    - Write
    - Edit
    - Bash
  retention: 90 days

# === Rate Limiting ===
rate_limits:
  api_calls: 1000 per hour
  file_operations: 100 per hour
  bash_commands: 0 (disabled)

# === Data Retention ===
data_retention:
  session_logs: 24 hours
  audit_logs: 90 days
  crash_dumps: 7 days
---

# FALSCH - NEVER DO THIS
OPENAI_API_KEY = "sk-proj-abc123..."
DATABASE_URL = "postgresql://user:pass@host"

# RICHTIG - Use vault
from vault import get_secret

api_key = get_secret("shared/openai/API_KEY")
db_url = get_secret("shared/database/CONNECTION_STRING")

class VaultManager:
    def __init__(self):
        self.vault = VaultClient(
            url=os.environ["VAULT_ADDR"],
            token=os.environ["VAULT_TOKEN"]
        )

    def get_credential(self, path):
        """Safely retrieve credential from vault"""
        try:
            secret = self.vault.get(f"shared/{path}")
            return secret["data"]["value"]
        except Exception as e:
            raise SecretError(f"Failed to retrieve {path}")

    def rotate_credential(self, path, new_value):
        """Update credential with audit trail"""
        self.vault.put(f"shared/{path}", {"value": new_value})
        self.log_audit(f"Credential rotated: {path}", level="CRITICAL")

    def list_credentials(self):
        """Show all accessible secrets"""
        return self.vault.list("shared/")

# Usage
vault = VaultManager()
api_key = vault.get_credential("openai/API_KEY")
db_password = vault.get_credential("database/PASSWORD")

name: Secure Claude Code Action

on:
  push:
    branches: [main, develop]

permissions:
  contents: read
  security-events: write

jobs:
  security-check:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      # Secret scanning
      - name: TruffleHog Secret Scan
        uses: trufflesecurity/trufflehog@main
        with:
          path: ./
          extra_args: --debug --json

      # Dependency scanning
      - name: Run Trivy Vulnerability Scanner
        uses: aquasecurity/trivy-action@master
        with:
          scan-type: 'fs'
          scan-ref: '.'
          format: 'sarif'
          output: 'trivy-results.sarif'

      # Upload to GitHub Security
      - name: Upload Trivy Results
        uses: github/codeql-action/upload-sarif@v2
        with:
          sarif_file: 'trivy-results.sarif'

      # Claude Code with security restrictions
      - name: Claude Code Analysis
        uses: anthropics/claude-code-action@v1
        with:
          api-key: ${{ secrets.ANTHROPIC_API_KEY }}
          model: claude-opus
          max-turns: 10
          custom-instructions: |
            Security review of this code:
            - No hardcoded credentials
            - SQL injection protection
            - OWASP Top 10 compliance
            - No sensitive data in logs

class PluginSecurityEvaluator:
    def __init__(self):
        self.risk_factors = []

    def evaluate_plugin(self, plugin_manifest):
        """Evaluate plugin for security risks"""
        scores = {
            "permissions": self._check_permissions(plugin_manifest),
            "source": self._check_source(plugin_manifest),
            "dependencies": self._check_dependencies(plugin_manifest),
            "code_review": self._check_code_review(plugin_manifest)
        }

        return self._calculate_risk_score(scores)

    def _check_permissions(self, manifest):
        """Check if plugin requests dangerous permissions"""
        dangerous_perms = ["tool:bash", "network:outbound", "credential:vault"]
        requested = manifest.get("permissions", [])
        risky = [p for p in requested if p in dangerous_perms]
        return {"risk": len(risky) * 20}  # 20 points per dangerous perm

    def _check_source(self, manifest):
        """Verify plugin comes from trusted source"""
        author = manifest.get("author")
        trusted_authors = ["anthropics", "buildwithclaude"]
        is_trusted = any(t in author.lower() for t in trusted_authors)
        return {"risk": 0 if is_trusted else 50}

    def _check_dependencies(self, manifest):
        """Check if dependencies are safe"""
        # Scan for known vulnerable packages
        deps = manifest.get("dependencies", {})
        vulnerable = ["left-pad", "event-stream"]  # Known issues
        risky_deps = [d for d in deps if d in vulnerable]
        return {"risk": len(risky_deps) * 30}

    def _check_code_review(self, manifest):
        """Check if code has been reviewed"""
        reviews = manifest.get("reviews", [])
        stars = manifest.get("rating", 0)
        downloads = manifest.get("downloads", 0)

        # More downloads + good reviews = lower risk
        review_score = (len(reviews) * 10) + (stars * 5) + (downloads / 1000)
        return {"risk": max(0, 50 - review_score)}

    def _calculate_risk_score(self, scores):
        """Aggregate risk scores"""
        total = sum(s["risk"] for s in scores.values())
        risk_level = "LOW" if total < 30 else "MEDIUM" if total < 60 else "HIGH"
        return {"total_risk": total, "level": risk_level, "scores": scores}

class EnterpriseSecurityManager:
    def __init__(self):
        self.sso_provider = "okta"  # or "azure-ad"
        self.rbac = RBACEngine()

    def setup_sso(self, config):
        """Configure SSO integration"""
        return {
            "provider": config.get("provider"),
            "client_id": config.get("client_id"),
            "client_secret": config.get("client_secret"),
            "discovery_url": config.get("discovery_url"),
            "redirect_uri": "https://claude.company.com/auth/callback"
        }

    def verify_user(self, token):
        """Verify JWT token from SSO"""
        try:
            payload = jwt.decode(
                token,
                algorithms=["RS256"],
                options={"verify_signature": True}
            )
            return payload
        except jwt.InvalidTokenError as e:
            raise AuthenticationError(f"Invalid token: {e}")

    def check_permission(self, user_id, action, resource):
        """Check RBAC permission"""
        role = self._get_user_role(user_id)
        perms = self.rbac.get_permissions(role)

        action_key = f"{action}:{resource}"
        if action_key not in perms:
            raise PermissionDenied(
                f"User {user_id} not authorized for {action_key}"
            )

    def audit_log(self, user_id, action, resource, result):
        """Log all access attempts"""
        timestamp = datetime.now().isoformat()
        log_entry = {
            "timestamp": timestamp,
            "user_id": user_id,
            "action": action,
            "resource": resource,
            "result": result,
            "ip": request.remote_addr
        }

        # Store in audit database
        self._save_to_audit_db(log_entry)

        # Alert on suspicious activity
        if result == "DENIED":
            self._check_for_attacks(user_id)

# FALSCH
api_key = "sk-proj-abc123"
requests.get(f"https://api.example.com?key={api_key}")

# RICHTIG
api_key = os.environ.get("API_KEY")
requests.get("https://api.example.com", headers={"Authorization": f"Bearer {api_key}"})

# FALSCH - Vulnerable!
query = f"SELECT * FROM users WHERE email = '{user_email}'"
db.execute(query)

# RICHTIG - Parameterized
query = "SELECT * FROM users WHERE email = %s"
db.execute(query, (user_email,))

# FALSCH - Way too open!
sandbox:
  filesystem: /
  network:
    allowed-domains: "*"

# RICHTIG - Restricted
sandbox:
  filesystem: /tmp/workspace
  network:
    allowed-domains:
      - api.trusted.com

# FALSCH
logger.info(f"User authenticated: {password}")

# RICHTIG
logger.info(f"User authenticated: {username}")