Git Security Checks

Git Security Checks

When to Use This Skill

Expert guidance for pre-commit security validation and secret detection using gitleaks and pre-commit hooks.

Core Expertise

• gitleaks: Scan for hardcoded secrets and credentials using regex + entropy analysis
• Pre-commit Hooks: Automated security validation before commits
• Declarative Allowlisting: Manage false positives via .gitleaks.toml configuration
• Security-First Workflow: Prevent credential leaks before they happen

Quick Security Scan (Recommended)

Run the comprehensive security scan pipeline in one command:

# Full scan: check all tracked files
bash "${CLAUDE_PLUGIN_ROOT}/skills/git-security-checks/scripts/security-scan.sh"

# Staged-only: check only files about to be committed
bash "${CLAUDE_PLUGIN_ROOT}/skills/git-security-checks/scripts/security-scan.sh" --staged-only

The script checks: gitleaks scan, sensitive file patterns, .gitignore coverage, high-entropy strings in diffs, and pre-commit hook status. See scripts/security-scan.sh for details.

Gitleaks Workflow

Initial Setup

# Install gitleaks (macOS)
brew install gitleaks

# Install gitleaks (Go)
go install github.com/gitleaks/gitleaks/v8@latest

# Install gitleaks (binary download)
# See https://github.com/gitleaks/gitleaks/releases

# Scan repository
gitleaks detect --source .

# Scan with verbose output
gitleaks detect --source . --verbose

Configuration

Create .gitleaks.toml for project-specific allowlists:

title = "Gitleaks Configuration"

[extend]
useDefault = true

[allowlist]
description = "Project-wide allowlist for false positives"
paths = [
    '''test/fixtures/.*''',
    '''.*\.test\.(ts|js)$''',
]

regexes = [
    '''example\.com''',
    '''localhost''',
    '''fake-key-for-testing''',
]

Pre-commit Scan Workflow

Run gitleaks before every commit:

# Scan for secrets in current state
gitleaks detect --source .

# Scan only staged changes (pre-commit mode)
gitleaks protect --staged

# Scan with specific config
gitleaks detect --source . --config .gitleaks.toml

Managing False Positives

Gitleaks provides three declarative methods for handling false positives:

1. Inline comments — mark specific lines:

# This line is safe
API_KEY = "fake-key-for-testing-only"  # gitleaks:allow

# Works in any language
password = "test-fixture"  # gitleaks:allow

2. Path-based exclusions — in .gitleaks.toml:

[allowlist]
paths = [
    '''test/fixtures/.*''',
    '''.*\.example$''',
    '''package-lock\.json$''',
]

3. Regex-based allowlists — for specific patterns:

[allowlist]
regexes = [
    '''example\.com''',
    '''localhost''',
    '''PLACEHOLDER''',
]

4. Per-rule allowlists — target specific detection rules:

[[rules]]
id = "generic-api-key"
description = "Generic API Key"

[rules.allowlist]
regexes = ['''test-api-key-.*''']
paths = ['''test/.*''']

Complete Pre-commit Security Flow

# 1. Scan for secrets
gitleaks protect --staged

# 2. Run all pre-commit hooks
pre-commit run --all-files --show-diff-on-failure

# 3. Stage your actual changes
git add src/file.ts

# 4. Show what's staged
git status
git diff --cached --stat

# 5. Commit if everything passes
git commit -m "feat(auth): add authentication module"

Pre-commit Hook Integration

.pre-commit-config.yaml

Example configuration with gitleaks:

repos:
  - repo: https://github.com/gitleaks/gitleaks
    rev: v8.22.1
    hooks:
      - id: gitleaks

Running Pre-commit Hooks

# Run all hooks on all files
pre-commit run --all-files

# Run all hooks on staged files only
pre-commit run

# Run specific hook
pre-commit run gitleaks

# Show diff on failure for debugging
pre-commit run --all-files --show-diff-on-failure

# Install hooks to run automatically on commit
pre-commit install

Common Secret Patterns

Gitleaks ships with 140+ built-in rules covering:

• API Keys: AWS, GitHub, Stripe, Google, Azure, etc.
• Authentication Tokens: JWT, OAuth tokens, session tokens
• Passwords: Hardcoded passwords in config files
• Private Keys: RSA, SSH, PGP private keys
• Database Credentials: Connection strings with passwords
• Generic Secrets: High-entropy strings that look like secrets

Examples of What Gets Detected

# Detected: Hardcoded API key
API_KEY = "sk_live_abc123def456ghi789"  # gitleaks:allow

# Detected: AWS credentials
aws_access_key_id = AKIAIOSFODNN7EXAMPLE  # gitleaks:allow

# Detected: Database password
DB_URL = "postgresql://user:Pa$$w0rd@localhost/db"  # gitleaks:allow

# Detected: Private key  # gitleaks:allow
-----BEGIN RSA PRIVATE KEY-----  # gitleaks:allow
MIIEpAIBAAKCAQEA...  # gitleaks:allow

Managing False Positives

Excluding Files

In .gitleaks.toml:

[allowlist]
paths = [
    '''package-lock\.json$''',
    '''.*\.lock$''',
    '''test/.*\.py$''',
]

Inline Ignore Comments

# In code, mark false positives
api_key = "test-key-1234"  # gitleaks:allow

# Works in any language comment style
password = "fake-password"  # gitleaks:allow

Security Best Practices

Never Commit Secrets

• Use environment variables: Store secrets in .env files (gitignored)
• Use secret managers: AWS Secrets Manager, HashiCorp Vault, etc.
• Use CI/CD secrets: GitHub Secrets, GitLab CI/CD variables
• Rotate leaked secrets: If accidentally committed, rotate immediately

Secrets File Management

# Example .gitignore for secrets
.env
.env.local
.env.*.local
*.pem
*.key
credentials.json
config/secrets.yml
.api_tokens

Handling Legitimate Secrets in Repo

For test fixtures or examples:

# 1. Use obviously fake values
API_KEY = "fake-key-for-testing-only"  # gitleaks:allow

# 2. Use placeholders
API_KEY = "<your-api-key-here>"  # gitleaks:allow

# 3. Add path exclusion in .gitleaks.toml for test fixtures

Emergency: Secret Leaked to Git History

If a secret is committed and pushed:

Immediate Actions

# 1. ROTATE THE SECRET IMMEDIATELY
# - Change passwords, revoke API keys, regenerate tokens
# - Do this BEFORE cleaning git history

# 2. Remove from current commit (if just committed)
git reset --soft HEAD~1
# Remove secret from files
git add .
git commit -m "fix(security): remove leaked credentials"

# 3. Force push (if not shared widely)
git push --force-with-lease origin branch-name

Full History Cleanup

# Use git-filter-repo to remove from all history
pip install git-filter-repo

# Remove specific file from all history
git filter-repo --path path/to/secret/file --invert-paths

# Remove specific string from all files
git filter-repo --replace-text <(echo "SECRET_KEY=abc123==>SECRET_KEY=REDACTED")

Prevention

# Always run security checks before committing
pre-commit run gitleaks

# Check what's being committed
git diff --cached

# Use .gitignore for sensitive files
echo ".env" >> .gitignore
echo ".api_tokens" >> .gitignore

Workflow Integration

Daily Development Flow

# Before staging any files
gitleaks protect --staged
pre-commit run --all-files

# Stage changes
git add src/feature.ts

# Final check before commit
git diff --cached  # Review changes
gitleaks protect --staged  # One more scan

# Commit
git commit -m "feat(feature): add new capability"

CI/CD Integration

# Example GitHub Actions workflow
name: Security Checks

on: [push, pull_request]

jobs:
  security:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - name: Gitleaks
        uses: gitleaks/gitleaks-action@v2
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

Troubleshooting

Too Many False Positives

# Check what rules are triggering
gitleaks detect --source . --verbose 2>&1 | head -50

# Add targeted allowlists in .gitleaks.toml
# Use path exclusions for test fixtures
# Use regex exclusions for known safe patterns
# Use inline gitleaks:allow for individual lines

Pre-commit Hook Failing

# Run pre-commit in verbose mode
pre-commit run gitleaks --verbose

# Check gitleaks config validity
gitleaks detect --source . --config .gitleaks.toml --verbose

# Update pre-commit hooks
pre-commit autoupdate

Scanning Git History

# Scan entire git history for leaked secrets
gitleaks detect --source . --log-opts="--all"

# Scan specific commit range
gitleaks detect --source . --log-opts="HEAD~10..HEAD"

# Generate JSON report
gitleaks detect --source . --report-format json --report-path gitleaks-report.json

Tools Reference

Gitleaks Commands

# Detect secrets in repository
gitleaks detect --source .

# Protect staged changes (pre-commit mode)
gitleaks protect --staged

# Scan with custom config
gitleaks detect --source . --config .gitleaks.toml

# Verbose output
gitleaks detect --source . --verbose

# JSON report
gitleaks detect --source . --report-format json --report-path report.json

# Scan git history
gitleaks detect --source . --log-opts="--all"

# Scan specific commit range
gitleaks detect --source . --log-opts="main..HEAD"

pre-commit Commands

# Install hooks
pre-commit install

# Run all hooks
pre-commit run --all-files

# Run specific hook
pre-commit run gitleaks

# Update hook versions
pre-commit autoupdate

# Uninstall hooks
pre-commit uninstall