Brakeman Ruby on Rails Security Scanner Cheat Sheet

Overview

Brakeman is a static analysis security scanner specifically designed for Ruby on Rails applications. It analyzes Rails application code to find security vulnerabilities without requiring the application to be running. Brakeman is an essential tool in DevSecOps pipelines for Rails applications, helping developers identify common security issues like SQL injection, cross-site scripting (XSS), and other Rails-specific vulnerabilities early in the development process.

⚠️ Note: Brakeman is designed specifically for Ruby on Rails applications and may not work correctly with other Ruby frameworks. It should be used as part of a comprehensive security testing strategy.

Installation

Using gem

bash

# Install Brakeman gem
gem install brakeman

# Install specific version
gem install brakeman -v 5.4.1

# Install from source
git clone https://github.com/presidentbeef/brakeman.git
cd brakeman
gem build brakeman.gemspec
gem install brakeman-*.gem

# Verify installation
brakeman --version

Using Bundler

ruby

# Add to Gemfile
group :development do
  gem 'brakeman', require: false
end

# Install
bundle install

# Run via bundle
bundle exec brakeman

Using Docker

bash

# Pull official Brakeman image
docker pull presidentbeef/brakeman

# Run Brakeman in container
docker run --rm -v $(pwd):/code presidentbeef/brakeman

# Build custom image
cat > Dockerfile << 'EOF'
FROM ruby:3.0-slim
RUN gem install brakeman
WORKDIR /app
ENTRYPOINT ["brakeman"]
EOF

docker build -t custom-brakeman .
docker run --rm -v $(pwd):/app custom-brakeman

Package Managers

bash

# Ubuntu/Debian (via RubyGems)
sudo apt update
sudo apt install ruby-dev
sudo gem install brakeman

# macOS with Homebrew
brew install brakeman

# CentOS/RHEL/Fedora
sudo dnf install ruby-devel
sudo gem install brakeman

Basic Usage

Simple Scans

bash

# Scan current Rails application
brakeman

# Scan specific Rails application
brakeman /path/to/rails/app

# Scan with verbose output
brakeman -v

# Scan with debug output
brakeman -d

# Quick scan (faster, less thorough)
brakeman -q

# Scan specific files
brakeman --only-files app/controllers/users_controller.rb,app/models/user.rb

Output Formats

bash

# Default text output
brakeman

# JSON output
brakeman -f json

# HTML output
brakeman -f html

# CSV output
brakeman -f csv

# Markdown output
brakeman -f markdown

# SARIF output (for GitHub integration)
brakeman -f sarif

# Save output to file
brakeman -o brakeman-report.html -f html
brakeman -o brakeman-report.json -f json
brakeman -o brakeman-report.csv -f csv

Confidence Levels

bash

# Show only high confidence warnings
brakeman -w3

# Show high and medium confidence warnings
brakeman -w2

# Show all warnings (including low confidence)
brakeman -w1

# Default behavior (medium and high confidence)
brakeman

Configuration

Configuration File (.brakeman.yml)

yaml

# .brakeman.yml
:app_path: "."
:output_files:
  - "brakeman-report.html"
  - "brakeman-report.json"
:output_formats:
  - :html
  - :json
:quiet: false
:min_confidence: 2
:combine_locations: true
:collapse_mass_assignment: true
:highlight_user_input: true
:ignore_redirect_to_model: true
:ignore_model_output: false
:check_arguments: true
:safe_methods:
  - :sanitize
  - :h
  - :html_escape
:skip_checks:
  - :SSL
  - :LinkTo
:report_progress: true
:parallel_checks: true

Command Line Configuration

bash

# Set minimum confidence level
brakeman --confidence-level 2  # Medium and high only
brakeman --confidence-level 3  # High only

# Skip specific checks
brakeman --skip-checks SSL,LinkTo,Render

# Run only specific checks
brakeman --test SQL,XSS,Command

# Ignore specific files
brakeman --skip-files app/controllers/admin_controller.rb

# Set Rails version explicitly
brakeman --rails3
brakeman --rails4
brakeman --rails5
brakeman --rails6
brakeman --rails7

# Additional options
brakeman --no-progress        # Disable progress reporting
brakeman --no-pager          # Disable pager for output
brakeman --table-width 120   # Set table width
brakeman --url-safe-methods method1,method2  # Additional URL-safe methods

Advanced Usage

Baseline and Progressive Scanning

bash

# Create baseline
brakeman -f json -o baseline.json

# Compare against baseline
brakeman --compare baseline.json

# Ignore baseline warnings
brakeman --ignore-config baseline.ignore

# Generate ignore file from current warnings
brakeman --ignore-config brakeman.ignore --interactive-ignore

Custom Checks

ruby

# custom_check.rb
class CustomCheck < Brakeman::BaseCheck
  Brakeman::Checks.add self

  @description = "Check for custom security pattern"

  def run_check
    tracker.find_call(:target => nil, :method => :dangerous_method).each do |result|
      warn :result => result,
           :warning_type => "Custom Warning",
           :warning_code => :custom_dangerous_method,
           :message => "Avoid using dangerous_method",
           :confidence => :high
    end
  end
end

Integration with Rails

ruby

# config/brakeman.yml in Rails app
:app_path: "."
:output_files:
  - "tmp/brakeman-report.html"
:output_formats:
  - :html
:quiet: true
:min_confidence: 2

# Rake task integration
# lib/tasks/security.rake
namespace :security do
  desc "Run Brakeman security scan"
  task :scan do
    require 'brakeman'
    
    options = {
      :app_path => Rails.root.to_s,
      :output_formats => [:html, :json],
      :output_files => [
        Rails.root.join('tmp', 'brakeman-report.html').to_s,
        Rails.root.join('tmp', 'brakeman-report.json').to_s
      ],
      :quiet => false,
      :min_confidence => 2
    }
    
    tracker = Brakeman.run(options)
    
    if tracker.warnings.any?
      puts "Security warnings found! Check tmp/brakeman-report.html"
      exit 1
    else
      puts "No security warnings found."
    end
  end
end

CI/CD Integration

GitHub Actions

yaml

# .github/workflows/security.yml
name: Security Scan

on: [push, pull_request]

jobs:
  brakeman:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v3
    
    - name: Set up Ruby
      uses: ruby/setup-ruby@v1
      with:
        ruby-version: '3.0'
        bundler-cache: true
    
    - name: Install Brakeman
      run: gem install brakeman
    
    - name: Run Brakeman
      run: brakeman -f sarif -o brakeman-results.sarif
    
    - name: Upload SARIF file
      uses: github/codeql-action/upload-sarif@v2
      with:
        sarif_file: brakeman-results.sarif
    
    - name: Upload results
      uses: actions/upload-artifact@v3
      with:
        name: brakeman-report
        path: brakeman-results.sarif

GitLab CI

yaml

# .gitlab-ci.yml
stages:
  - security

brakeman:
  stage: security
  image: ruby:3.0
  before_script:
    - gem install brakeman
  script:
    - brakeman -f json -o brakeman-report.json
  artifacts:
    reports:
      sast: brakeman-report.json
    paths:
      - brakeman-report.json
    expire_in: 1 week
  allow_failure: true

Jenkins Pipeline

groovy

// Jenkinsfile
pipeline {
    agent any
    
    stages {
        stage('Security Scan') {
            steps {
                script {
                    sh 'gem install brakeman'
                    sh 'brakeman -f json -o brakeman-report.json'
                    sh 'brakeman -f html -o brakeman-report.html'
                }
            }
            post {
                always {
                    archiveArtifacts artifacts: 'brakeman-report.*', fingerprint: true
                    publishHTML([
                        allowMissing: false,
                        alwaysLinkToLastBuild: true,
                        keepAll: true,
                        reportDir: '.',
                        reportFiles: 'brakeman-report.html',
                        reportName: 'Brakeman Security Report'
                    ])
                }
                failure {
                    emailext (
                        subject: "Security Scan Failed: ${env.JOB_NAME} - ${env.BUILD_NUMBER}",
                        body: "Brakeman found security issues. Check the report for details.",
                        to: "${env.CHANGE_AUTHOR_EMAIL}"
                    )
                }
            }
        }
    }
}

CircleCI

yaml

# .circleci/config.yml
version: 2.1

jobs:
  security_scan:
    docker:
      - image: cimg/ruby:3.0
    steps:
      - checkout
      - run:
          name: Install Brakeman
          command: gem install brakeman
      - run:
          name: Run Brakeman
          command: |
            brakeman -f json -o brakeman-report.json
            brakeman -f html -o brakeman-report.html
      - store_artifacts:
          path: brakeman-report.html
      - store_artifacts:
          path: brakeman-report.json

workflows:
  version: 2
  security:
    jobs:
      - security_scan

Common Vulnerability Patterns

SQL Injection

ruby

# BAD: String interpolation in queries
User.where("name = '#{params[:name]}'")
User.find_by_sql("SELECT * FROM users WHERE id = #{params[:id]}")

# GOOD: Parameterized queries
User.where(name: params[:name])
User.where("name = ?", params[:name])
User.find_by_sql(["SELECT * FROM users WHERE id = ?", params[:id]])

Cross-Site Scripting (XSS)

erb

<!-- BAD: Unescaped output -->
<%= params[:message] %>
<%= raw user_input %>
<%= content.html_safe %>

<!-- GOOD: Escaped output (default in Rails) -->
<%= h(params[:message]) %>
<%= sanitize(user_input) %>
<%= simple_format(content) %>

Mass Assignment

ruby

# BAD: Unfiltered parameters
User.create(params[:user])
user.update_attributes(params[:user])

# GOOD: Strong parameters
def user_params
  params.require(:user).permit(:name, :email)
end

User.create(user_params)
user.update_attributes(user_params)

Command Injection

ruby

# BAD: Unescaped system calls
system("ls #{params[:directory]}")
`grep #{params[:pattern]} file.txt`

# GOOD: Escaped or parameterized calls
system("ls", params[:directory])
Open3.capture3("grep", params[:pattern], "file.txt")

Cross-Site Request Forgery (CSRF)

ruby

# BAD: Missing CSRF protection
class ApplicationController < ActionController::Base
  # protect_from_forgery commented out
end

# GOOD: CSRF protection enabled
class ApplicationController < ActionController::Base
  protect_from_forgery with: :exception
end

Automation and Scripting

Automated Security Scanner

ruby

#!/usr/bin/env ruby
# brakeman_scanner.rb

require 'brakeman'
require 'json'
require 'optparse'

class BrakemanScanner
  def initialize(app_path, options = {})
    @app_path = app_path
    @options = {
      app_path: app_path,
      quiet: true,
      min_confidence: 2,
      output_formats: [:json, :html],
      output_files: [
        File.join(app_path, 'tmp', 'brakeman-report.json'),
        File.join(app_path, 'tmp', 'brakeman-report.html')
      ]
    }.merge(options)
  end
  
  def run_scan
    puts "Running Brakeman scan on #{@app_path}..."
    
    begin
      @tracker = Brakeman.run(@options)
      generate_summary
      return @tracker.warnings.empty?
    rescue => e
      puts "Error running Brakeman: #{e.message}"
      return false
    end
  end
  
  def generate_summary
    warnings = @tracker.warnings
    
    puts "\n=== Brakeman Security Scan Summary ==="
    puts "Total warnings: #{warnings.length}"
    
    # Group by confidence
    by_confidence = warnings.group_by(&:confidence)
    puts "High confidence: #{(by_confidence[:high] || []).length}"
    puts "Medium confidence: #{(by_confidence[:medium] || []).length}"
    puts "Low confidence: #{(by_confidence[:low] || []).length}"
    
    # Group by warning type
    by_type = warnings.group_by(&:warning_type)
    puts "\nWarnings by type:"
    by_type.each do |type, type_warnings|
      puts "  #{type}: #{type_warnings.length}"
    end
    
    # Show high confidence warnings
    high_warnings = by_confidence[:high] || []
    if high_warnings.any?
      puts "\n=== High Confidence Warnings ==="
      high_warnings.each do |warning|
        puts "#{warning.file}:#{warning.line} - #{warning.warning_type}: #{warning.message}"
      end
    end
  end
  
  def save_baseline
    baseline_file = File.join(@app_path, 'brakeman.baseline')
    File.write(baseline_file, @tracker.warnings.to_json)
    puts "Baseline saved to #{baseline_file}"
  end
  
  def compare_with_baseline
    baseline_file = File.join(@app_path, 'brakeman.baseline')
    return unless File.exist?(baseline_file)
    
    baseline_warnings = JSON.parse(File.read(baseline_file))
    current_warnings = @tracker.warnings.map(&:to_hash)
    
    new_warnings = current_warnings - baseline_warnings
    fixed_warnings = baseline_warnings - current_warnings
    
    puts "\n=== Baseline Comparison ==="
    puts "New warnings: #{new_warnings.length}"
    puts "Fixed warnings: #{fixed_warnings.length}"
    
    if new_warnings.any?
      puts "\nNew warnings found:"
      new_warnings.each do |warning|
        puts "  #{warning['file']}:#{warning['line']} - #{warning['warning_type']}"
      end
    end
  end
end

# Command line interface
options = {}
OptionParser.new do |opts|
  opts.banner = "Usage: #{$0} [options] [app_path]"
  
  opts.on("-c", "--confidence LEVEL", Integer, "Minimum confidence level (1-3)") do |c|
    options[:min_confidence] = c
  end
  
  opts.on("-q", "--quiet", "Quiet mode") do
    options[:quiet] = true
  end
  
  opts.on("-b", "--baseline", "Save current scan as baseline") do
    options[:save_baseline] = true
  end
  
  opts.on("--compare", "Compare with baseline") do
    options[:compare_baseline] = true
  end
  
  opts.on("-h", "--help", "Show this help") do
    puts opts
    exit
  end
end.parse!

app_path = ARGV[0] || Dir.pwd

scanner = BrakemanScanner.new(app_path, options)
success = scanner.run_scan

if options[:save_baseline]
  scanner.save_baseline
end

if options[:compare_baseline]
  scanner.compare_with_baseline
end

exit(success ? 0 : 1)

Batch Processing Script

bash

#!/bin/bash
# batch_brakeman_scan.sh

# Configuration
RAILS_APPS_DIR="/path/to/rails/apps"
REPORTS_DIR="/path/to/reports"
DATE=$(date +%Y%m%d_%H%M%S)

# Create reports directory
mkdir -p "$REPORTS_DIR"

# Function to scan Rails app
scan_rails_app() {
    local app_path="$1"
    local app_name=$(basename "$app_path")
    local report_file="$REPORTS_DIR/${app_name}_${DATE}.json"
    local html_report="$REPORTS_DIR/${app_name}_${DATE}.html"
    
    echo "Scanning $app_name..."
    
    # Check if it's a Rails app
    if [ ! -f "$app_path/config/application.rb" ]; then
        echo "Skipping $app_name - not a Rails application"
        return
    fi
    
    # Run Brakeman scan
    cd "$app_path"
    brakeman -f json -o "$report_file" -q
    brakeman -f html -o "$html_report" -q
    
    # Check for high confidence warnings
    high_warnings=$(jq '[.warnings[] | select(.confidence == "High")] | length' "$report_file" 2>/dev/null || echo "0")
    
    if [ "$high_warnings" -gt 0 ]; then
        echo "WARNING: $app_name has $high_warnings high confidence warnings!"
        echo "$app_name" >> "$REPORTS_DIR/high_risk_apps.txt"
    fi
    
    echo "Scan completed for $app_name"
}

# Find and scan all Rails applications
find "$RAILS_APPS_DIR" -name "application.rb" -path "*/config/*" | while read -r config_file; do
    app_dir=$(dirname "$(dirname "$config_file")")
    scan_rails_app "$app_dir"
done

echo "Batch scanning completed. Reports saved to $REPORTS_DIR"

# Generate summary report
echo "=== Batch Scan Summary ===" > "$REPORTS_DIR/summary_${DATE}.txt"
echo "Scan Date: $(date)" >> "$REPORTS_DIR/summary_${DATE}.txt"
echo "Total applications scanned: $(find "$REPORTS_DIR" -name "*_${DATE}.json" | wc -l)" >> "$REPORTS_DIR/summary_${DATE}.txt"

if [ -f "$REPORTS_DIR/high_risk_apps.txt" ]; then
    echo "High risk applications: $(wc -l < "$REPORTS_DIR/high_risk_apps.txt")" >> "$REPORTS_DIR/summary_${DATE}.txt"
    echo "" >> "$REPORTS_DIR/summary_${DATE}.txt"
    echo "High risk applications:" >> "$REPORTS_DIR/summary_${DATE}.txt"
    cat "$REPORTS_DIR/high_risk_apps.txt" >> "$REPORTS_DIR/summary_${DATE}.txt"
fi

Integration with Development Tools

VS Code Integration

json

// .vscode/tasks.json
{
    "version": "2.0.0",
    "tasks": [
        {
            "label": "Brakeman Security Scan",
            "type": "shell",
            "command": "brakeman",
            "args": ["-f", "html", "-o", "tmp/brakeman-report.html"],
            "group": "test",
            "presentation": {
                "echo": true,
                "reveal": "always",
                "focus": false,
                "panel": "shared"
            },
            "problemMatcher": []
        }
    ]
}

// .vscode/settings.json
{
    "ruby.lint": {
        "brakeman": {
            "enable": true,
            "command": "brakeman"
        }
    }
}

RubyMine Integration

bash

# External tool configuration
# Program: brakeman
# Arguments: -f html -o $ProjectFileDir$/tmp/brakeman-report.html
# Working directory: $ProjectFileDir$

Guard Integration

ruby

# Guardfile
guard :brakeman, :run_on_start => true do
  watch(%r{^app/.+\.(rb|erb)$})
  watch(%r{^config/.+\.rb$})
  watch(%r{^lib/.+\.rb$})
  watch('Gemfile')
end

Best Practices

Configuration Management

yaml

# .brakeman.yml - Production configuration
:app_path: "."
:output_files:
  - "tmp/brakeman-report.html"
  - "tmp/brakeman-report.json"
:output_formats:
  - :html
  - :json
:quiet: false
:min_confidence: 2
:combine_locations: true
:collapse_mass_assignment: true
:highlight_user_input: true
:ignore_redirect_to_model: true
:ignore_model_output: false
:check_arguments: true
:safe_methods:
  - :sanitize
  - :h
  - :html_escape
  - :simple_format
:skip_checks: []
:report_progress: true
:parallel_checks: true
:absolute_paths: false
:summary_only: false

Ignore File Management

yaml

# brakeman.ignore
---
:ignored_warnings:
- :warning_type: SQL
  :fingerprint: 1234567890abcdef
  :note: "Reviewed and accepted - admin only functionality"
- :warning_type: CrossSiteScripting
  :fingerprint: abcdef1234567890
  :note: "False positive - output is properly sanitized"

Team Workflow

bash

# Makefile integration
.PHONY: security-scan
security-scan:
	@echo "Running Brakeman security scan..."
	@brakeman -q -f json -o tmp/brakeman-report.json
	@if [ -s tmp/brakeman-report.json ]; then \
		echo "Security warnings found! Check tmp/brakeman-report.html"; \
		brakeman -f html -o tmp/brakeman-report.html; \
		exit 1; \
	else \
		echo "No security warnings found."; \
	fi

.PHONY: security-baseline
security-baseline:
	@echo "Creating security baseline..."
	@brakeman -f json -o brakeman.baseline
	@echo "Baseline created. Commit brakeman.baseline to version control."

# Pre-commit hook
#!/bin/bash
# .git/hooks/pre-commit
echo "Running Brakeman security scan..."
brakeman -q --no-pager
if [ $? -ne 0 ]; then
    echo "Security issues found. Commit aborted."
    echo "Run 'brakeman' to see details or 'brakeman -I' to ignore warnings."
    exit 1
fi

Troubleshooting

Common Issues

bash

# Issue: Brakeman not detecting Rails app
# Solution: Ensure you're in Rails root directory
cd /path/to/rails/app
ls config/application.rb  # Should exist

# Issue: Too many false positives
# Solution: Use ignore file and tune confidence levels
brakeman --confidence-level 3  # High confidence only
brakeman -I  # Interactive ignore mode

# Issue: Performance issues with large apps
# Solution: Use parallel processing and skip unnecessary checks
brakeman --parallel-checks --skip-checks Render,LinkTo

# Issue: Integration with CI/CD failing
# Solution: Use appropriate exit codes and formats
brakeman -q -f json -o results.json || true

Performance Optimization

bash

# Skip time-consuming checks
brakeman --skip-checks Render,LinkTo,DetailedExceptions

# Use parallel processing
brakeman --parallel-checks

# Scan only specific directories
brakeman --only-files app/controllers/,app/models/

# Quick scan mode
brakeman -q --faster

Debugging

bash

# Debug mode
brakeman -d

# Verbose output
brakeman -v

# Show timing information
brakeman --timing

# Test specific warning types
brakeman --test SQL,XSS

Resources

This cheat sheet provides comprehensive guidance for using Brakeman to identify security vulnerabilities in Ruby on Rails applications. Always combine static analysis with other security testing methods for comprehensive coverage.

Brakeman Ruby on Rails Security Scanner Cheat Sheet ​

Overview ​

Installation ​

Using gem ​

Using Bundler ​

Using Docker ​

Package Managers ​

Basic Usage ​

Simple Scans ​

Output Formats ​

Confidence Levels ​

Configuration ​

Configuration File (.brakeman.yml) ​

Command Line Configuration ​

Advanced Usage ​

Baseline and Progressive Scanning ​

Custom Checks ​

Integration with Rails ​

CI/CD Integration ​

GitHub Actions ​

GitLab CI ​

Jenkins Pipeline ​

CircleCI ​

Common Vulnerability Patterns ​

SQL Injection ​

Cross-Site Scripting (XSS) ​

Mass Assignment ​

Command Injection ​

Cross-Site Request Forgery (CSRF) ​

Automation and Scripting ​

Automated Security Scanner ​

Batch Processing Script ​

Integration with Development Tools ​

VS Code Integration ​

RubyMine Integration ​

Guard Integration ​

Best Practices ​

Configuration Management ​

Ignore File Management ​

Team Workflow ​

Troubleshooting ​

Common Issues ​

Performance Optimization ​

Debugging ​

Resources ​

Brakeman Ruby on Rails Security Scanner Cheat Sheet

Overview

Installation

Using gem

Using Bundler

Using Docker

Package Managers

Basic Usage

Simple Scans

Output Formats

Confidence Levels

Configuration

Configuration File (.brakeman.yml)

Command Line Configuration

Advanced Usage

Baseline and Progressive Scanning

Custom Checks

Integration with Rails

CI/CD Integration

GitHub Actions

GitLab CI

Jenkins Pipeline

CircleCI

Common Vulnerability Patterns

SQL Injection

Cross-Site Scripting (XSS)

Mass Assignment

Command Injection

Cross-Site Request Forgery (CSRF)

Automation and Scripting

Automated Security Scanner

Batch Processing Script

Integration with Development Tools

VS Code Integration

RubyMine Integration

Guard Integration

Best Practices

Configuration Management

Ignore File Management

Team Workflow

Troubleshooting

Common Issues

Performance Optimization

Debugging

Resources