Gauntlt: Security Testing in Plain English for CI/CD Pipelines

Hook

What if your security penetration tests could be written by developers who've never touched nmap, and read by managers who've never seen a command line?

Context

In the early 2010s, DevOps teams faced a brutal reality: security testing happened at the end of the release cycle, performed by specialized security engineers using tools that developers couldn't easily integrate into their workflows. Tools like nmap, sqlmap, and nikto were powerful but required specialized knowledge. Worse, incorporating them into continuous integration pipelines meant writing custom scripts that were brittle, hard to maintain, and opaque to anyone outside the security team.

Gauntlt emerged from the Rugged DevOps movement—a philosophy that emphasized building security into software from the beginning rather than bolting it on at the end. The project's tagline, 'be mean to your code,' encapsulates its core mission: make it trivially easy to attack your own systems before attackers do. By wrapping security tools in Cucumber's Gherkin syntax, Gauntlt transformed security testing from an arcane art into something that could be versioned, reviewed, and executed alongside unit tests. It was security-as-code before that term became a buzzword.

Technical Insight

Gauntlt's architecture is deceptively simple: it's a collection of Cucumber step definitions that wrap command-line security tools. Instead of learning each tool's syntax and output parsing logic, you write .attack files using natural language scenarios. Here's what a basic port scanning attack looks like:

@slow
Feature: Run nmap against a target
  Scenario: Verify that dangerous ports are not exposed
    Given "nmap" is installed
    And the following profile:
      | name       | value           |
      | target     | 192.168.1.100   |
    When I launch a "nmap" attack with:
      """
      nmap -p 21,23,25,3389 <target> -oX -
      """
    Then the output should not contain:
      """
      21/tcp.*open
      23/tcp.*open
      3389/tcp.*open
      """

This declarative approach hides the complexity of XML parsing (nmap outputs XML with -oX) and regex matching. Under the hood, Gauntlt executes the nmap command, captures stdout, and runs the regex patterns you've defined. The 'attack adapters' are Ruby classes that know how to invoke specific tools and interpret their output formats.

The framework ships with pre-built adapters for tools like sqlmap, sslyze, arachni, and garmr, but its generic attack adapter is where the real flexibility lives. This adapter can wrap any command-line tool:

Feature: Test SSL configuration
  Scenario: Ensure TLS 1.0 is disabled
    Given "sslyze" is installed
    When I launch a "generic" attack with:
      """
      sslyze --tlsv1 example.com
      """
    Then the output should contain "TLSv1 disabled"

Gauntlt's step definitions are implemented as standard Cucumber steps. Looking at the actual Ruby code, a simplified version of the attack launch step looks like this:

When(/^I launch a "([^"]*)" attack with:$/) do |attack_adapter, attack_string|
  adapter = AttackAdapterFactory.create(attack_adapter)
  @stdout, @stderr, @status = adapter.execute(
    attack_string.gsub(/<([^>]+)>/) { @profiles[$1] }
  )
end

This reveals Gauntlt's core pattern: the framework is primarily a translation layer. It takes human-readable scenarios, interpolates variables from profile tables, shells out to external tools, and provides assertion helpers. The brilliance isn't in algorithmic complexity—it's in the interface design that makes security testing accessible.

The profile system deserves special attention. Profiles let you parameterize attacks, making them reusable across environments. You might define <target> as localhost in development but staging.example.com in your CI pipeline. This is accomplished through simple string interpolation before the command executes, but it enables powerful workflows where the same attack files run against different environments by simply swapping a YAML configuration.

Integration with CI/CD pipelines is straightforward because Gauntlt exits with standard exit codes—zero for success, non-zero for failure. Your Jenkins or GitHub Actions workflow can treat security tests identically to unit tests:

# .github/workflows/security.yml
steps:
  - name: Run Gauntlt attacks
    run: |
      bundle exec gauntlt --tags ~@slow ./attacks

The tagging system (borrowed from Cucumber) lets you mark slow attacks like full vulnerability scans with @slow and exclude them from fast feedback loops while including them in nightly security builds.

Gotcha

Gauntlt's biggest limitation is that it's only as good as the tools it wraps. If sqlmap can't detect a particular SQL injection variant, Gauntlt won't magically find it either. You're responsible for installing, configuring, and maintaining each underlying security tool. On a fresh system, getting all dependencies working—especially older tools with complex installation requirements—can be a multi-hour endeavor. The gauntlt-docker project helps, but introduces its own containerization complexity.

The project's development velocity has slowed significantly. After a 2018 relaunch, commits became sporadic, and compatibility with modern Ruby versions (3.x) and updated security tools isn't guaranteed. Some adapters may fail silently if the underlying tool changes its output format. You'll likely need to fork the project and maintain custom adapters if you're using recent versions of tools like arachni or garmr. This isn't a dealbreaker for teams with Ruby expertise, but it means you're semi-adopting an orphaned framework rather than riding a wave of active development. The community around Gauntlt has largely moved on to newer security-as-code approaches, so Stack Overflow answers and updated tutorials are scarce.

Verdict

Use Gauntlt if you're already running command-line security tools manually and want to codify those tests in a readable format that non-security engineers can understand and modify. It shines in environments where Ruby is already in the stack and you value declarative security tests over comprehensive scanning capabilities. The Gherkin syntax genuinely lowers the barrier for developers to write security tests, making it valuable for teams adopting DevSecOps practices who need security tests that can be peer-reviewed like application code. Skip it if you need a batteries-included security solution with active maintenance and modern tool support. The maintenance burden of keeping adapters working and managing dependencies outweighs the benefits unless you have Ruby expertise in-house. For greenfield projects, purpose-built platforms like Nuclei or commercial solutions like Snyk offer better tooling, active communities, and lower total cost of ownership. Gauntlt is best suited for teams already committed to the Rugged DevOps philosophy who want maximum control over their security testing workflow.