Abstract
This article explores the implementation of Static Application Security Testing (SAST) for Infrastructure as Code (IaC) using Checkov. We demonstrate how to identify common security misconfigurations, such as publicly accessible S3 buckets, and seamlessly integrate the scanning process into a CI/CD pipeline using GitHub Actions.
What is Checkov?
Checkov is an open-source static analysis tool (maintained by Bridgecrew / Prisma Cloud) designed specifically for Infrastructure as Code.
Unlike tools aimed at application code (like Bandit for Python), Checkov scans configuration files for misconfigurations that could lead to security vulnerabilities or compliance issues.
Why use Checkov?
Built-in policies: It comes with hundreds of out-of-the-box policies covering AWS, Azure, and GCP best practices.
Multi-framework: Supports Terraform, CloudFormation, Kubernetes, Dockerfiles, Serverless, and more.
Easy integration: Runs from the command line or directly in your CI/CD pipelines.
The Scenario: Vulnerable Infrastructure
Imagine you have a Terraform file (main.tf) where you define an S3 bucket. By mistake (or for a quick test), you configure it to have public read access:
# main.tf
resource "aws_s3_bucket" "my_vulnerable_bucket" {
bucket = "my-dev-test-bucket"
acl = "public-read" # ❌ Security risk!
}
If we deploy this, anyone on the internet could access our data. Let's make our repository catch this error before it gets merged into the main branch.
Automating with GitHub Actions
The real magic happens when we integrate Checkov into our CI/CD workflow. This way, every time someone pushes code or opens a Pull Request, Checkov will analyze the infrastructure automatically.
In your repository, create a file at .github/workflows/checkov.yml and add the following:
What exactly does this workflow do?
1. Checkout: Clones your code into the GitHub Actions virtual environment.
2. Run Checkov: Uses the official Bridgecrew action. The directory: . parameter tells it to look for infrastructure files throughout the repository.
3. soft_fail: false: This is the key to DevSecOps. If Checkov finds a failing policy (like our public bucket), the pipeline will fail, preventing vulnerable code from being integrated.
Conclusion
Shifting security to the left (Shift-Left Security) by implementing SAST in your Infrastructure as Code is no longer optional. With tools like Checkov and GitHub Actions, it's a fast and highly effective process. With just a few lines of code, you can ensure your team doesn't accidentally deploy insecure configurations.
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