Applying Checkov: Static Application Security Testing (SAST) to Infrastructure as Code with Terraform

Summary

This article explains how to apply static application security testing (SAST) to an infrastructure-as-code project using the Checkov tool in conjunction with Terraform. Through a brief practical guide, you will learn what Checkov is, how to install it, how it scans your .tf files, and what kinds of security issues it can detect before you deploy your infrastructure to the cloud. The tool is easy to use, automatable, and compatible with multiple environments, making it ideal for improving security from the early stages of development.

Introduction

Infrastructure as code (IaC) has revolutionized how we deploy cloud environments, but it has also brought new security challenges. Misconfigurations in Terraform files can expose critical vulnerabilities even before a server is launched. This is why it’s important to integrate tools that allow us to detect these issues before deployment.

In this article, we will explore how to apply a SAST tool called Checkov to analyze our infrastructure code created with Terraform. We’ll go through the installation process, how to use it in a real project, and what types of errors it can help prevent.

What is SAST and Why Apply It to IaC?

🔍 SAST = Static Application Security Testing

• Detects issues in code before execution


• In IaC (Terraform), it helps prevent misconfigurations that could create security gaps


• Part of the shift-left security strategy (security from development)

What is Checkov?

Checkov is an open-source tool developed by Bridgecrew.

🛠️ Features of Checkov

• Reviews .tf, .yaml, .json, and other IaC files


• Detects security misconfigurations (e.g., unencrypted resources, lack of authentication, open ports)


• Can be used from the command line

Installing Checkov and Example with Terraform

Here’s a step-by-step guide to getting Checkov up and running with Terraform.

Step 1: Install Checkov

Run the following command:

pip install checkov 

Step 2: Create or Use a Test Terraform Project

Example code for the main.tf file:

resource "aws_s3_bucket" "example" {  

  bucket = "my-test-bucket"  

  acl    = "public-read"  

}

Step 3: Run Checkov

To scan the Terraform configuration, use the following command:

checkov -d . 

Advantages and Disadvantages of Using Checkov

Advantages

✅ Easy to Use

✅ Compatible with Multiple IaC Tools

✅ Clear Reports

✅ Prevents Configuration Errors Before Deployment

Disadvantages

❌ Does not detect logic errors (only configuration issues)

❌ Some rules may be too strict

Conclusion

Applying Checkov to our Terraform projects ensures that our infrastructure adheres to good security practices from the beginning. It’s a lightweight tool that’s easy to integrate into any project. I recommend adding it to CI/CD pipelines to automatically detect errors before deployment.

References

• Bridgecrew. (n.d.). Checkov. Checkov.io. Retrieved April 19, 2025, from Checkov.io


• Source Code Analysis Tools. (n.d.). Owasp.org. Retrieved April 19, 2025, from OWASP


• Terraform. (n.d.). Terraform | HashiCorp Developer. Retrieved April 19, 2025, from Terraform