IaC Security Scanning Tools: Checkov, tfsec, KICS, and Snyk IaC Compared
Written by the Rafter Team
Infrastructure as code security scanning detects misconfigurations in your Terraform, CloudFormation, and Kubernetes definitions before they reach production. Without scanning, a single overly permissive IAM policy or public S3 bucket can expose your entire cloud environment. The right IaC scanner catches these issues at the pull request stage — when fixes are cheap and deployments are safe.
IaC scanning catches configuration-level issues but does not replace runtime monitoring. A Terraform plan that passes all policy checks can still be applied to an environment with drift, stale state, or manually modified resources.
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What IaC Scanners Check
IaC scanners evaluate your infrastructure definitions against policy libraries that map to CIS benchmarks, cloud provider best practices, and compliance frameworks like SOC 2 and PCI DSS. Common misconfigurations they catch include:
- Public access — S3 buckets without access restrictions, security groups open to 0.0.0.0/0, databases exposed to the internet.
- Missing encryption — EBS volumes, RDS instances, or S3 buckets without encryption at rest. Transit encryption disabled on load balancers or API gateways.
- Overprivileged IAM — wildcard actions in IAM policies, roles with administrative access, missing least-privilege boundaries.
- Logging gaps — CloudTrail disabled, VPC flow logs missing, Kubernetes audit logging not configured.
Tool Comparison
Checkov is an open-source scanner by Bridgecrew (now Palo Alto) that supports Terraform, CloudFormation, Kubernetes, Helm, and ARM templates. It ships with over 1,000 built-in policies mapped to CIS benchmarks and allows custom policies written in Python or YAML. Checkov also scans Terraform plan output, catching issues that only appear after variable interpolation.
tfsec (now part of Trivy) focuses specifically on Terraform with deep HCL parsing. It understands Terraform module references and variable resolution, which reduces false positives compared to tools that treat HCL as flat text. It is fast, produces clear output with remediation links, and integrates easily into CI pipelines.
KICS (Keeping Infrastructure as Code Secure) is an open-source tool by Checkmarx that supports the broadest range of IaC formats — Terraform, CloudFormation, Ansible, Kubernetes, Docker, and OpenAPI. Its query engine uses Rego (the same language OPA uses), making it familiar to teams already using policy-as-code workflows.
Snyk IaC extends the Snyk platform to infrastructure scanning. It covers Terraform, CloudFormation, Kubernetes, and ARM templates with a curated policy set. The commercial platform adds fix suggestions, priority scoring based on exploitability, and a unified dashboard that combines IaC findings with your application vulnerability data.
| Capability | Checkov | tfsec/Trivy | KICS | Snyk IaC |
|---|---|---|---|---|
| Terraform | Yes | Yes | Yes | Yes |
| CloudFormation | Yes | No | Yes | Yes |
| Kubernetes | Yes | Yes | Yes | Yes |
| CIS benchmarks | Built-in | Built-in | Built-in | Built-in |
| Custom policies | Python/YAML | JSON/YAML | Rego | Snyk rules |
| License | OSS | OSS | OSS | Freemium |
Choosing the Right Scanner
If your stack is Terraform-only, tfsec (via Trivy) gives you the best signal-to-noise ratio with minimal setup. For multi-format environments that mix Terraform, CloudFormation, and Kubernetes manifests, Checkov or KICS cover the broadest surface. If your organization already uses Snyk for application security, Snyk IaC consolidates your findings into a single workflow.
Regardless of which scanner you choose, run it in your CI/CD pipeline as a blocking check. IaC scanning only works when it runs on every change — not as a periodic audit.
Combine IaC Scanning with Application Security
IaC scanners secure your infrastructure layer. Your application code still needs static analysis to catch injection flaws, authentication bugs, and other vulnerabilities that live in your source code. A complete DevSecOps pipeline runs both — IaC scanning for your infrastructure and SAST for your application — so nothing ships without a security check.
Add Rafter to your pipeline for application-level security scanning