Terraform security scanning tools - Commands & Configuration

Introduction

Terraform security scanning tools help find security problems in your infrastructure code before you use it. They check your Terraform files to make sure you don't accidentally create unsafe setups.

Before applying Terraform code to production to catch security risks early.

When reviewing Terraform code written by your team to ensure it follows security rules.

To automate security checks in your code pipeline so unsafe changes are blocked.

When you want to learn about common security mistakes in Terraform configurations.

To verify compliance with company or industry security standards in infrastructure.

Config File - main.tf

main.tf

terraform {
  required_version = ">= 1.0"
}

provider "aws" {
  region = "us-east-1"
}

resource "aws_s3_bucket" "example" {
  bucket = "example-secure-bucket"
  acl    = "private"

  versioning {
    enabled = true
  }

  server_side_encryption_configuration {
    rule {
      apply_server_side_encryption_by_default {
        sse_algorithm = "AES256"
      }
    }
  }
}

This Terraform file creates an AWS S3 bucket with security best practices:

• acl = "private" keeps the bucket private.
• versioning enabled protects against accidental deletes.
• server_side_encryption_configuration encrypts data at rest.

Security scanning tools will check for these settings to ensure the bucket is secure.

Commands

This command initializes the Terraform working directory. It downloads necessary provider plugins and prepares the environment for further commands.

Terminal

terraform init

Expected Output

Initializing the backend...



Initializing provider plugins...

- Finding latest version of hashicorp/aws...

- Installing hashicorp/aws v4.0.0...

- Installed hashicorp/aws v4.0.0 (signed by HashiCorp)



Terraform has been successfully initialized!



You may now begin working with Terraform. Try running "terraform plan" to see any changes that are required for your infrastructure.

This command checks your Terraform files for syntax errors and basic correctness before applying them.

Terminal

terraform validate

Expected Output

Success! The configuration is valid.

This command initializes TFLint, a Terraform linter that can detect security and style issues in your Terraform code.

Terminal

tflint --init

Expected Output

INFO: Initializing TFLint...

INFO: Plugin aws installed

INFO: Initialization completed

This command runs TFLint to scan your Terraform files for security issues and best practice violations.

Terminal

tflint

Expected Output

No issues found!

This command runs Checkov, a security scanner for Terraform, to detect security misconfigurations in your Terraform directory.

Terminal

checkov -d .

Expected Output

Passed checks: 10, Failed checks: 0, Skipped checks: 0



Checkov scan completed successfully.

Key Concept

If you remember nothing else from this pattern, remember: always scan your Terraform code with security tools before applying it to catch risks early.

Common Mistakes

Running terraform apply without running security scans first

This can deploy insecure infrastructure that may expose data or cause outages.

Always run security scanning tools like TFLint or Checkov before applying Terraform changes.

Ignoring warnings or errors from security scanning tools

Warnings often indicate real security risks that should be fixed to protect your infrastructure.

Review and fix all security warnings before deploying your Terraform code.

Not initializing security tools before scanning

Tools like TFLint require initialization to download rules and plugins; skipping this causes scan failures.

Run initialization commands like 'tflint --init' before scanning.

Summary

Initialize Terraform and providers with 'terraform init' to prepare your environment.

Validate Terraform files with 'terraform validate' to catch syntax errors early.

Use TFLint and Checkov commands to scan Terraform code for security issues.

Fix any security warnings before applying infrastructure changes.

Practice

1. What is the main purpose of Terraform security scanning tools like tfsec?

easy

A. To monitor cloud resource usage costs

B. To deploy Terraform infrastructure automatically

C. To write Terraform code faster with autocomplete

D. To find security risks in Terraform code before deployment

Solution

1. Step 1: Understand Terraform security scanning tools

   These tools analyze Terraform code to detect potential security issues early.

2. Step 2: Compare options with tool purpose

   Only To find security risks in Terraform code before deployment matches the purpose of finding security risks before deployment.

3. Final Answer:

   To find security risks in Terraform code before deployment -> Option D

4. Quick Check:

   Security scanning = find risks [OK]

Hint: Security tools find risks in code before cloud setup [OK]

Common Mistakes:

• Confusing scanning tools with deployment tools
• Thinking scanning tools write code
• Assuming scanning tools track costs

2. Which command correctly runs tfsec to scan your Terraform project in the current folder?

easy

A. tfsec scan terraform

B. terraform scan

C. tfsec .

D. terraform tfsec run

Solution

1. Step 1: Recall tfsec usage syntax

   The correct way to run tfsec is by specifying the folder, commonly the current folder with a dot.

2. Step 2: Match command to syntax

   Only tfsec . correctly runs tfsec on the current directory.

3. Final Answer:

   tfsec . -> Option C

4. Quick Check:

   Run tfsec with folder path, dot means current folder [OK]

Hint: Run tfsec with dot for current folder scan [OK]

Common Mistakes:

• Using terraform commands instead of tfsec
• Adding extra words like 'scan' or 'run'
• Not specifying folder or using wrong syntax

3. Given this tfsec output snippet:

Warning: AWS S3 bucket is publicly accessible
  File: main.tf:12
  Severity: HIGH

What does this output mean?

medium

A. The S3 bucket in main.tf line 12 allows public access, which is risky

B. The S3 bucket is encrypted and secure

C. The S3 bucket is missing from the Terraform code

D. The S3 bucket is private and safe

Solution

1. Step 1: Interpret tfsec warning message

   The warning says the S3 bucket is publicly accessible, which means anyone can access it.

2. Step 2: Understand security implication

   Public access to S3 buckets is a high-risk security issue, so this is a warning to fix it.

3. Final Answer:

   The S3 bucket in main.tf line 12 allows public access, which is risky -> Option A

4. Quick Check:

   Public access warning = risky bucket [OK]

Hint: Warnings show risky settings like public access [OK]

Common Mistakes:

• Thinking warning means bucket is secure
• Confusing missing resource with public access
• Ignoring file and line number details

4. You ran tfsec . but got an error: command not found: tfsec. What is the most likely fix?

medium

A. Run terraform init first

B. Install tfsec on your system and ensure it's in your PATH

C. Change directory to the Terraform root folder

D. Update Terraform version to latest

Solution

1. Step 1: Understand the error meaning

   The error means the system cannot find the tfsec command, so it is not installed or not accessible.

2. Step 2: Fix by installing tfsec and adding to PATH

   Installing tfsec and ensuring the command is available in the system PATH fixes this error.

3. Final Answer:

   Install tfsec on your system and ensure it's in your PATH -> Option B

4. Quick Check:

   Command not found = install tool [OK]

Hint: Install tfsec if command not found error appears [OK]

Common Mistakes:

• Running terraform commands instead of installing tfsec
• Assuming directory change fixes command not found
• Updating Terraform version unrelated to tfsec error

5. You want to automate security scanning in your CI pipeline using tfsec. Which approach best ensures security issues are caught before deployment?

hard

A. Run tfsec . before Terraform apply and fail pipeline on warnings

B. Run tfsec . after Terraform apply to check deployed resources

C. Run terraform plan and ignore tfsec

D. Run tfsec . only on production branch merges

Solution

1. Step 1: Understand when to run security scans

   Security scanning should happen before deployment to catch issues early.

2. Step 2: Choose pipeline behavior to enforce security

   Failing the pipeline on warnings ensures no risky code is deployed.

3. Step 3: Evaluate other options

   Running after apply is too late; ignoring tfsec misses risks; scanning only production branch misses early detection.

4. Final Answer:

   Run tfsec . before Terraform apply and fail pipeline on warnings -> Option A

5. Quick Check:

   Scan before deploy and fail on warnings [OK]

Hint: Scan before deploy and fail on warnings to block risks [OK]

Common Mistakes:

• Running scans after deployment
• Ignoring tfsec in pipeline
• Scanning only production branch too late