Chapter 8 — Infrastructure as Code (IaC) Security

8.1 IaC Security Fundamentals

Why IaC Matters for Security

Traditional vs. IaC Security

Aspect	Traditional Security	IaC Security
Configuration	Manual, error-prone	Automated, consistent
Compliance	Periodic audits	Continuous validation
Drift Detection	Manual checks	Automated monitoring
Change Management	Change approval boards	Code review + PR workflow
Reproducibility	Variable	Guaranteed

Security Benefits of IaC

• Version Control: All changes tracked and auditable
• Peer Review: Security experts review infrastructure changes
• Automated Testing: Security checks before deployment
• Consistency: Same security controls across environments
• Speed: Rapid deployment without sacrificing security

8.2 Security Tooling for IaC

Terraform Security Tools

tfsec Integration

terraform_security_pipeline:
  tools:
    - name: "tfsec"
      purpose: "Static analysis of Terraform code"
      integration: "pre-commit hook"
      config:
        exclude_checks: ["GEN001", "AWS002"]
        severity_threshold: "HIGH"

    - name: "checkov"
      purpose: "Policy as code validation"
      integration: "CI/CD pipeline"
      policies:
        - "CIS_AWS_Foundations"
        - "NIST_800_53"
        - "Custom_Company_Policies"

  security_policies:
    - enforce_MFA_on_root_account
    - encrypt_S3_buckets
    - restrict_SG_ports
    - use_CMK_for_encryption

OPA Policy Integration

package terraform.security

# Deny S3 buckets without encryption
deny_s3_encryption[resource] {
    input.resources[_].type == "aws_s3_bucket"
    not input.resources[_].values.server_side_encryption_configuration
    resource := input.resources[_].name
}

# Deny security groups with open SSH
deny_open_ssh[resource] {
    input.resources[_].type == "aws_security_group"
    sg := input.resources[_].values
    sg.ingress[_].from_port == 22
    sg.ingress[_].cidr_blocks[_] == "0.0.0.0/0"
    resource := input.resources[_].name
}

CloudFormation Security

Template Validation

CloudFormationSecurity:
  Cfn_Nag:
    enabled: true
    fail_on_warnings: true
    rules:
      - "W33: No IAM policy wildcard actions"
      - "W5: IAM user should not have access keys"
      - "W9: Encrypted S3 bucket"
      - "W41: Security groups should not allow ingress 0.0.0.0/0"

  Guard_Rules:
    - name: "check_encrypted_volumes"
      definition: |
        Rule check_encrypted_volumes {
          %AWS::EC2::Volume.Encrypted == true
        }

    - name: "check_public_buckets"
      definition: |
        Rule check_public_buckets {
          %AWS::S3::Bucket.AccessControl != "PublicRead"
          %AWS::S3::Bucket.AccessControl != "PublicReadWrite"
        }

8.3 Automated Security Guardrails

Pre-deployment Security Checks

Comprehensive Security Pipeline

SecurityPipeline:
  Stages:
    - name: "lint_and_format"
      tools: ["terraform fmt", "tflint"]
      required: true

    - name: "dependency_scan"
      tools: ["terraform-graph", "checkov"]
      focus: "Outdated_providers_vulnerabilities"

    - name: "static_analysis"
      tools: ["tfsec", "cfn-nag"]
      threshold: "fail_on_high_critical"

    - name: "compliance_validation"
      tools: ["opa", "custom_policies"]
      frameworks: ["SOC2", "ISO27001", "PCI_DSS"]

    - name: "infrastructure_testing"
      tools: ["terratest", "kitchen-terraform"]
      tests: ["security_scenarios", "access_controls"]

    - name: "drift_detection"
      tools: ["terraform plan"]
      check: "unexpected_security_changes"

  Approval_Gates:
    - Security_Team_Review
    - Architecture_Approval
    - Compliance_Signoff

Real-time Security Monitoring

Drift Detection and Alerting

DriftDetection:
  ContinuousMonitoring:
    - Schedule: "Hourly"
    - Scope: "All_production_resources"
    - Tooling: "CloudFormation_Drift_Detection"

  Alerting:
    HighPriority:
      - Security_group_changes
      - IAM_role_modifications
      - Encryption_status_changes
      - Network_route_modifications

    MediumPriority:
      - Storage_class_changes
      - Backup_configuration_changes
      - Logging_configuration_changes

  Remediation:
    Automatic:
      - Tag_standardization
      - Naming_convention_correction

    Manual:
      - Security_group_rule_review
      - IAM_permission_analysis
      - Encryption_key_rotation

Security Policy as Code

Central Policy Repository

PolicyRepository:
  Structure:
    policies/
      iam/
        least_privilege.yaml
        mfa_requirements.yaml
        access_reviews.yaml
      network/
        security_groups.yaml
        vpc_design.yaml
        flow_logging.yaml
      data/
        encryption_standards.yaml
        backup_requirements.yaml
        data_classification.yaml
      compute/
        ami_hardening.yaml
        instance_profiles.yaml
        monitoring_requirements.yaml

  Policy_Lifecycle:
    - Creation: "Security_team_draft"
    - Review: "Architecture_and_compliance_review"
    - Approval: "CISO_approval"
    - Publication: "Documentation_and_training"
    - Enforcement: "Automated_tooling_integration"
    - Maintenance: "Quarterly_reviews_and_updates"

IaC security transforms infrastructure security from a reactive, manual process to a proactive, automated practice. By embedding security into the infrastructure development lifecycle, organizations can achieve consistent, scalable, and auditable security controls across their entire cloud environment.