Securely Provisioning AWS Resources with Terraform: Best Practices and Tips
In today's cloud-driven world, security is paramount. Using Infrastructure as Code (IaC) tools like Terraform allows teams to efficiently manage AWS resources. However, securing these resources from inception is crucial. This blog will cover best practices for creating AWS resources securely with Terraform, along with links to relevant documentation, research, and tools.
Implement Least Privilege Access with IAM
Principle: Apply the least privilege principle by granting only necessary permissions to Terraform and other AWS users or services.
Use IAM Roles: Avoid using long-term credentials. Instead, configure IAM roles that assume temporary permissions. This minimizes the risk associated with leaked keys.
Environment-Specific Roles: Different environments (like development, staging, and production) should have distinct roles with relevant permissions.
Resources
AWS IAM Best Practices
AWS Roles and Policies in terraform
Encrypt Data at Rest and In Transit
Enable encryption for resources such as S3 buckets, RDS instances, and EBS volumes using AWS KMS keys.
Configure services like Amazon S3 to require HTTPS for secure data transmission, ensuring encryption in transit.
Resources
AWS S3 Encryption
Terraform KMS Resource
Securely Manage Terraform State Files
Terraform state files contain critical information about your infrastructure. Keeping these files secure is essential.
Use Remote Backends: Store state files remotely, preferably on Amazon S3, and enable state locking with DynamoDB to prevent concurrent modifications.
Encrypt the State: Ensure S3 buckets used for state storage are encrypted, both at rest and in transit.
Limit Access: Restrict access to the S3 bucket holding the state file to only those who absolutely need it.
Resources
Terraform Backend Configuration
AWS DynamoDB State Locking
Manage Secrets Securely
Avoid Hardcoding Secrets: Instead of placing sensitive values in plain text, use a secure secrets management solution.
Use AWS Secrets Manager or SSM Parameter Store: Both services integrate with Terraform to safely manage sensitive information.
Resources
AWS Secrets Manager
Terraform AWS Secrets Manager Resource
Apply Fine-Grained Access with Resource Policies
Use S3 Bucket Policies: Limit access to S3 buckets by IP range, user identity, or VPC endpoints, and disable public access for sensitive buckets.
Restrict Public Access: Ensure that only necessary resources, such as public-facing load balancers, are accessible from the internet.
Resources
AWS Identity-Based Policies
Terraform S3 Bucket Policy
Network Security: Security Groups and Network ACLs
Define security group and network ACL rules to control both inbound and outbound traffic, allowing only required IP ranges and protocols.Also, place sensitive resources in private subnets, accessible only through bastion hosts or VPN.
Resources
Amazon VPC Best Practices
Terraform VPC Module
Enable Monitoring and Logging
Enable AWS CloudTrail: Track all API actions related to AWS resources. This logging provides an audit trail and can help identify unauthorized access.
Use CloudWatch for Alerts: Set up monitoring and alerts to detect unusual activity or potential security incidents.
Resources
AWS CloudTrail Best Practices
Terraform CloudWatch Logs
Compliance Monitoring with AWS Config
AWS Config: Use AWS Config to evaluate resource configurations and monitor compliance with security best practices and regulations.
Terraform Security Tools: Integrate tools like tflint, terrascan, or tfsec to analyze Terraform code for potential security issues before deployment.
Resources
AWS Config
Terrascan for IaC Security
Follow Infrastructure as Code (IaC) Best Practices
Version Control: Track Terraform files in Git, allowing for audit trails and change history.
Separate Environments: Use workspaces or separate configurations for different environments (e.g., development, testing, production) to avoid cross-environment changes.
Lock Modules and Providers: Pin specific versions of Terraform modules and providers to prevent unexpected behavior from updates.
Resources
Terraform Best Practices for Version Control
Terraform Workspaces
Regularly Rotate Access Keys and Audit Permissions
Audit IAM Policies: Routinely review IAM policies and remove unused permissions.
Rotate Keys and Credentials: Regularly rotate access keys for users and services, and use automated rotation for credentials stored in AWS Secrets Manager.
Resources
Best Practices for IAM Key Rotation
AWS Secrets Manager Automatic Rotation
Conclusion
Securing AWS resources managed by Terraform involves a combination of AWS security best practices and Terraform-specific configurations. From implementing least privilege with IAM to securely managing state files and enforcing strict network policies, each step plays a role in safeguarding your infrastructure. By using Terraform and AWS Config rules, along with automated security tools, you can reduce the risk of misconfigurations and maintain compliance.
