CloudFormation Template Security

Hardcoded Secrets in Templates

The Problem

Embedding sensitive information directly in CloudFormation templates is a significant security risk. Hardcoded secrets can be easily exposed if templates are shared or stored in version control systems, potentially leading to unauthorized access and data breaches [1]

Code Examples

Bad Practice

1resource "aws_instance" "example" {
2  ami           = "ami-0c55b159cbfafe1f0"
3  instance_type = "t2.micro"
4}

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Good Practice

resource "aws_instance" "example" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t2.micro"

  tags = {
    Environment = "Production"
    Project     = "ExampleProject"
    Owner       = "DevOps Team"
    Compliance  = "PCI-DSS"
  }
}

Secure Patterns

• Use AWS Secrets Manager or Systems Manager Parameter Store to securely store sensitive information [1] [5]
• Leverage dynamic references in CloudFormation to retrieve secrets at runtime [5]
• Implement IAM roles and policies to control access to secrets and parameters [3]

Insecure Parameter Constraints

The Problem

Poorly defined parameter constraints can lead to overly permissive configurations or allow malicious input, potentially compromising the security of your infrastructure[2].

Code Examples

Bad Practice

Parameters:
  InstanceType:
    Type: String
    Default: t2.micro

‍‍

Good Practice

1Parameters:
2  InstanceType:
3    Type: String
4    Default: t2.micro
5    AllowedValues:
6      - t2.micro
7      - t2.small
8      - t2.medium
9    ConstraintDescription: Must be a valid EC2 instance type.

‍

Secure Patterns

• Define strict parameter constraints using AllowedValues, AllowedPattern, and MinLength/MaxLength properties5.
• Use ConstraintDescription to provide clear guidance on acceptable parameter values.
• Implement custom resource types for complex validation logic when necessary.

Missing NoEcho for Sensitive Parameters

The Problem

Without the NoEcho attribute, sensitive parameter values can be exposed in the AWS Management Console and API responses, increasing the risk of unauthorized access[5].

Code Examples

Bad Practice

Parameters:
  DatabasePassword:
    Type: String
    Description: Enter the database password

‍

Good Practice

Parameters:
  DatabasePassword:
    Type: String
    Description: Enter the database password
    NoEcho: true

‍

Secure Patterns

• Always use NoEcho: true for sensitive parameters like passwords and API keys5.
• Combine NoEcho with AWS Secrets Manager for enhanced security.
• Implement IAM policies to restrict access to sensitive stack information.

‍

Practical Remediation Steps

1. Immediate Actions

• Conduct a comprehensive audit of existing CloudFormation templates to identify security vulnerabilities. [8]
• Remove any hardcoded secrets from templates and replace them with secure references to AWS Secrets Manager or Parameter Store [1] [5]
• Enable AWS CloudTrail logging for CloudFormation API calls to track and audit changes. [9]
• Implement CloudFormation stack policies to prevent unauthorized modifications to critical resources. [9]

‍

2. Long-term Strategy

• Implement a IaC security solution like Gomboc AI
• Regularly update and patch CloudFormation resources to address newly discovered vulnerabilities.
• Implement drift detection and automated remediation to ensure deployed resources match their intended configurations6
• Develop and enforce organizational policies for secure CloudFormation template development, including guidelines for parameter constraints, secret management, and access control3
• Provide ongoing training and education for development and operations teams on CloudFormation security best practices and AWS security services integration3‍

By following these best practices and implementing a comprehensive security strategy, you can significantly enhance the security posture of your CloudFormation templates and the infrastructure they define. Remember that security is an ongoing process, requiring continuous monitoring, improvement, and adaptation to new threats and best practices.