Lambda functions should restrict public URL¶

This control verifies that the Lambda function does not have a publicly accessible URL. Exposing services publicly could potentially make sensitive data accessible to malicious actors.

How to fix¶

Attribute authorization_type of aws_lambda_function_url must be "AWS_IAM".

Implementation options¶

Choose the option that matches how you manage Terraform. All options satisfy this control.

Option 1: Open source module (terraform-aws-modules)¶

If you use terraform-aws-modules/lambda/aws, configure the required module inputs to satisfy this control. You can later migrate to the compliance.tf module with minimal changes because it is compatible by design.

module "lambda" {
  source  = "terraform-aws-modules/lambda/aws"
  version = ">=8.0.0"

  create_package         = false
  function_name          = "abc123"
  handler                = "index.lambda_handler"
  local_existing_package = "lambda_function.zip"
  runtime                = "python3.12"

  authorization_type = "AWS_IAM"
}

Option 2: Terraform AWS provider resources¶

If you manage resources directly, configure the relevant Terraform AWS provider resources to meet this control. See docs for the resources involved: aws_lambda_function_url.

resource "aws_lambda_function" "this" {
  function_name    = "example-abc123"
  role             = "arn:aws:iam::123456789012:role/example-role"
  runtime          = "python3.12"
  handler          = "index.handler"
  filename         = "lambda_function.zip"
  source_code_hash = "base64encodedhashabcdef1234567890=="
}

resource "aws_lambda_function_url" "this" {
  function_name = "example-function"

  authorization_type = "AWS_IAM"
}

Tool mappings¶

Use these identifiers to cross-reference this control across tools, reports, and evidence.

• Compliance.tf (CTF) Control: lambda_function_restrict_public_url

• Checkov Check: CKV_AWS_301

• Powerpipe Control: aws_compliance.control.lambda_function_restrict_public_url