Ensure VPC subnets do not assign public IP by default

Error: VPC subnets should not allow automatic public IP assignment

Bridgecrew Policy ID: BC_AWS_NETWORKING_53
Checkov Check ID: CKV_AWS_130
Severity: MEDIUM

VPC subnets should not allow automatic public IP assignment

Description

VPC subnet is a part of the VPC having its own rules for traffic. Assigning the Public IP to the subnet automatically (on launch) can accidentally expose the instances within this subnet to internet and should be edited to 'No' post creation of the Subnet.

Fix - Buildtime

Terraform

  • Resource: aws_subnet
  • Argument: map_public_ip_on_launch
resource "aws_subnet" "test" {
 ...
+ map_public_ip_on_launch = false
  }

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