EC2 Instance Has Public IP

• Query id: 5a2486aa-facf-477d-a5c1-b010789459ce
• Query name: EC2 Instance Has Public IP
• Platform: Terraform
• Severity: Medium
• Category: Networking and Firewall
• URL: Github

Description

EC2 Instance should not have a public IP address.
Documentation

Code samples

Code samples with security vulnerabilities

Positive test num. 1 - tf file

data "aws_ami" "ubuntu1" {
  most_recent = true

  filter {
    name   = "name"
    values = ["ubuntu/images/hvm-ssd/ubuntu-focal-20.04-amd64-server-*"]
  }

  filter {
    name   = "virtualization-type"
    values = ["hvm"]
  }

  owners = ["099720109477"] # Canonical
}

resource "aws_instance" "web2" {
  ami           = data.aws_ami.ubuntu.id
  instance_type = "t3.micro"

  tags = {
    Name = "HelloWorld"
  }
}

resource "aws_instance" "web3" {
  ami           = data.aws_ami.ubuntu.id
  associate_public_ip_address = true
  instance_type = "t3.micro"

  tags = {
    Name = "HelloWorld"
  }
}

Positive test num. 2 - tf file

module "ec2_instance" {
  source  = "terraform-aws-modules/ec2-instance/aws"
  version = "~> 3.0"

  name = "single-instance"

  ami                    = "ami-ebd02392"
  instance_type          = "t2.micro"
  key_name               = "user1"
  monitoring             = true
  vpc_security_group_ids = ["sg-12345678"]
  subnet_id              = "subnet-eddcdzz4"

  tags = {
    Terraform   = "true"
    Environment = "dev"
  }
}

Positive test num. 3 - tf file

module "ec2_instance" {
  source  = "terraform-aws-modules/ec2-instance/aws"
  version = "~> 3.0"

  name = "single-instance"

  ami                    = "ami-ebd02392"
  instance_type          = "t2.micro"
  key_name               = "user1"
  monitoring             = true
  vpc_security_group_ids = ["sg-12345678"]
  subnet_id              = "subnet-eddcdzz4"
  associate_public_ip_address = true

  tags = {
    Terraform   = "true"
    Environment = "dev"
  }
}

Code samples without security vulnerabilities

Negative test num. 1 - tf file

data "aws_ami" "ubuntu" {
  most_recent = true

  filter {
    name   = "name"
    values = ["ubuntu/images/hvm-ssd/ubuntu-focal-20.04-amd64-server-*"]
  }

  filter {
    name   = "virtualization-type"
    values = ["hvm"]
  }

  owners = ["099720109477"] # Canonical
}

resource "aws_instance" "web" {
  ami           = data.aws_ami.ubuntu.id
  associate_public_ip_address = false
  instance_type = "t3.micro"

  tags = {
    Name = "HelloWorld"
  }
}

Negative test num. 2 - tf file

module "ec2_instance" {
  source  = "terraform-aws-modules/ec2-instance/aws"
  version = "~> 3.0"

  name = "single-instance"

  ami                    = "ami-ebd02392"
  instance_type          = "t2.micro"
  key_name               = "user1"
  monitoring             = true
  vpc_security_group_ids = ["sg-12345678"]
  subnet_id              = "subnet-eddcdzz4"
  associate_public_ip_address = false

  tags = {
    Terraform   = "true"
    Environment = "dev"
  }
}

Negative test num. 3 - tf file

module "ec2_instance" {
  source  = "terraform-aws-modules/ec2-instance/aws"
  version = "~> 3.0"

  name = "single-instance"

  ami                    = "ami-ebd02392"
  instance_type          = "t2.micro"
  key_name               = "user1"
  monitoring             = true
  vpc_security_group_ids = ["sg-12345678"]
  subnet_id              = "subnet-eddcdzz4"

  network_interface {
    network_interface_id = aws_network_interface.this.id
    device_index         = 0
  }

  tags = {
    Terraform   = "true"
    Environment = "dev"
  }
}

resource "aws_network_interface" "this" {
  subnet_id       = var.private_subnet_id
  security_groups = [aws_security_group.this.id]
}

resource "aws_security_group" "this" {
  name        = "example"
  description = "Example Security Group"
}