VPC Peering Route Table with Unrestricted CIDR

• Query id: b3a41501-f712-4c4f-81e5-db9a7dc0e34e
• Query name: VPC Peering Route Table with Unrestricted CIDR
• Platform: Terraform
• Severity: High
• Category: Networking and Firewall
• URL: Github

Description

VPC Peering Route Table should restrict CIDR
Documentation

Code samples

Code samples with security vulnerabilities

Positive test num. 1 - tf file

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "<= 3.49.0"
    }
  }
}

provider "aws" {
  region = "us-east-1"
}

variable vpc_1_cidr_block {
  type        = string
  default     = "10.0.0.0/16"
  description = "vpc default CIDR block"
}

variable vpc_2_cidr_block {
  type        = string
  default     = "10.2.0.0/16"
  description = "vpc default CIDR block"
}

variable vpc_cidr_public_block {
  type        = string
  default     = "10.0.1.0/24"
  description = "public CIDR block"
}

variable vpc_cidr_private_block {
  type        = string
  default     = "10.0.2.0/24"
  description = "private CIDR block"
}

resource "aws_vpc" "vpc1" {
  cidr_block = var.vpc_1_cidr_block

  tags = {
    Name = "tf-test-vpc-1"
    Project = "CIS Certification"
  }
}

resource "aws_subnet" "public" {
  vpc_id            = aws_vpc.vpc1.id
  cidr_block        = var.vpc_cidr_public_block
  availability_zone = "us-east-1a"

  tags = {
    Name    = "public-subnet-1"
    Project = "CIS Certification"
  }
}

resource "aws_subnet" "private" {
  vpc_id            = aws_vpc.vpc1.id
  cidr_block        = var.vpc_cidr_private_block
  availability_zone = "us-east-1a"

  tags = {
    Name    = "private-subnet-1"
    Project = "CIS Certification"
  }
}

resource "aws_vpc" "vpc2" {
  cidr_block = var.vpc_2_cidr_block

  tags = {
    Name = "tf-test-vpc-2"
    Project = "CIS Certification"
  }
}

resource "aws_internet_gateway" "igw" {
  vpc_id                  = aws_vpc.vpc1.id

  tags                    = {
    Name                  = "igw"
    Project               = "CIS Certification"
  }
}

resource "aws_eip" "nat" {}

resource "aws_nat_gateway" "nat" {
  allocation_id          = aws_eip.nat.id
  subnet_id              = aws_subnet.public.*.id[0]

  tags                   = {
    Name                 = "nat"
    Project              = "CIS Certification"
  }

  depends_on             = [aws_internet_gateway.igw]
}

data "aws_caller_identity" "current" {}

resource "aws_vpc_peering_connection" "my_peering" {
  peer_owner_id = data.aws_caller_identity.current.account_id
  peer_vpc_id   = aws_vpc.vpc1.id
  vpc_id        = aws_vpc.vpc2.id
  auto_accept   = true

  tags = {
    Name = "VPC Peering between vpc1 and vpc2"
    Project = "CIS Certification"
  }
}

resource "aws_route_table" "public_route_table" {
  vpc_id = aws_vpc.vpc1.id

  route {
    cidr_block                  = "0.0.0.0/0"
    vpc_peering_connection_id   = aws_vpc_peering_connection.my_peering.id
  }

  tags = {
    Name = "public_route_table"
    Project = "CIS Certification"
  }
}

resource "aws_route_table" "private_route_table" {
  vpc_id = aws_vpc.vpc1.id

  route {
    cidr_block                  = aws_vpc.vpc2.cidr_block
    vpc_peering_connection_id   = aws_vpc_peering_connection.my_peering.id
  }

  tags = {
    Name = "private_route_table"
    Project = "CIS Certification"
  }
}

resource "aws_route_table_association" "private_route_table_association" {
  subnet_id      = aws_subnet.private.id
  route_table_id = aws_route_table.private_route_table.id
}

Positive test num. 2 - tf file

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "<= 3.49.0"
    }
  }
}

provider "aws" {
  region = "us-east-1"
}

variable vpc_1_cidr_block {
  type        = string
  default     = "10.0.0.0/16"
  description = "vpc default CIDR block"
}

variable vpc_2_cidr_block {
  type        = string
  default     = "10.2.0.0/16"
  description = "vpc default CIDR block"
}

variable vpc_cidr_public_block {
  type        = string
  default     = "10.0.1.0/24"
  description = "public CIDR block"
}

variable vpc_cidr_private_block {
  type        = string
  default     = "10.0.2.0/24"
  description = "private CIDR block"
}

resource "aws_vpc" "vpc1" {
  cidr_block = var.vpc_1_cidr_block
  tags = {
    Name = "tf-test-vpc-2"
    Project = "CIS Certification"
  }
}

resource "aws_subnet" "public" {
  vpc_id            = aws_vpc.vpc1.id
  cidr_block        = var.vpc_cidr_public_block
  availability_zone = "us-east-1a"


  tags = {
    Name    = "public-subnet-1"
    Project = "CIS Certification"
  }
}

resource "aws_subnet" "private" {
  vpc_id            = aws_vpc.vpc1.id
  cidr_block        = var.vpc_cidr_private_block
  availability_zone = "us-east-1a"

  tags = {
    Name    = "private-subnet-1"
    Project = "CIS Certification"
  }
}

resource "aws_vpc" "vpc2" {
  cidr_block = var.vpc_2_cidr_block
  tags = {
    Name = "tf-test-vpc-2"
    Project = "CIS Certification"
  }
}

resource "aws_internet_gateway" "igw" {
  vpc_id                  = aws_vpc.vpc1.id

  tags                    = {
    Name                  = "igw"
    Project               = "CIS Certification"
  }
}

resource "aws_eip" "nat" {}

resource "aws_nat_gateway" "nat" {
  allocation_id          = aws_eip.nat.id
  subnet_id              = aws_subnet.public.*.id[0]

  tags                   = {
    Name                 = "nat"
    Project              = "CIS Certification"
  }

  depends_on             = [aws_internet_gateway.igw]
}

data "aws_caller_identity" "current" {}

resource "aws_vpc_peering_connection" "my_peering" {
  peer_owner_id = data.aws_caller_identity.current.account_id
  peer_vpc_id   = aws_vpc.vpc1.id
  vpc_id        = aws_vpc.vpc2.id
  auto_accept   = true

  tags = {
    Name = "VPC Peering between vpc1 and vpc2"
    Project = "CIS Certification"
  }
}


resource "aws_route_table" "public_route_table9" {
  vpc_id = aws_vpc.vpc1.id

  tags = {
    Name = "public-route-table"
    Project = "CIS Certification"
  }
}

resource "aws_route_table" "private_route_table" {
  vpc_id = aws_vpc.vpc1.id

  tags = {
    Project = "CIS Certification"
  }
}

resource "aws_route" "private_route2" {
  route_table_id            = aws_route_table.public_route_table9.id
  destination_cidr_block    = "0.0.0.0/0"
  vpc_peering_connection_id = aws_vpc_peering_connection.my_peering.id
  depends_on                = [aws_route_table.public_route_table9]
}

resource "aws_route_table_association" "private_route_table_association" {
  subnet_id      = aws_subnet.private.*.id[0]
  route_table_id = aws_route_table.private_route_table.id
}

Positive test num. 3 - tf file

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 3.55.0"
    }
  }
}

provider "aws" {
  region = "us-east-1"
}

variable vpc_1_cidr_block {
  type        = string
  default     = "10.0.0.0/16"
  description = "vpc default CIDR block"
}

variable vpc_2_cidr_block {
  type        = string
  default     = "10.2.0.0/16"
  description = "vpc default CIDR block"
}

variable vpc_cidr_public_block {
  type        = string
  default     = "10.0.1.0/24"
  description = "public CIDR block"
}

variable vpc_cidr_private_block {
  type        = string
  default     = "10.0.2.0/24"
  description = "private CIDR block"
}

resource "aws_vpc" "vpc1" {
  cidr_block = var.vpc_1_cidr_block

  tags = {
    Name = "tf-test-vpc-1"
    Project = "CIS Certification"
  }
}

resource "aws_subnet" "public" {
  vpc_id            = aws_vpc.vpc1.id
  cidr_block        = var.vpc_cidr_public_block
  availability_zone = "us-east-1a"

  tags = {
    Name    = "public-subnet-1"
    Project = "CIS Certification"
  }
}

resource "aws_subnet" "private" {
  vpc_id            = aws_vpc.vpc1.id
  cidr_block        = var.vpc_cidr_private_block
  availability_zone = "us-east-1a"

  tags = {
    Name    = "private-subnet-1"
    Project = "CIS Certification"
  }
}

resource "aws_vpc" "vpc2" {
  cidr_block = var.vpc_2_cidr_block

  tags = {
    Name = "tf-test-vpc-2"
    Project = "CIS Certification"
  }
}

resource "aws_internet_gateway" "igw" {
  vpc_id                  = aws_vpc.vpc1.id

  tags                    = {
    Name                  = "igw"
    Project               = "CIS Certification"
  }
}

resource "aws_eip" "nat" {}

resource "aws_nat_gateway" "nat" {
  allocation_id          = aws_eip.nat.id
  subnet_id              = aws_subnet.public.*.id[0]

  tags                   = {
    Name                 = "nat"
    Project              = "CIS Certification"
  }

  depends_on             = [aws_internet_gateway.igw]
}

data "aws_caller_identity" "current" {}

resource "aws_vpc_peering_connection" "my_peering" {
  peer_owner_id = data.aws_caller_identity.current.account_id
  peer_vpc_id   = aws_vpc.vpc1.id
  vpc_id        = aws_vpc.vpc2.id
  auto_accept   = true

  tags = {
    Name = "VPC Peering between vpc1 and vpc2"
    Project = "CIS Certification"
  }
}

resource "aws_route_table" "public_route_table" {
  vpc_id = aws_vpc.vpc1.id

  route = [

    {
      cidr_block                 = "0.0.0.0/0"
      vpc_peering_connection_id  = aws_vpc_peering_connection.my_peering.id
      gateway_id                 = ""
      instance_id                = ""
      ipv6_cidr_block            = ""
      egress_only_gateway_id     = ""
      nat_gateway_id             = ""
      network_interface_id       = ""
      transit_gateway_id         = ""
      carrier_gateway_id         = ""
      destination_prefix_list_id = ""
      local_gateway_id           = ""
      vpc_endpoint_id            = ""

    }
  ]


  tags = {
    Name = "public_route_table"
    Project = "CIS Certification"
  }
}

resource "aws_route_table" "private_route_table" {
  vpc_id = aws_vpc.vpc1.id

  route {
    cidr_block                  = aws_vpc.vpc2.cidr_block
    vpc_peering_connection_id   = aws_vpc_peering_connection.my_peering.id
  }

  tags = {
    Name = "private_route_table"
    Project = "CIS Certification"
  }
}

resource "aws_route_table_association" "private_route_table_association" {
  subnet_id      = aws_subnet.private.id
  route_table_id = aws_route_table.private_route_table.id
}

Code samples without security vulnerabilities

Negative test num. 1 - tf file

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "<= 3.49.0"
    }
  }
}

provider "aws" {
  region = "us-east-1"
}

variable vpc_1_cidr_block {
  type        = string
  default     = "10.0.0.0/16"
  description = "vpc default CIDR block"
}

variable vpc_2_cidr_block {
  type        = string
  default     = "10.2.0.0/16"
  description = "vpc default CIDR block"
}

variable vpc_cidr_public_block {
  type        = string
  default     = "10.0.1.0/24"
  description = "public CIDR block"
}

variable vpc_cidr_private_block {
  type        = string
  default     = "10.0.2.0/24"
  description = "private CIDR block"
}

resource "aws_vpc" "vpc1" {
  cidr_block = var.vpc_1_cidr_block

  tags = {
    Name = "tf-test-vpc-1"
    Project = "CIS Certification"
  }
}

resource "aws_subnet" "public" {
  vpc_id            = aws_vpc.vpc1.id
  cidr_block        = var.vpc_cidr_public_block
  availability_zone = "us-east-1a"

  tags = {
    Name    = "public-subnet-1"
    Project = "CIS Certification"
  }
}

resource "aws_subnet" "private" {
  vpc_id            = aws_vpc.vpc1.id
  cidr_block        = var.vpc_cidr_private_block
  availability_zone = "us-east-1a"

  tags = {
    Name    = "private-subnet-1"
    Project = "CIS Certification"
  }
}

resource "aws_vpc" "vpc2" {
  cidr_block = var.vpc_2_cidr_block

  tags = {
    Name = "tf-test-vpc-2"
    Project = "CIS Certification"
  }
}

resource "aws_internet_gateway" "igw" {
  vpc_id                  = aws_vpc.vpc1.id

  tags                    = {
    Name                  = "igw"
    Project               = "CIS Certification"
  }
}

resource "aws_eip" "nat" {}

resource "aws_nat_gateway" "nat" {
  allocation_id          = aws_eip.nat.id
  subnet_id              = aws_subnet.public.*.id[0]

  tags                   = {
    Name                 = "nat"
    Project              = "CIS Certification"
  }

  depends_on             = [aws_internet_gateway.igw]
}

data "aws_caller_identity" "current" {}

resource "aws_vpc_peering_connection" "my_peering" {
  peer_owner_id = data.aws_caller_identity.current.account_id
  peer_vpc_id   = aws_vpc.vpc1.id
  vpc_id        = aws_vpc.vpc2.id
  auto_accept   = true

  tags = {
    Name = "VPC Peering between vpc1 and vpc2"
    Project = "CIS Certification"
  }
}

resource "aws_route_table" "public_route_table" {
  vpc_id = aws_vpc.vpc1.id

  route {
    cidr_block                  = "10.0.0.0/8"
    vpc_peering_connection_id   = aws_vpc_peering_connection.my_peering.id
  }

  tags = {
    Name = "public_route_table"
    Project = "CIS Certification"
  }
}

resource "aws_route_table" "private_route_table" {
  vpc_id = aws_vpc.vpc1.id

  route {
    cidr_block                  = aws_vpc.vpc2.cidr_block
    vpc_peering_connection_id   = aws_vpc_peering_connection.my_peering.id
  }

  tags = {
    Name = "private_route_table"
    Project = "CIS Certification"
  }
}

resource "aws_route_table_association" "private_route_table_association" {
  subnet_id      = aws_subnet.private.id
  route_table_id = aws_route_table.private_route_table.id
}

Negative test num. 2 - tf file

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "<= 3.49.0"
    }
  }
}

provider "aws" {
  region = "us-east-1"
}

variable vpc_1_cidr_block {
  type        = string
  default     = "10.0.0.0/16"
  description = "vpc default CIDR block"
}

variable vpc_2_cidr_block {
  type        = string
  default     = "10.2.0.0/16"
  description = "vpc default CIDR block"
}

variable vpc_cidr_public_block {
  type        = string
  default     = "10.0.1.0/24"
  description = "public CIDR block"
}

variable vpc_cidr_private_block {
  type        = string
  default     = "10.0.2.0/24"
  description = "private CIDR block"
}

resource "aws_vpc" "vpc1" {
  cidr_block = var.vpc_1_cidr_block
  tags = {
    Name = "tf-test-vpc-2"
    Project = "CIS Certification"
  }
}

resource "aws_subnet" "public" {
  vpc_id            = aws_vpc.vpc1.id
  cidr_block        = var.vpc_cidr_public_block
  availability_zone = "us-east-1a"


  tags = {
    Name    = "public-subnet-1"
    Project = "CIS Certification"
  }
}

resource "aws_subnet" "private" {
  vpc_id            = aws_vpc.vpc1.id
  cidr_block        = var.vpc_cidr_private_block
  availability_zone = "us-east-1a"

  tags = {
    Name    = "private-subnet-1"
    Project = "CIS Certification"
  }
}

resource "aws_vpc" "vpc2" {
  cidr_block = var.vpc_2_cidr_block
  tags = {
    Name = "tf-test-vpc-2"
    Project = "CIS Certification"
  }
}

resource "aws_internet_gateway" "igw" {
  vpc_id                  = aws_vpc.vpc1.id

  tags                    = {
    Name                  = "igw"
    Project               = "CIS Certification"
  }
}

resource "aws_eip" "nat" {}

resource "aws_nat_gateway" "nat" {
  allocation_id          = aws_eip.nat.id
  subnet_id              = aws_subnet.public.*.id[0]

  tags                   = {
    Name                 = "nat"
    Project              = "CIS Certification"
  }

  depends_on             = [aws_internet_gateway.igw]
}

data "aws_caller_identity" "current" {}

resource "aws_vpc_peering_connection" "my_peering" {
  peer_owner_id = data.aws_caller_identity.current.account_id
  peer_vpc_id   = aws_vpc.vpc1.id
  vpc_id        = aws_vpc.vpc2.id
  auto_accept   = true

  tags = {
    Name = "VPC Peering between vpc1 and vpc2"
    Project = "CIS Certification"
  }
}


resource "aws_route_table" "public_route_table2" {
  vpc_id = aws_vpc.vpc1.id

  tags = {
    Name = "public-route-table"
    Project = "CIS Certification"
  }
}

resource "aws_route_table" "private_route_table" {
  vpc_id = aws_vpc.vpc1.id

  tags = {
    Project = "CIS Certification"
  }
}

resource "aws_route" "private_route2" {
  route_table_id            = aws_route_table.public_route_table2.id
  destination_cidr_block    = "10.0.0.0/8"
  vpc_peering_connection_id = aws_vpc_peering_connection.my_peering.id
  depends_on                = [aws_route_table.public_route_table2]
}

resource "aws_route_table_association" "private_route_table_association" {
  subnet_id      = aws_subnet.private.*.id[0]
  route_table_id = aws_route_table.private_route_table.id
}

Negative test num. 3 - tf file

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 3.55.0"
    }
  }
}

provider "aws" {
  region = "us-east-1"
}

variable vpc_1_cidr_block {
  type        = string
  default     = "10.0.0.0/16"
  description = "vpc default CIDR block"
}

variable vpc_2_cidr_block {
  type        = string
  default     = "10.2.0.0/16"
  description = "vpc default CIDR block"
}

variable vpc_cidr_public_block {
  type        = string
  default     = "10.0.1.0/24"
  description = "public CIDR block"
}

variable vpc_cidr_private_block {
  type        = string
  default     = "10.0.2.0/24"
  description = "private CIDR block"
}

resource "aws_vpc" "vpc1" {
  cidr_block = var.vpc_1_cidr_block

  tags = {
    Name = "tf-test-vpc-1"
    Project = "CIS Certification"
  }
}

resource "aws_subnet" "public" {
  vpc_id            = aws_vpc.vpc1.id
  cidr_block        = var.vpc_cidr_public_block
  availability_zone = "us-east-1a"

  tags = {
    Name    = "public-subnet-1"
    Project = "CIS Certification"
  }
}

resource "aws_subnet" "private" {
  vpc_id            = aws_vpc.vpc1.id
  cidr_block        = var.vpc_cidr_private_block
  availability_zone = "us-east-1a"

  tags = {
    Name    = "private-subnet-1"
    Project = "CIS Certification"
  }
}

resource "aws_vpc" "vpc2" {
  cidr_block = var.vpc_2_cidr_block

  tags = {
    Name = "tf-test-vpc-2"
    Project = "CIS Certification"
  }
}

resource "aws_internet_gateway" "igw" {
  vpc_id                  = aws_vpc.vpc1.id

  tags                    = {
    Name                  = "igw"
    Project               = "CIS Certification"
  }
}

resource "aws_eip" "nat" {}

resource "aws_nat_gateway" "nat" {
  allocation_id          = aws_eip.nat.id
  subnet_id              = aws_subnet.public.*.id[0]

  tags                   = {
    Name                 = "nat"
    Project              = "CIS Certification"
  }

  depends_on             = [aws_internet_gateway.igw]
}

data "aws_caller_identity" "current" {}

resource "aws_vpc_peering_connection" "my_peering" {
  peer_owner_id = data.aws_caller_identity.current.account_id
  peer_vpc_id   = aws_vpc.vpc1.id
  vpc_id        = aws_vpc.vpc2.id
  auto_accept   = true

  tags = {
    Name = "VPC Peering between vpc1 and vpc2"
    Project = "CIS Certification"
  }
}

resource "aws_route_table" "public_route_table" {
  vpc_id = aws_vpc.vpc1.id

  route = [

    {
      cidr_block                 = "10.0.0.0/8"
      vpc_peering_connection_id  = aws_vpc_peering_connection.my_peering.id
      gateway_id                 = ""
      instance_id                = ""
      ipv6_cidr_block            = ""
      egress_only_gateway_id     = ""
      nat_gateway_id             = ""
      network_interface_id       = ""
      transit_gateway_id         = ""
      carrier_gateway_id         = ""
      destination_prefix_list_id = ""
      local_gateway_id           = ""
      vpc_endpoint_id            = ""

    }
  ]


  tags = {
    Name = "public_route_table"
    Project = "CIS Certification"
  }
}

resource "aws_route_table" "private_route_table" {
  vpc_id = aws_vpc.vpc1.id

  route {
    cidr_block                  = aws_vpc.vpc2.cidr_block
    vpc_peering_connection_id   = aws_vpc_peering_connection.my_peering.id
  }

  tags = {
    Name = "private_route_table"
    Project = "CIS Certification"
  }
}

resource "aws_route_table_association" "private_route_table_association" {
  subnet_id      = aws_subnet.private.id
  route_table_id = aws_route_table.private_route_table.id
}