Serial Ports Are Enabled For VM Instances

• Query id: 97fa667a-d05b-4f16-9071-58b939f34751
• Query name: Serial Ports Are Enabled For VM Instances
• Platform: Terraform
• Severity: Medium
• Category: Networking and Firewall
• URL: Github

Description

Google Compute Engine VM instances should not enable serial ports. When enabled, anyone can access your VM, if they know the username, project ID, SSH key, instance name and zone
Documentation

Code samples

Code samples with security vulnerabilities

Postitive test num. 1 - tf file

resource "google_compute_instance" "positive1" {
  name         = "test"
  machine_type = "e2-medium"
  zone         = "us-central1-a"

  tags = ["foo", "bar"]

  boot_disk {
    initialize_params {
      image = "debian-cloud/debian-9"
    }
  }

  scratch_disk {
    interface = "SCSI"
  }

  network_interface {
    network = "default"

    access_config {
    }
  }

  metadata = {
    serial-port-enable = true
  }

  metadata_startup_script = "echo hi > /test.txt"

  service_account {
    scopes = ["userinfo-email", "compute-ro", "storage-ro"]
  }
}

resource "google_compute_project_metadata" "positive2" {
  metadata = {
    serial-port-enable = "TRUE"
  }
}

resource "google_compute_project_metadata_item" "positive3" {
  key   = "serial-port-enable"
  value = "TRUE"
}

Code samples without security vulnerabilities

Negative test num. 1 - tf file

resource "google_compute_instance" "negative1" {
  name         = "test"
  machine_type = "e2-medium"
  zone         = "us-central1-a"

  tags = ["foo", "bar"]

  boot_disk {
    initialize_params {
      image = "debian-cloud/debian-9"
    }
  }

  scratch_disk {
    interface = "SCSI"
  }

  network_interface {
    network = "default"

    access_config {
    }
  }

  metadata = {
    serial-port-enable = "FALSE"
  }

  metadata_startup_script = "echo hi > /test.txt"

  service_account {
    scopes = ["userinfo-email", "compute-ro", "storage-ro"]
  }
}

resource "google_compute_project_metadata" "negative2" {
  metadata = {
    serial-port-enable = false
  }
}

resource "google_compute_project_metadata_item" "negative3" {
  key   = "my_metadata"
  value = "my_value"
}