Google Compute network using firewall rule that allows port range

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Metadata

Id: e6f61c37-106b-449f-a5bb-81bfcaceb8b4

Cloud Provider: GCP

Platform: Terraform

Severity: Low

Category: Networking and Firewall

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Description

Allowing a port range in a Google Compute Network firewall rule, such as ports = ["80", "8080", "1000-2000"], can expose unnecessary services and increase the attack surface of your cloud environment. Attackers may exploit any open ports within the specified range, leading to potential unauthorized access or compromise of resources. To reduce risk, firewall rules should restrict access to only required ports, as shown in the following configuration:

allow {
  protocol = "tcp"
  ports    = ["80", "8080"]
}

Compliant Code Examples

resource "google_compute_firewall" "negative1" {
  name    = "test-firewall"
  network = google_compute_network.negative1.name

  allow {
    protocol = "icmp"
  }

  allow {
    protocol = "tcp"
    ports    = ["80", "8080"]
  }

  source_tags = ["web"]
}

resource "google_compute_network" "negative1" {
  name = "test-network"
}

Non-Compliant Code Examples

resource "google_compute_firewall" "positive1" {
  name    = "test-firewall"
  network = google_compute_network.positive1.name

  allow {
    protocol = "icmp"
  }

  allow {
    protocol = "tcp"
    ports    = ["80", "8080", "1000-2000"]
  }

  source_tags = ["web"]
}

resource "google_compute_network" "positive1" {
  name = "test-network"
}