Ensure GCP Firewall rule does not allow all traffic on MySQL port 3306

Error: GCP Firewall rule allows all traffic on MySQL port 3306
Bridgecrew Policy ID:
Checkov Check ID: CKV_GCP_88
Severity: HIGH

GCP Firewall rule allows all traffic on MySQL port 3306

Description

Firewall rules setup fine grained allow/deny traffic policies to and from a virtual machine (VM). Enabled rules are always enforced and help protect instances from unwanted traffic. Firewall rules are defined at the network level, and only apply to the network where they are created.

While firewall rules are defined at the network level, connections are allowed or denied on a per-instance basis. Additionally, it is possible to create firewall rules that allow ingress traffic from any source on the internet. This firewall rule may be useful for troubleshooting but can inadvertently allow malicious or unwanted access to your instances. One such insecure firewall rule is for MySQL databases running on port TCP 3306.

We recommend you restrict or remove the the 0.0.0.0/0 MySQL firewall rule when you no longer need it.

Fix - Runtime

GCP Console

To remove your 0.0.0.0/0 MySQL firewall rule:

  1. Log in to the GCP Console at https://console.cloud.google.com.
  2. Navigate to Firewall.
  3. In the Firewall rules in this project section, use the Filter option and search for Filter:0.0.0.0/0. This filter returns all public firewall rules.
  4. Select your public MySQL (TCP port 3306) firewall rule and then select DELETE.

CLI Command

To delete your public MySQL firewall rule execute the following command:

gcloud compute firewall-rules delete FIREWALL-NAME

Replace FIREWALL-NAME with your target MySQL firewall rule name.

Fix - Buildtime

Terraform

  • Resource: google_compute_firewall
  • Field: source_ranges
resource "google_compute_firewall" "mysql-example" {
  name    = "mysql-example"
  network = google_compute_network.default.name
  allow {
    protocol = "tcp"
    ports    = ["3306"]
  }
-  source_ranges = ["0.0.0.0/0"]
}

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