Logging metric filter and alert for network route changes should be configured

Description

Routes define the paths network traffic takes from a VM instance to another destination, which can be inside the same VPC network or outside of it. Monitoring changes to route tables helps prevent accidental or malicious changes that could result in either dropped packets or network hijacking.

Remediation Steps

Google Cloud Console

This is a two-part process. First, you create the log metric. Next, you create an alert policy.

Step 1: To create the log metric:

  • Navigate to Logs-based Metrics and click CREATE METRIC.

  • Ensure Metric Type is set to Counter.

  • Under Details, enter a name and description, and set Units to 1.

  • Under Filter selection, clear any text in the Build filter box and enter the following:

resource.type="gce_route"
AND (protoPayload.methodName:compute.routes.delete
OR protoPayload.methodName:compute.routes.insert)
  • Click Create Metric.

Step 2: To create the alert policy:

  • Navigate to Logs-based Metrics and identify the newly created metric under the section User-defined Metrics.

  • Click the 3-dot icon in the rightmost column for the new metric and select Create alert from Metric.

  • In the Find resource type and metric section, remove the selected resource type and select Global as the resource type instead.

  • Set Aggregator to Count and set the desired time period.

  • Under Configuration, choose the alerting threshold and configuration that makes sense for your organization. For example, a threshold of zero (0) for the most recent value ensures that a notification is triggered for every owner change in the project:

Set `Configuration`:
- Condition: above
- Threshold: 0
- For: most recent value
  • Click Save.

  • Configure the desired notifications channels in the section Notifications.

  • Name the policy and click Save.

gcloud CLI

  • To create the log metric:

    • gcloud beta logging metrics create

For flags, see Google Cloud’s CLI reference.

  • To create the alert policy:

    • gcloud alpha monitoring policies create

For flags, see Google Cloud’s CLI reference.