Control: 2.7 Ensure That the Log Metric Filter and Alerts Exist for VPC Network Firewall Rule Changes

Description

It is recommended that a metric filter and alarm be established for Virtual Private Cloud(VPC) Network Firewall rule changes.

Monitoring for create or update firewall rule events gives insight to network access changes and may reduce the time it takes to detect suspicious activity.

Remediation

From Console

Create the prescribed log metric:

Go to Logging/Logs-based Metrics by visiting https://console.cloud.google.com/logs/metrics and click "CREATE METRIC".
Click the down arrow symbol on the Filter Bar at the rightmost corner and select Convert to Advanced Filter.
Clear any text and add:

resource.type="gce_firewall_rule"
AND (protoPayload.methodName:"compute.firewalls.patch"
OR protoPayload.methodName:"compute.firewalls.insert"
OR protoPayload.methodName:"compute.firewalls.delete")

Click Submit Filter. Display logs appear based on the filter text entered by the user.
In the Metric Editor menu on the right, fill out the name field. Set Units to 1 (default) and Type to Counter. This ensures that the log metric counts the number of log entries matching the advanced logs query.
Click Create Metric.

Create the prescribed Alert Policy:

Identify the newly created metric under the section User-defined Metrics at https://console.cloud.google.com/logs/metrics.
Click the 3-dot icon in the rightmost column for the new metric and select Create alert from Metric. A new page displays.
Fill out the alert policy configuration and click Save. Choose the alerting threshold and configuration that makes sense for the user's 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 `Aggregator` to `Count`
Set `Configuration`:
- Condition: above
- Threshold: 0
- For: most recent value

Configure the desired notifications channels in the section Notifications.
Name the policy and click Save.

From Command Line

Create the prescribed Log Metric:

Use the command: gcloud logging metrics create

Create the prescribed Alert Policy:

Use the command: gcloud alpha monitoring policies create

Usage

Run the control in your terminal:

powerpipe control run gcp_compliance.control.cis_v300_2_7

Snapshot and share results via Turbot Pipes:

powerpipe login
powerpipe control run gcp_compliance.control.cis_v300_2_7 --share

SQL

This control uses a named query:

with filter_data as (
  select
    m.project as project,
    display_name alert_name,
    count(m.name) metric_name
  from
    gcp_monitoring_alert_policy,
    jsonb_array_elements(conditions) as filter_condition
    join gcp_logging_metric m on m.filter ~ '\s*resource\.type\s*=\s*"gce_firewall_rule"\s*AND\s*\(\s*protoPayload\.methodName\s*:\s*"compute\.firewalls\.patch"\s*OR\s*protoPayload\.methodName\s*:\s*"compute\.firewalls\.insert"\s*OR\s*protoPayload\.methodName\s*:\s*"compute\.firewalls\.delete"\s*\)'
    and filter_condition -> 'conditionThreshold' ->> 'filter' like '%metric.type="' || m.metric_descriptor_type || '"%'
  where
    enabled
  group by
    m.project, display_name, m.name
)
select
  'https://cloudresourcemanager.googleapis.com/v1/projects/' || project_id resource,
  case
    when d.metric_name > 0 then 'ok'
    else 'alarm'
  end as status,
  case
    when d.metric_name > 0
      then 'Log metric and alert exist for network firewall rule changes.'
    else 'Log metric and alert do not exist network for firewall rule changes.'
  end as reason
  
  , project_id as project
from
  gcp_project as p
  left join filter_data as d on d.project = p.name;