Collect Cloud VPC Flow Logs

Supported in:

Google SecOps SIEM

Note: This feature is covered by Pre-GA Offerings Terms of the Google Security Operations Service Specific Terms. Pre-GA features might have limited support, and changes to pre-GA features might not be compatible with other pre-GA versions. For more information, see the Google Security Operations Technical Support Service guidelines and the Google Security Operations Service Specific Terms.

This document explains how to export Cloud VPC Flow Logs to Google Security Operations using Google Cloud. The parser transforms the logs from their built-in JSON format into the Google Security Operations UDM. It extracts relevant fields like source and destination IP, port, protocol, and bytes sent, then maps them to corresponding UDM fields, taking into account network direction and special cases for accurate representation in Google SecOps.

Before You Begin

• Ensure that you have a Google SecOps instance.
• Ensure that VPC Flow is set up and active in your Google Cloud environment.
• Ensure that you have privileged access to Google Cloud.

Create a Google Cloud Storage Bucket

1. Sign in to the Google Cloud console.

2. Go to the Cloud Storage Buckets page.

   Go to Buckets

3. Click Create.

4. On the Create a bucket page, enter your bucket information. After each of the following steps, click Continue to proceed to the next step:

   1. In the Get started section, do the following:

      1. Enter a unique name that meets the bucket name requirements; for example, vpcflow-logs.

      2. To enable hierarchical namespace, click the expander arrow to expand the Optimize for file oriented and data-intensive workloads section, and then select Enable Hierarchical namespace on this bucket.

         Note: You cannot enable hierarchical namespace in an existing bucket.

      3. To add a bucket label, click the expander arrow to expand the Labels section.

      4. Click Add label, and specify a key and a value for your label.

   2. In the Choose where to store your data section, do the following:

      1. Select a Location type.

      2. Use the location type menu to select a Location where object data within your bucket will be permanently stored.

         Note: If you select the dual-region location type, you can also choose to enable turbo replication by using the relevant checkbox.

      3. To set up cross-bucket replication, expand the Set up cross-bucket replication section.

   3. In the Choose a storage class for your data section, either select a default storage class for the bucket, or select Autoclass for automatic storage class management of your bucket's data.

   4. In the Choose how to control access to objects section, select not to enforce public access prevention, and select an access control model for your bucket's objects.

      Note: If public access prevention is already enforced by your project's organization policy, the Prevent public access checkbox is locked.

   5. In the Choose how to protect object data section, do the following:

      1. Select any of the options under Data protection that you want to set for your bucket.
      2. To choose how your object data will be encrypted, click the expander arrow labeled Data encryption, and select a Data encryption method.

5. Click Create.

Note: Be sure to provide your Google SecOps Service Account with permissions to Read or Read & Write to the newly created bucket.

Configure Log Export in Google Cloud VPC Flow

1. Sign in to Google Cloud account using your privileged account.
2. On Welcome page, click VPC Networks.
3. Click Default and a subnet page should appear.
4. Select all logs.
5. Click Flow Logs > Configure.
6. Select Aggregation Interval; for example, 30 SEC.
7. Provide Sample Rate; for example, 50%.
8. Click Save
9. Search Logging in the search bar and click Enter.
10. In Log Explorer, filter the logs by choosing VPC_flows in the Log Name and click Apply.
11. Click More Actions.
12. Click Create Sink.
13. Provide the following configurations:
    1. Sink Details: enter a name and description.
    2. Click Next.
    3. Sink Destination: select Cloud Storage Bucket.
    4. Cloud Storage Bucket: select the bucket created earlier or create a new bucket.
    5. Click Next.
    6. Choose Logs to include in Sink: a default log is populated when you select an option in Cloud Storage Bucket.
    7. Click Next.
    8. Optional: Choose Logs to filter out of Sink: select the logs that you would like not to sink.
14. Click Create Sink.

Configure a feed in Google SecOps to ingest Google Cloud VPC Flow Logs

1. Go to SIEM Settings > Feeds.
2. Click Add new.
3. In the Feed name field, enter a name for the feed; for example, Google Cloud VPC Flow Logs.
4. Select Google Cloud Storage as the Source type.
5. Select GCP VPC Flow as the Log type.
6. Click Get Service Account as the Chronicle Service Account.
7. Click Next.

8. Specify values for the following input parameters:

   • Storage Bucket URI: Google Cloud storage bucket URL in gs://my-bucket/<value> format.
   • URI Is A: Select Directory which includes subdirectories.

   • Source deletion options: select deletion option according to your preference.

     Note: If you select the Delete transferred files or Delete transferred files and empty directories option, make sure that you granted appropriate permissions to the service account.

   • Asset namespace: the asset namespace.

   • Ingestion labels: the label applied to the events from this feed.

9. Click Next.

10. Review your new feed configuration in the Finalize screen, and then click Submit.

UDM Mapping Table

Log field	UDM mapping	Logic
connection.dest_ip	target.asset.ip target.ip	Direct mapping when network.direction is OUTBOUND. Mapped from principal.ip when network.direction is INBOUND.
connection.dest_port	target.port	Converted to integer if greater than -1.
connection.protocol	network.ip_protocol	Converted to string, then mapped to integer. Based on the integer value, mapped to IP protocol name (e.g., TCP, UDP, ICMP).
connection.src_ip	principal.ip	Direct mapping.
connection.src_port	principal.port	Converted to integer.
dest_instance.region	target.location.name	Direct mapping.
dest_instance.vm_name	target.asset.hostname	Direct mapping.
dest_location.city	target.location.city	Direct mapping.
dest_location.country	target.location.country_or_region	Direct mapping.
dest_location.region	target.location.state	Direct mapping.
dest_vpc.project_id	target.namespace	Used with dest_vpc.vpc_name to form the target.namespace.
dest_vpc.vpc_name	target.namespace	Used with dest_vpc.project_id to form the target.namespace.
insertId	metadata.product_log_id	Direct mapping.
jsonPayload.bytes_sent	network.sent_bytes	Renamed to network.sent_bytes and converted to uinteger.
jsonPayload.packets_sent	network.sent_packets	Converted to integer.
labels.tunnel_id	additional.fields	Merged into additional.fields with the key Tunnel Id and type string_value.
logName	security_result.category_details	Direct mapping.
resource.labels.project_id	target.resource.name	Used to construct the target.resource.name with the format //cloudresourcemanager.googleapis.com/projects/{resource.labels.project_id}.
resource.labels.region	target.location.country_or_region	Direct mapping.
resource.labels.subnetwork_id	target.user.attribute.labels	Merged into target.user.attribute.labels with the key subnetwork_id.
resource.type	metadata.product_event_type	Direct mapping.
severity	security_result.severity	Mapped to LOW if the value is DEBUG.
src_gke_details.cluster.cluster_location	principal.resource.attribute.labels	Merged into principal.resource.attribute.labels with the key cluster_location.
src_gke_details.cluster.cluster_name	principal.resource.attribute.labels	Merged into principal.resource.attribute.labels with the key cluster_name.
src_gke_details.pod.pod_name	principal.resource.attribute.labels	Merged into principal.resource.attribute.labels with the key pod_name.
src_gke_details.pod.pod_namespace	principal.resource.attribute.labels	Merged into principal.resource.attribute.labels with the key pod_namespace.
src_instance.region	principal.location.name	Direct mapping.
src_instance.vm_name	principal.asset.hostname	Direct mapping.
src_location.city	principal.location.city	Direct mapping.
src_location.country	principal.location.country_or_region	Direct mapping.
src_location.region	principal.location.state	Direct mapping.
src_vpc.project_id	principal.namespace	Used with src_vpc.vpc_name to form the principal.namespace.
src_vpc.vpc_name	principal.namespace	Used with src_vpc.project_id to form the principal.namespace.
textPayload	additional.fields	Merged into additional.fields with the key Textpayload and type string_value.
timestamp	metadata.event_timestamp	Used to populate event_timestamp if jsonPayload.end_time is empty.
	metadata.description	A description of the network flow, including the reporter (SRC or DEST) and the direction (INBOUND or OUTBOUND), is generated based on the 'reporter' field.
	metadata.event_type	Set to NETWORK_CONNECTION for VPC flow logs and USER_RESOURCE_ACCESS for other log types.
	metadata.log_type	Set to GCP_VPC_FLOW.
	metadata.product_name	Set to GCP VPC Flow Logs.
	metadata.product_version	Set to 1.0.
	metadata.vendor_name	Set to Google Cloud.
	network.direction	Determined based on the target.port. If the port is a well-known or reserved port, it's considered INBOUND; otherwise, it's considered OUTBOUND.
	security_result.severity	Set to LOW by default.
	target.resource.attribute.cloud.environment	Set to GOOGLE_CLOUD_PLATFORM.
	target.resource.resource_type	Set to CLOUD_PROJECT.

Changes

2024-10-24

Enhancement:

• Interchanged mapping of principal.ip, principal.port with target.ip and target.port respectively.

2024-03-15

Enhancement:

• Mapped jsonPayload.src_gke_details.pod.pod_namespace, jsonPayload.src_gke_details.pod.pod_name, jsonPayload.src_gke_details.cluster.cluster_name, jsonPayload.src_gke_details.cluster.cluster_location to principal.resource.attribute.labels.
• Mapped jsonPayload.dest_gke_details.pod.pod_namespace, jsonPayload.dest_gke_details.pod.pod_name, jsonPayload.dest_gke_details.cluster.cluster_name, jsonPayload.dest_gke_details.cluster.cluster_location to target.resource.attribute.labels.

2023-05-23

Enhancement:

• Mapped 'metadata.event_type' to 'USER_RESOURCE_ACCESS' when field 'logName' does not contain 'vpc_flows'.
• Mapped 'timestamp' to 'events.timestamp'.
• Mapped 'textPayload', 'labels.tunnel_id' to 'additional.fields'.
• Mapped 'resource.labels.region' to 'target.location.country_or_region'.
• Added null checks for various fields wherever required.

2023-04-10

Enhancement:

• Set target.resource.attribute.cloud.environment to GOOGLE_CLOUD_PLATFORM.
• Set target.resource.name to the full resource name value.

2022-07-22

Enhancement:

• Mapped resource.labels.location to principal.location.name.
• Mapped resource.labels.subnetwork_id to target.user.attribute.labels.
• Mapped logName to security_result.category_details.

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