Collect Passive DNS logs

Supported in:

Google secops SIEM

This document explains how to ingest Passive DNS logs to Google Security Operations using Google Cloud Storage V2.

Passive DNS is a DNS intelligence data source that captures historical DNS resolution records for threat analysis and domain investigation. Because the data is typically collected and stored as files, you must upload those files to a Google Cloud Storage (GCS) bucket, and then configure a Google SecOps feed to ingest them.

Before you begin

Make sure you have the following prerequisites:

• A Google SecOps instance.
• A Google Cloud project with Cloud Storage API enabled.
• Permissions to create and manage GCS buckets.
• Permissions to manage IAM policies on GCS buckets.
• Access to Passive DNS data files (for example, DNSDB, Farsight, or another Passive DNS provider).
• Passive DNS data exported in a supported format (for example, JSON or CSV).

Create a Google Cloud Storage bucket

1. Go to the Google Cloud Console.
2. Select your project or create a new one.
3. In the navigation menu, go to Cloud Storage > Buckets.
4. Click Create bucket.

5. Provide the following configuration details:

   Setting	Value
   Name your bucket	Enter a globally unique name (for example, passive-dns-logs)
   Location type	Choose based on your needs (Region, Dual-region, Multi-region)
   Location	Select the location closest to your Google SecOps instance (for example, us-central1)
   Storage class	Standard (recommended for frequently accessed logs)
   Access control	Uniform (recommended)
   Protection tools	Optional: Enable object versioning or retention policy

6. Click Create.

   Note: Record the bucket name. You will use it when configuring the Google SecOps feed.

Configure automated export of Passive DNS data to GCS

Passive DNS data is typically available as exported files from a DNS intelligence provider (for example, Farsight DNSDB, DomainTools, or Cisco Umbrella Investigate). To keep the data in GCS current, configure an automated export pipeline using one of the following approaches.

Option 1: Cloud Scheduler with Cloud Build (recommended)

Use Cloud Build triggered by Cloud Scheduler to run a containerized job that fetches Passive DNS data from your provider and writes it to GCS.

1. Create a service account for the export job:

   1. In the GCP Console, go to IAM & Admin > Service Accounts.
   2. Click Create Service Account.
   3. Provide the following configuration details:
      • Service account name: Enter passive-dns-export-sa
      • Service account description: Enter Service account for automated Passive DNS data export to GCS
   4. Click Create and Continue.
   5. Add the following roles:
      • Storage Object Admin (to write files to GCS)
      • Cloud Build Editor (to run Cloud Build jobs)
   6. Click Done.

2. Create a Cloud Build configuration file (cloudbuild.yaml):

   steps:
     - name: 'gcr.io/cloud-builders/gcloud'
       entrypoint: 'bash'
       args:
         - '-c'
         - |
           apt-get update && apt-get install -y curl jq
           # Fetch Passive DNS data from your provider
           # Replace with the actual API call for your provider
           # Example for Farsight DNSDB:
           TIMESTAMP=$(date -u +%Y%m%d_%H%M%S)
           curl -s -H "X-API-Key: $${PDNS_API_KEY}" \
             "https://api.dnsdb.info/dnsdb/v2/lookup/rrset/name/*.example.com" \
             -o /workspace/passive_dns_$${TIMESTAMP}.json
           # Upload to GCS
           gcloud storage cp /workspace/passive_dns_$${TIMESTAMP}.json \
             gs://${_BUCKET_NAME}/passive-dns/
   substitutions:
     _BUCKET_NAME: 'passive-dns-logs'
   

   Note: Replace the curl command with the actual API call for your Passive DNS provider. Consult your provider documentation for the correct endpoint, authentication method, and query parameters.

3. Store the API key as a Secret Manager secret:

   1. In the GCP Console, go to Security > Secret Manager.
   2. Click Create Secret.
   3. Enter pdns-api-key as the secret name.
   4. Enter your Passive DNS provider API key as the secret value.
   5. Click Create.

4. Create a Cloud Scheduler job to trigger the build:

   1. In the GCP Console, go to Cloud Scheduler.
   2. Click Create Job.

   3. Provide the following configuration details:

      Setting	Value
      Name	passive-dns-export-daily
      Region	Select the same region as your GCS bucket
      Frequency	0 3 * * * (daily at 3:00 AM UTC)
      Timezone	UTC (recommended)
      Target type	HTTP
      URL	https://cloudbuild.googleapis.com/v1/projects/YOUR_PROJECT_ID/builds
      HTTP method	POST
      Auth header	Add OAuth token
      Service account	passive-dns-export-sa@YOUR_PROJECT_ID.iam.gserviceaccount.com

   4. Click Create.

Option 2: Storage Transfer Service (for on-premise data stores)

If Passive DNS data is stored on an on-premise file system, use Storage Transfer Service with a Transfer Agent.

1. In the GCP Console, go to Storage Transfer Service.
2. Click Create transfer job.
3. Select POSIX filesystem as the source.
4. Follow the instructions to install the Storage Transfer Agent on a machine with access to the Passive DNS data files.

5. Configure the transfer job:

   Setting	Value
   Source directory	Path to the directory containing Passive DNS data files
   Destination bucket	passive-dns-logs
   Destination path	passive-dns/
   Schedule	Set a recurring schedule (for example, daily)

6. Click Create.

Retrieve the Google SecOps service account

1. Go to SIEM Settings > Feeds.
2. Click Add New Feed.
3. Click Configure a single feed.
4. In the Feed name field, enter a name for the feed (for example, Passive DNS Logs).
5. Select Google Cloud Storage V2 as the Source type.
6. Select Passive DNS as the Log type.
7. Click Get Service Account.

8. A unique service account email will be displayed, for example:

   [e-mail]
   

9. Copy this email address for use in the next step.

   Note: Each Google SecOps instance has a unique service account. Do not use service accounts from other documentation or examples.

Grant IAM permissions to the Google SecOps service account

The Google SecOps service account needs Storage Object Viewer role on your GCS bucket.

1. Go to Cloud Storage > Buckets.
2. Click on your bucket name (for example, passive-dns-logs).
3. Go to the Permissions tab.
4. Click Grant access.
5. Provide the following configuration details:
   • Add principals: Paste the Google SecOps service account email (for example, [e-mail]).
   • Assign roles: Select Storage Object Viewer.

6. Click Save.

   Note: If you plan to use the deletion option "Delete transferred files" or "Delete transferred files and empty directories," grant Storage Object Admin role instead of Storage Object Viewer.

Configure the Google SecOps feed

1. Go to SIEM Settings > Feeds.
2. Click Add New Feed.
3. Click Configure a single feed.
4. In the Feed name field, enter a name for the feed (for example, Passive DNS Logs).
5. Select Google Cloud Storage V2 as the Source type.
6. Select Passive DNS as the Log type.
7. Click Next.

8. Specify values for the following input parameters:

   • Storage bucket URL: Enter the GCS bucket URI:

     gs://passive-dns-logs/passive-dns/
     

     • Replace passive-dns-logs with your GCS bucket name.
     • Replace passive-dns with your configured prefix path.
   Note: Always include the trailing slash (/) at the end of the URI.

   • Source deletion option: Select the deletion option according to your preference:

     • Never: Never deletes any files after transfers (recommended for testing).
     • Delete transferred files: Deletes files after successful transfer.

     • Delete transferred files and empty directories: Deletes files and empty directories after successful transfer.

       Note: If you select a deletion option, the Google SecOps service account must have Storage Object Admin role instead of Storage Object Viewer. Update IAM permissions accordingly.

   • Maximum File Age: Include files modified in the last number of days (default is 180 days).

   • Asset namespace: The asset namespace.

   • Ingestion labels: The label to be 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
hostname	intermediary.hostname	Value copied directly
timestamp_s	metadata.event_timestamp	Parsed as UNIX timestamp
	metadata.event_type	Set to "NETWORK_DNS"
	network.application_protocol	Set to "DNS"
answer	network.dns.answers.data	Value from answer after removing trailing dot
ttl	network.dns.answers.ttl	Converted to integer
class	network.dns.questions.class	Mapped to numeric value (1 for IN, 3 for CH, 4 for HS)
query	network.dns.questions.name	Value from query after removing trailing dot
type	network.dns.questions.type	Mapped from type (uppercased) to numeric value using DNS type mapping
client	principal.ip	Value copied directly
server	target.ip	Value copied directly
	metadata.product_name	Set to "Passive DNS"

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