Collect Tenable Audit logs

Supported in:

Google secops SIEM

This document explains how to ingest Tenable Audit logs to Google Security Operations using Google Cloud Storage V2.

Tenable Audit is a cloud-based vulnerability management platform (cloud.tenable.com) that generates audit logs for user authentication, API access, configuration changes, and administrative actions. The Tenable.io REST API provides programmatic access to these audit event logs.

Before you begin

Make sure that you have the following prerequisites:

• A Google SecOps instance
• A GCP project with Cloud Storage API enabled
• Permissions to create and manage GCS buckets
• Permissions to manage IAM policies on GCS buckets
• Permissions to create Cloud Run services, Pub/Sub topics, and Cloud Scheduler jobs
• Privileged access to Tenable.io (cloud.tenable.com) with administrator permissions
• Tenable.io API keys (access key and secret key) with audit log read permissions

Create 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, tenable-audit-logs)
   Location type	Choose based on your needs (Region, Dual-region, Multi-region)
   Location	Select the location (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.

Collect Tenable.io API credentials

Generate API keys

1. Sign in to Tenable.io.
2. Click your user icon in the top-right corner and select My Account.
3. Go to the API Keys tab.
4. Click Generate to create a new API key pair.

5. Copy and save the following details in a secure location:

   • Access Key: The API access key
   • Secret Key: The API secret key
   Note: The secret key is displayed only once. If lost, you must generate a new key pair. Store both keys securely as environment variables.

Verify API access

• Test your credentials before proceeding with the integration:

  # Replace with your actual credentials
  ACCESS_KEY="your-access-key"
  SECRET_KEY="your-secret-key"
  
  curl -s -H "X-ApiKeys: accessKey=${ACCESS_KEY};secretKey=${SECRET_KEY}" \
      "https://cloud.tenable.com/audit-log/v1/events?limit=1" | head -c 500
  

Verify permissions

To verify the account has the required permissions:

1. Sign in to Tenable.io.
2. Go to Settings > Users.
3. Verify that your account has Administrator role or a custom role with Audit Log read permissions.
4. If you do not have the required permissions, contact your Tenable.io administrator.

Create service account for Cloud Run function

The Cloud Run function needs a service account with permissions to write to GCS bucket and be invoked by Pub/Sub.

Create service account

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 tenable-audit-collector-sa
   • Service account description: Enter Service account for Cloud Run function to collect Tenable Audit logs
4. Click Create and Continue.
5. In the Grant this service account access to project section, add the following roles:
   1. Click Select a role.
   2. Search for and select Storage Object Admin.
   3. Click + Add another role.
   4. Search for and select Cloud Run Invoker.
   5. Click + Add another role.
   6. Search for and select Cloud Functions Invoker.
6. Click Continue.
7. Click Done.

These roles are required for:

• Storage Object Admin: Write logs to GCS bucket and manage state files
• Cloud Run Invoker: Allow Pub/Sub to invoke the function
• Cloud Functions Invoker: Allow function invocation

Grant IAM permissions on GCS bucket

Grant the service account write permissions on the GCS bucket:

1. Go to Cloud Storage > Buckets.
2. Click on your bucket name (for example, tenable-audit-logs).
3. Go to the Permissions tab.
4. Click Grant access.
5. Provide the following configuration details:
   • Add principals: Enter the service account email (for example, tenable-audit-collector-sa@PROJECT_ID.iam.gserviceaccount.com)
   • Assign roles: Select Storage Object Admin
6. Click Save.

Create Pub/Sub topic

Create a Pub/Sub topic that Cloud Scheduler will publish to and the Cloud Run function will subscribe to.

1. In the GCP Console, go to Pub/Sub > Topics.
2. Click Create topic.
3. Provide the following configuration details:
   • Topic ID: Enter tenable-audit-trigger
   • Leave other settings as default
4. Click Create.

Create Cloud Run function to collect logs

The Cloud Run function will be triggered by Pub/Sub messages from Cloud Scheduler to fetch logs from the Tenable.io REST API and write them to GCS.

1. In the GCP Console, go to Cloud Run.
2. Click Create service.
3. Select Function (use an inline editor to create a function).

4. In the Configure section, provide the following configuration details:

   Setting	Value
   Service name	tenable-audit-collector
   Region	Select region matching your GCS bucket (for example, us-central1)
   Runtime	Select Python 3.12 or later

5. In the Trigger (optional) section:

   1. Click + Add trigger.
   2. Select Cloud Pub/Sub.
   3. In Select a Cloud Pub/Sub topic, choose the topic tenable-audit-trigger.
   4. Click Save.

6. In the Authentication section:

   1. Select Require authentication.
   2. Check Identity and Access Management (IAM).
   Note: Pub/Sub will automatically handle authentication when invoking the function.

7. Scroll down and expand Containers, Networking, Security.

8. Go to the Security tab:

   • Service account: Select the service account tenable-audit-collector-sa.

9. Go to the Containers tab:

   1. Click Variables & Secrets.
   2. Click + Add variable for each environment variable:

   Variable Name	Example Value	Description
   GCS_BUCKET	tenable-audit-logs	GCS bucket name
   GCS_PREFIX	tenable	Prefix for log files
   STATE_KEY	tenable/state.json	State file path
   TENABLE_ACCESS_KEY	your-access-key	Tenable.io access key
   TENABLE_SECRET_KEY	your-secret-key	Tenable.io secret key
   MAX_RECORDS	5000	Max records per run
   PAGE_SIZE	1000	Records per page
   LOOKBACK_HOURS	24	Initial lookback period

10. In the Variables & Secrets section, scroll down to Requests:

    • Request timeout: Enter 600 seconds (10 minutes)

11. Go to the Settings tab:

    • In the Resources section:
      • Memory: Select 512 MiB or higher
      • CPU: Select 1

12. In the Revision scaling section:

    • Minimum number of instances: Enter 0
    • Maximum number of instances: Enter 100 (or adjust based on expected load)

13. Click Create.

14. Wait for the service to be created (1-2 minutes).

15. After the service is created, the inline code editor will open automatically.

Add function code

1. Enter main in the Entry point field.

2. In the inline code editor, create two files:

   • main.py:

   import functions_framework
   from google.cloud import storage
   import json
   import os
   import urllib3
   from datetime import datetime, timezone, timedelta
   import time
   
   # Initialize HTTP client with timeouts
   http = urllib3.PoolManager(
     timeout=urllib3.Timeout(connect=5.0, read=30.0),
     retries=False,
   )
   
   # Initialize Storage client
   storage_client = storage.Client()
   
   # Environment variables
   GCS_BUCKET = os.environ.get('GCS_BUCKET')
   GCS_PREFIX = os.environ.get('GCS_PREFIX', 'tenable')
   STATE_KEY = os.environ.get('STATE_KEY', 'tenable/state.json')
   TENABLE_ACCESS_KEY = os.environ.get('TENABLE_ACCESS_KEY')
   TENABLE_SECRET_KEY = os.environ.get('TENABLE_SECRET_KEY')
   MAX_RECORDS = int(os.environ.get('MAX_RECORDS', '5000'))
   PAGE_SIZE = int(os.environ.get('PAGE_SIZE', '1000'))
   LOOKBACK_HOURS = int(os.environ.get('LOOKBACK_HOURS', '24'))
   
   TENABLE_API_BASE = 'https://cloud.tenable.com'
   
   def to_unix_millis(dt: datetime) -> int:
     """Convert datetime to Unix epoch milliseconds."""
     if dt.tzinfo is None:
       dt = dt.replace(tzinfo=timezone.utc)
     dt = dt.astimezone(timezone.utc)
     return int(dt.timestamp() * 1000)
   
   def parse_datetime(value: str) -> datetime:
     """Parse ISO datetime string to datetime object."""
     if value.endswith("Z"):
       value = value[:-1] + "+00:00"
     return datetime.fromisoformat(value)
   
   @functions_framework.cloud_event
   def main(cloud_event):
     """
     Cloud Run function triggered by Pub/Sub to fetch Tenable.io
     audit logs and write to GCS.
   
     Args:
       cloud_event: CloudEvent object containing Pub/Sub message
     """
   
     if not all([GCS_BUCKET, TENABLE_ACCESS_KEY, TENABLE_SECRET_KEY]):
       print('Error: Missing required environment variables')
       return
   
     try:
       bucket = storage_client.bucket(GCS_BUCKET)
   
       # Load state
       state = load_state(bucket, STATE_KEY)
   
       # Determine time window
       now = datetime.now(timezone.utc)
       last_time = None
   
       if isinstance(state, dict) and state.get("last_event_time"):
         try:
           last_time = parse_datetime(state["last_event_time"])
           # Overlap by 2 minutes to catch any delayed events
           last_time = last_time - timedelta(minutes=2)
         except Exception as e:
           print(f"Warning: Could not parse last_event_time: {e}")
   
       if last_time is None:
         last_time = now - timedelta(hours=LOOKBACK_HOURS)
   
       print(f"Fetching logs from {last_time.isoformat()} to {now.isoformat()}")
   
       # Fetch logs
       records, newest_event_time = fetch_logs(
         start_time=last_time,
         end_time=now,
         page_size=PAGE_SIZE,
         max_records=MAX_RECORDS,
       )
   
       if not records:
         print("No new log records found.")
         save_state(bucket, STATE_KEY, now.isoformat())
         return
   
       # Write to GCS as NDJSON
       timestamp = now.strftime('%Y%m%d_%H%M%S')
       object_key = f"{GCS_PREFIX}/logs_{timestamp}.ndjson"
       blob = bucket.blob(object_key)
   
       ndjson = '\n'.join([json.dumps(record, ensure_ascii=False) for record in records]) + '\n'
       blob.upload_from_string(ndjson, content_type='application/x-ndjson')
   
       print(f"Wrote {len(records)} records to gs://{GCS_BUCKET}/{object_key}")
   
       # Update state with newest event time
       if newest_event_time:
         save_state(bucket, STATE_KEY, newest_event_time)
       else:
         save_state(bucket, STATE_KEY, now.isoformat())
   
       print(f"Successfully processed {len(records)} records")
   
     except Exception as e:
       print(f'Error processing logs: {str(e)}')
       raise
   
   def load_state(bucket, key):
     """Load state from GCS."""
     try:
       blob = bucket.blob(key)
       if blob.exists():
         state_data = blob.download_as_text()
         return json.loads(state_data)
     except Exception as e:
       print(f"Warning: Could not load state: {e}")
   
     return {}
   
   def save_state(bucket, key, last_event_time_iso: str):
     """Save the last event timestamp to GCS state file."""
     try:
       state = {'last_event_time': last_event_time_iso}
       blob = bucket.blob(key)
       blob.upload_from_string(
         json.dumps(state, indent=2),
         content_type='application/json'
       )
       print(f"Saved state: last_event_time={last_event_time_iso}")
     except Exception as e:
       print(f"Warning: Could not save state: {e}")
   
   def fetch_logs(start_time: datetime, end_time: datetime, page_size: int, max_records: int):
     """
     Fetch audit event logs from Tenable.io REST API
     with pagination and rate limiting.
   
     Args:
       start_time: Start time for log query
       end_time: End time for log query
       page_size: Number of records per page
       max_records: Maximum total records to fetch
   
     Returns:
       Tuple of (records list, newest_event_time ISO string)
     """
     endpoint = f"{TENABLE_API_BASE}/audit-log/v1/events"
   
     headers = {
       'X-ApiKeys': f'accessKey={TENABLE_ACCESS_KEY};secretKey={TENABLE_SECRET_KEY}',
       'Accept': 'application/json',
       'User-Agent': 'GoogleSecOps-TenableAuditCollector/1.0'
     }
   
     records = []
     newest_time = None
     page_num = 0
     backoff = 1.0
     next_token = None
   
     while True:
       page_num += 1
   
       if len(records) >= max_records:
         print(f"Reached max_records limit ({max_records})")
         break
   
       # Build query parameters
       params = {
         'f': f'date.gt:{start_time.strftime("%Y-%m-%dT%H:%M:%SZ")}',
         'limit': min(page_size, max_records - len(records))
       }
   
       if next_token:
         params['next'] = next_token
   
       query_string = '&'.join(f"{k}={v}" for k, v in params.items())
       url = f"{endpoint}?{query_string}"
   
       try:
         response = http.request(
           'GET',
           url,
           headers=headers
         )
   
         # Handle rate limiting with exponential backoff
         if response.status == 429:
           retry_after = int(response.headers.get('Retry-After', str(int(backoff))))
           print(f"Rate limited (429). Retrying after {retry_after}s...")
           time.sleep(retry_after)
           backoff = min(backoff * 2, 30.0)
           continue
   
         backoff = 1.0
   
         if response.status != 200:
           print(f"HTTP Error: {response.status}")
           response_text = response.data.decode('utf-8')
           print(f"Response body: {response_text}")
           return [], None
   
         data = json.loads(response.data.decode('utf-8'))
   
         page_results = data.get('events', data.get('data', []))
   
         if not page_results:
           print(f"No more results (empty page)")
           break
   
         print(f"Page {page_num}: Retrieved {len(page_results)} events")
         records.extend(page_results)
   
         # Track newest event time
         for event in page_results:
           try:
             event_ts = event.get('received') or event.get('timestamp')
             if event_ts:
               event_time = str(event_ts)
               if newest_time is None or parse_datetime(event_time) > parse_datetime(newest_time):
                 newest_time = event_time
           except Exception as e:
             print(f"Warning: Could not parse event time: {e}")
   
         # Check for pagination token
         pagination = data.get('pagination', {})
         next_token = pagination.get('next')
         if not next_token:
           print("No more pages (no next token)")
           break
   
       except Exception as e:
         print(f"Error fetching logs: {e}")
         return [], None
   
     print(f"Retrieved {len(records)} total records from {page_num} pages")
     return records, newest_time
   

   • requirements.txt:

   functions-framework==3.*
   google-cloud-storage==2.*
   urllib3>=2.0.0
   

3. Click Deploy to save and deploy the function.

4. Wait for deployment to complete (2-3 minutes).

   Note: The Pub/Sub trigger configuration automatically creates the necessary subscriptions and permissions.

Create Cloud Scheduler job

Cloud Scheduler will publish messages to the Pub/Sub topic at regular intervals, triggering the Cloud Run function.

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

3. Provide the following configuration details:

   Setting	Value
   Name	tenable-audit-collector-hourly
   Region	Select same region as Cloud Run function
   Frequency	0 * * * * (every hour, on the hour)
   Timezone	Select timezone (UTC recommended)
   Target type	Pub/Sub
   Topic	Select the topic tenable-audit-trigger
   Message body	{} (empty JSON object)

4. Click Create.

Schedule frequency options

Choose frequency based on log volume and latency requirements:

Frequency	Cron Expression	Use Case
Every 5 minutes	*/5 * * * *	High-volume, low-latency
Every 15 minutes	*/15 * * * *	Medium volume
Every hour	0 * * * *	Standard (recommended)
Every 6 hours	0 */6 * * *	Low volume, batch processing
Daily	0 0 * * *	Historical data collection

Test the integration

1. In the Cloud Scheduler console, find your job.
2. Click Force run to trigger the job manually.
3. Wait a few seconds.
4. Go to Cloud Run > Services.
5. Click on tenable-audit-collector.
6. Click the Logs tab.

7. Verify the function executed successfully. Look for:

   Fetching logs from YYYY-MM-DDTHH:MM:SS+00:00 to YYYY-MM-DDTHH:MM:SS+00:00
   Page 1: Retrieved X events
   Wrote X records to gs://tenable-audit-logs/tenable/logs_YYYYMMDD_HHMMSS.ndjson
   Successfully processed X records
   

8. Go to Cloud Storage > Buckets.

9. Click on your bucket name (tenable-audit-logs).

10. Navigate to the tenable/ folder.

11. Verify that a new .ndjson file was created with the current timestamp.

If you see errors in the logs:

• HTTP 401: Check API keys in environment variables
• HTTP 403: Verify account has required administrator permissions in Tenable.io
• HTTP 429: Rate limiting - function will automatically retry with backoff
• Missing environment variables: Check all required variables are set

Configure a feed in Google SecOps to ingest Tenable Audit logs

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, Tenable Audit Logs).
5. Select Google Cloud Storage V2 as the Source type.
6. Select Tenable Audit as the Log type.

7. Click Get Service Account. A unique service account email will be displayed, for example:

   [e-mail]
   

8. Copy this email address.

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

9. Click Next.

10. Specify values for the following input parameters:

    • Storage bucket URL: Enter the GCS bucket URI with the prefix path:

      gs://tenable-audit-logs/tenable/
      

      • Replace:
        • tenable-audit-logs: Your GCS bucket name.
        • tenable: Optional prefix/folder path where logs are stored (leave empty for root).
    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 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

11. Click Next.

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

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.
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
   • 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.

UDM mapping table

Log Field	UDM Mapping	Logic
crud, fields	additional.fields	For crud: set crud_label.key = "crud", crud_label.value.string_value = %{crud}, merge crud_label to additional.fields; For fields: if field.key != "X-Forwarded-For" and not (field.key == "X-Access-Type" and field.value == "apikey"), set fields_label.key = field.key, fields_label.value.string_value = field.value, merge fields_label to additional.fields
fields	event.idm.read_only_udm.extensions.auth.mechanism	For field in fields, if field.key == "X-Access-Type" and field.value == "apikey", set to "MECHANISM_OTHER"
fields	event.idm.read_only_udm.extensions.auth.type	Set to "MACHINE" if X-Access-Type == "apikey" in fields, else "AUTHTYPE_UNSPECIFIED"
description	metadata.description	Value copied directly if description != ""
received	metadata.event_timestamp	Converted using date match patterns ISO8601, yyyy-MM-ddTHH:mm:ss.SSZ
has_principal, has_target, has_target_user, metadata.product_event_type	metadata.event_type	Set to "USER_LOGIN" if has_principal true, has_target true, has_target_user true, product_event_type =~ "user.authenticate"; else "USER_CREATION" if has_principal true, has_target true, has_target_user true, product_event_type =~ "user.create"; else "USER_DELETION" if has_principal true, has_target true, has_target_user true, product_event_type =~ "users.delete"; else "USER_LOGOUT" if has_principal true, has_target true, has_target_user true, product_event_type =~ "user.logout"; else "STATUS_UPDATE" if has_principal true; else "USER_UNCATEGORIZED" if has_user true; else "GENERIC_EVENT"
action	metadata.product_event_type	Value copied directly if action != ""
id	metadata.product_log_id	Value copied directly if id != ""
fields	principal.asset.ip	For field in fields, if field.key == "X-Forwarded-For", parse field.value as JSON {"ips":[...]}, for each ip in ips, merge ip to principal.asset.ip
fields	principal.ip	For field in fields, if field.key == "X-Forwarded-For", parse field.value as JSON {"ips":[...]}, for each ip in ips, merge ip to principal.ip
actor.name	principal.user.email_addresses	Merged if actor.name =~ "^.+@.+$"
actor.id	principal.user.userid	Value copied directly if actor.id != ""
is_failure	security_result.category	Set to "AUTH_VIOLOATION" if is_failure == "true"
is_anonymous, is_failure	security_result.detection_fields	For is_anonymous: convert to string, set is_anonymous_label.key = "is_anonymous", value = %{is_anonymous}, merge if not empty; same for is_failure with key "is_failure"
target1.name	target.user.email_addresses	Merged if target1.name =~ "^.+@.+$"
target1.type	target.user.role_name	Value copied directly if target1.type != ""
target1.id	target.user.userid	Value copied directly if target1.id != ""
	metadata.product_name	Set to "TENABLE AUDIT"
	metadata.vendor_name	Set to "TENABLE"

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