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Event Information

  • The google.pubsub.v1.Subscriber.ModifyPushConfig event in GCP for Pubsub indicates that a modification has been made to the push configuration of a subscriber.
  • This event is triggered when changes are made to the endpoint URL or other parameters related to the push delivery mechanism for a Pubsub subscriber.
  • It is important to monitor and analyze this event to track any modifications made to the push configuration, ensuring the correct delivery of messages to the subscriber.

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Examples

  1. Unauthorized modification of push configuration: If security is impacted with google.pubsub.v1.Subscriber.ModifyPushConfig in GCP for Pubsub, it could potentially allow unauthorized individuals to modify the push configuration settings. This could lead to malicious actors redirecting messages to unauthorized endpoints or intercepting sensitive data.

  2. Exposure of sensitive information: If security is impacted with google.pubsub.v1.Subscriber.ModifyPushConfig in GCP for Pubsub, it may result in the exposure of sensitive information. Attackers could modify the push configuration to redirect messages to their own endpoints, allowing them to access and potentially exploit sensitive data contained within the messages.

  3. Disruption of message delivery: If security is impacted with google.pubsub.v1.Subscriber.ModifyPushConfig in GCP for Pubsub, it could lead to the disruption of message delivery. Unauthorized modifications to the push configuration could result in messages being sent to incorrect or non-existent endpoints, causing delays or failures in message delivery, which can impact critical business processes or workflows.

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Remediation

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Using Console

  1. Enable audit logging for GCP Pub/Sub:

    • Go to the GCP Console and navigate to the Pub/Sub section.
    • Select the specific Pub/Sub topic or subscription that you want to enable audit logging for.
    • Click on the “Edit” button to modify the settings.
    • Under the “Logging” section, enable the “Audit logs” option.
    • Choose the appropriate log sink destination, such as Cloud Storage or BigQuery.
    • Save the changes.

  2. Implement VPC Service Controls for GCP Pub/Sub:

    • Go to the GCP Console and navigate to the VPC Service Controls section.
    • Create a new service perimeter or select an existing one that includes the Pub/Sub resources.
    • Configure the access levels and permissions for the Pub/Sub resources within the service perimeter.
    • Apply the service perimeter to the appropriate projects or organizations.
    • Save the changes.

  3. Implement IAM roles and permissions for GCP Pub/Sub:

    • Go to the GCP Console and navigate to the IAM & Admin section.
    • Select the specific project that contains the Pub/Sub resources.
    • Click on the “IAM” tab to manage IAM roles and permissions.
    • Assign the appropriate IAM roles to the users or service accounts that need access to Pub/Sub.
    • Make sure to follow the principle of least privilege and only grant the necessary permissions.
    • Save the changes.

Note: These instructions assume that you have the necessary permissions and access to the GCP Console.

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Using CLI

To remediate the issues mentioned in the previous response for GCP Pub/Sub using GCP CLI, you can follow these steps:

  1. Enable audit logging for Pub/Sub:

    • Use the following command to enable audit logging for Pub/Sub: 
      gcloud pubsub topics set-iam-policy <TOPIC_NAME> policy.json
    • Replace <TOPIC_NAME> with the name of the Pub/Sub topic you want to enable audit logging for.
    • Create a policy.json file with the following content: 
      {
  "auditConfigs": [
    {
      "service": "pubsub.googleapis.com",
      "auditLogConfigs": [
        {
          "logType": "ADMIN_READ"
        },
        {
          "logType": "DATA_READ"
        },
        {
          "logType": "DATA_WRITE"
        }
      ]
    }
  ]
}

  2. Implement VPC Service Controls for Pub/Sub:

    • Use the following command to create a VPC Service Control perimeter: 
      gcloud access-context-manager perimeters create <PERIMETER_NAME> --resources=projects/<PROJECT_ID> --restricted-services=pubsub.googleapis.com
    • Replace <PERIMETER_NAME> with a name for the VPC Service Control perimeter.
    • Replace <PROJECT_ID> with your GCP project ID.

  3. Enable Pub/Sub encryption at rest:

    • Use the following command to enable encryption at rest for Pub/Sub: 
      gcloud pubsub topics update <TOPIC_NAME> --message-storage-policy-encryption-key=projects/<PROJECT_ID>/locations/global/keyRings/<KEY_RING_NAME>/cryptoKeys/<CRYPTO_KEY_NAME>
    • Replace <TOPIC_NAME> with the name of the Pub/Sub topic you want to enable encryption at rest for.
    • Replace <PROJECT_ID> with your GCP project ID.
    • Replace <KEY_RING_NAME> and <CRYPTO_KEY_NAME> with the name of the key ring and crypto key you want to use for encryption.

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Using Python

To remediate the issues mentioned in the previous response for GCP Pub/Sub using Python, you can follow these steps:

  1. Enable VPC Service Controls:

    • Use the google-cloud-securitycenter library to enable VPC Service Controls for your project.
    • Here’s an example Python script to enable VPC Service Controls:
    from google.cloud import securitycenter

client = securitycenter.SecurityCenterClient()

# Set the project ID and organization ID
project_id = 'your-project-id'
organization_id = 'your-organization-id'

# Enable VPC Service Controls
response = client.update_organization_settings(
    organization_settings={
        'name': f'organizations/{organization_id}/organizationSettings',
        'enable_vpc_service_controls': True
    }
)

print('VPC Service Controls enabled successfully.')

  2. Implement Pub/Sub access controls:

    • Use the google-cloud-pubsub library to implement access controls for your Pub/Sub topics and subscriptions.
    • Here’s an example Python script to create a new topic with access controls:
    from google.cloud import pubsub_v1

publisher = pubsub_v1.PublisherClient()

# Set the project ID and topic name
project_id = 'your-project-id'
topic_name = 'your-topic-name'

# Create a new topic with access controls
topic_path = publisher.topic_path(project_id, topic_name)
topic = publisher.create_topic(request={"name": topic_path, "labels": {"access_level": "private"}})

print(f'Topic {topic.name} created successfully with access controls.')

  3. Monitor and analyze Pub/Sub logs:

    • Use the google-cloud-logging library to monitor and analyze the logs generated by Pub/Sub.
    • Here’s an example Python script to retrieve and analyze Pub/Sub logs:
    from google.cloud import logging

client = logging.Client()

# Set the project ID and filter for Pub/Sub logs
project_id = 'your-project-id'
filter_str = 'logName:"projects/{project_id}/logs/cloudaudit.googleapis.com%2Fdata_access"'

# Retrieve and analyze Pub/Sub logs
logs = client.list_entries(filter_=filter_str)
for log in logs:
    print(f'Log entry: {log.payload}')

Please note that you need to install the required libraries (google-cloud-securitycenter, google-cloud-pubsub, google-cloud-logging) using pip before running these scripts.