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Event Information

  1. The google.pubsub.v1.Subscriber.Acknowledge event in GCP for Pubsub indicates that a message has been successfully processed and acknowledged by the subscriber.
  2. This event is triggered when the subscriber application sends an acknowledgment to the Pubsub service, confirming that it has successfully processed a message.
  3. Acknowledging a message ensures that it will not be redelivered to the subscriber, preventing duplicate processing and ensuring reliable message delivery.

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Examples

  1. Unauthorized access: If security is impacted with google.pubsub.v1.Subscriber.Acknowledge in GCP for Pubsub, it could indicate that unauthorized individuals or entities have gained access to the subscriber’s acknowledge functionality. This could potentially allow them to manipulate or tamper with the acknowledgment process, leading to message loss, duplication, or unauthorized access to sensitive data.

  2. Message spoofing: Another security concern could be message spoofing, where an attacker impersonates a legitimate subscriber and sends false acknowledgments to the Pubsub service. This could result in the system incorrectly assuming that certain messages have been successfully processed, leading to potential data integrity issues or unauthorized access to sensitive information.

  3. Denial of Service (DoS) attacks: A compromised acknowledge functionality could also be exploited to launch DoS attacks against the Pubsub service. By flooding the system with a large number of false acknowledgments, an attacker could overwhelm the service’s resources, causing it to become unresponsive or unavailable for legitimate users. This could result in service disruptions and impact the availability of the application relying on Pubsub for message processing.

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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

  1. Enable audit logging for GCP Pub/Sub:

    • Use the following command to enable audit logging for Pub/Sub: 
      gcloud pubsub topics set-iam-policy [TOPIC_NAME] --audit-log-config=LOGS_READ

  2. Restrict access to Pub/Sub topics:

    • Use the following command to update the IAM policy for a Pub/Sub topic and restrict access: 
      gcloud pubsub topics set-iam-policy [TOPIC_NAME] [POLICY_FILE]

  3. Enable VPC Service Controls for Pub/Sub:

    • Use the following command to enable VPC Service Controls for Pub/Sub: 
      gcloud services vpc-peerings add-iam-policy-binding \
--service=servicenetworking.googleapis.com \
--member=[MEMBER] \
--role=roles/servicenetworking.networksViewer

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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 Pub/Sub activity using Cloud Monitoring:

    • Use the google-cloud-monitoring library to monitor Pub/Sub activity and set up alerts for any suspicious or unauthorized events.
    • Here’s an example Python script to create a new alert policy for Pub/Sub:
    from google.cloud import monitoring_v3

client = monitoring_v3.AlertPolicyServiceClient()

# Set the project ID and alert policy details
project_id = 'your-project-id'
policy_name = 'your-policy-name'
topic_name = 'projects/your-project-id/topics/your-topic-name'

# Create a new alert policy for Pub/Sub
policy = client.create_alert_policy(
    name=f'projects/{project_id}/alertPolicies/{policy_name}',
    alert_policy={
        'display_name': policy_name,
        'conditions': [
            {
                'display_name': 'Pub/Sub Unauthorized Access',
                'condition_threshold': {
                    'filter': f'resource.type="pubsub_topic" AND protoPayload.methodName="google.pubsub.v1.Publisher.CreateTopic" AND protoPayload.resourceName="{topic_name}"',
                    'comparison': 'COMPARISON_GT',
                    'threshold_value': 0
                },
                'duration': '60s',
                'trigger': {
                    'count': 1
                }
            }
        ],
        'notification_channels': []
    }
)

print(f'Alert policy {policy.name} created successfully for Pub/Sub.')

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