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Event Information

  1. The google.pubsub.v1.Subscriber.Seek event in GCP for Pubsub refers to the action of seeking or setting the position of a subscriber’s cursor in a Pubsub subscription.
  2. This event is triggered when a subscriber explicitly requests to move the cursor to a specific point in the message stream of a subscription.
  3. By using the Seek event, subscribers can control the flow of messages they receive, allowing them to skip or replay messages based on their specific requirements or business logic.

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Examples

  1. Unauthorized access: If the security of google.pubsub.v1.Subscriber.Seek is impacted, it could potentially allow unauthorized users to seek messages in a Pubsub subscription. This could lead to sensitive data being accessed by unauthorized individuals, resulting in a breach of data confidentiality.
  2. Message tampering: A security impact on google.pubsub.v1.Subscriber.Seek could also enable attackers to tamper with messages in a Pubsub subscription. This could result in the modification or manipulation of critical data, leading to potential integrity issues and incorrect processing of messages.
  3. Denial of Service (DoS): If the security of google.pubsub.v1.Subscriber.Seek is compromised, it could be exploited to launch a DoS attack on the Pubsub system. Attackers could flood the system with seek requests, overwhelming the infrastructure and causing service disruptions for legitimate users. This could result in a loss of availability and impact the overall reliability of the Pubsub service.

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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, to store the audit logs.
    • 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 VPC Service Perimeter or select an existing one that includes the Pub/Sub resources.
    • Configure the allowed APIs and services within the perimeter to only include the necessary ones for Pub/Sub.
    • Specify the authorized networks that can access the Pub/Sub resources.
    • Save the changes and apply the VPC Service Perimeter.
  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 appropriate roles to users, groups, or service accounts based on their responsibilities and access requirements.
    • Ensure that the principle of least privilege is followed, granting only the necessary permissions for Pub/Sub operations.
    • Regularly review and update the IAM roles and permissions as needed to maintain security and compliance.
Note: The above steps are high-level instructions and may vary based on the specific GCP Console interface and version. It is recommended to refer to the official GCP documentation for detailed and up-to-date instructions.

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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": [
    {
      "auditLogConfigs": [
        {
          "logType": "DATA_READ",
          "exemptedMembers": []
        },
        {
          "logType": "DATA_WRITE",
          "exemptedMembers": []
        }
      ],
      "service": "pubsub.googleapis.com"
    }
  ],
  "bindings": [
    {
      "role": "roles/pubsub.publisher",
      "members": [
        "user:<USER_EMAIL>"
      ]
    }
  ]
}
    • Replace <USER_EMAIL> with the email address of the user who should have the pubsub.publisher role.
  2. Implement VPC Service Controls for Pub/Sub:
    • Use the following command to create a VPC Service Controls perimeter for Pub/Sub: 
      gcloud access-context-manager perimeters create <PERIMETER_NAME> --resources=pubsub.googleapis.com/projects/<PROJECT_ID>/topics/*
    • Replace <PERIMETER_NAME> with a name for the perimeter and <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 for, <PROJECT_ID> with your GCP project ID, <KEY_RING_NAME> with the name of the key ring, and <CRYPTO_KEY_NAME> with the name of the crypto key.
Please note that the above commands are examples and may need to be modified based on your specific requirements and configurations.

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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'

# Set the VPC Service Controls configuration
vpc_service_controls = {
    'project': f'projects/{project_id}',
    'servicePerimeters': [
        {
            'name': f'projects/{project_id}/servicePerimeters/default',
            'status': 'ACTIVE',
            'resources': [
                'pubsub.googleapis.com'
            ],
            'restrictedServices': [
                'pubsub.googleapis.com'
            ]
        }
    ]
}

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

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'

# Set the IAM policy for the topic
policy = {
    'bindings': [
        {
            'role': 'roles/pubsub.publisher',
            'members': [
                'serviceAccount:[email protected]'
            ]
        }
    ]
}

# Create the topic with access controls
topic_path = publisher.topic_path(project_id, topic_name)
topic = publisher.create_topic(request={'name': topic_path, 'labels': {'access': 'restricted'}})
publisher.set_iam_policy(request={'resource': topic.name, 'policy': policy})

print('Topic created successfully with access controls.')
  3. Implement Pub/Sub message encryption:
    • Use the google-cloud-kms library to encrypt and decrypt Pub/Sub messages using Cloud KMS.
    • Here’s an example Python script to encrypt and decrypt Pub/Sub messages:
    from google.cloud import kms_v1

kms_client = kms_v1.KeyManagementServiceClient()

# Set the project ID and location
project_id = 'your-project-id'
location = 'global'

# Set the key ring and key name
key_ring_id = 'your-key-ring-id'
key_id = 'your-key-id'

# Encrypt a message
plaintext_message = 'your-message'
key_name = kms_client.crypto_key_path_path(project_id, location, key_ring_id, key_id)
response = kms_client.encrypt(request={'name': key_name, 'plaintext': plaintext_message})
ciphertext_message = response.ciphertext

# Decrypt a message
response = kms_client.decrypt(request={'name': key_name, 'ciphertext': ciphertext_message})
decrypted_message = response.plaintext

print(f'Encrypted message: {ciphertext_message}')
print(f'Decrypted message: {decrypted_message}')
Please note that you need to replace the placeholders (your-project-id, your-organization-id, [email protected], your-topic-name, your-key-ring-id, your-key-id, your-message) with your actual values in the above scripts.