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Event Information

  1. The google.pubsub.v1.Subscriber.ModifyAckDeadline event in GCP for Pubsub refers to an event where the acknowledgement deadline for a message in a subscription is modified.
  2. This event occurs when a subscriber client sends a ModifyAckDeadline request to the Pubsub service in order to extend or reduce the acknowledgement deadline for a specific message.
  3. Modifying the acknowledgement deadline allows the subscriber more time to process the message before it is considered unacknowledged and redelivered, helping to ensure reliable message processing in Pubsub.

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Examples

  1. Unauthorized modification of acknowledgement deadlines: If security is impacted with google.pubsub.v1.Subscriber.ModifyAckDeadline in GCP Pub/Sub, it could potentially allow unauthorized users to modify the acknowledgement deadlines of messages. This could lead to messages being processed multiple times or not being processed at all, resulting in data integrity and consistency issues.
  2. Denial of Service (DoS) attacks: Exploiting the ModifyAckDeadline API could allow an attacker to flood the system with requests to modify the acknowledgement deadlines, causing a Denial of Service (DoS) attack. This could result in the system becoming unresponsive or unavailable, impacting the availability and reliability of the Pub/Sub service.
  3. Privilege escalation: If security is compromised with the ModifyAckDeadline API, an attacker could potentially escalate their privileges and gain unauthorized access to other resources within the GCP environment. This could lead to further data breaches, unauthorized data access, and potential compromise of other sensitive information.

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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 necessary 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 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'

# 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.