Ensure that 'Allow Blob Anonymous Access' is set to 'Disabled'

HighLevel 1Manual reviewazure

Description

The Azure Storage setting ‘Allow Blob Anonymous Access’ (aka "allowBlobPublicAccess") controls whether anonymous access is allowed for blob data in a storage account. When this property is set to True, it enables public read access to blob data, which can be convenient for sharing data but may carry security risks. When set to False, it disallows public access to blob data, providing a more secure storage environment. If "Allow Blob Anonymous Access" is enabled, blobs can be accessed by adding the blob name to the URL to see the contents. An attacker can enumerate a blob using methods, such as brute force, and access them. Exfiltration of data by brute force enumeration of items from a storage account may occur if this setting is set to 'Enabled'.

How it is checked

Audit method: Manual review

This recommendation cannot be checked automatically. A scan lists it with these instructions when you pass --include-manual.

Audit from Azure Portal 1. Go to Storage accounts. 2. For each storage account, under Settings, select Configuration. 3. Confirm Allow Blob Anonymous Access is set to Disabled. Audit from Azure CLI For each storage account, confirm anonymous blob access is disabled: az storage account show \ --name <storage-account> \ --resource-group <resource-group> \ --query allowBlobPublicAccess \ --output tsv A result of false is compliant; true is non-compliant. Audit from PowerShell (Get-AzStorageAccount -ResourceGroupName <resource-group> -Name <storage- account>).AllowBlobPublicAccess False is compliant; True is non-compliant. Audit from Azure Policy If referencing a digital copy of this Benchmark, clicking a Policy ID will open a link to the associated Policy definition in Azure. If referencing a printed copy, you can search Policy IDs from this URL: https://portal.azure.com/#view/Microsoft_Azure_Policy/PolicyMenuBlade/~/Definitions - Policy ID: 4fa4b6c0-31ca-4c0d-b10d-24b96f62a751 - Name: 'Storage account public access should be disallowed'

How it is fixed

Fix method: Guidance or infrastructure patch

Remediate from Azure Portal 1. Go to Storage accounts. 2. For each storage account, under Settings, select Configuration. 3. Set Allow Blob Anonymous Access to Disabled. 4. Select Save. Remediate from Azure CLI az storage account update --name <storage-account> --resource-group <resource-group> --allow-blob-public-access false Remediate from PowerShell Set-AzStorageAccount -ResourceGroupName <resource-group> -Name <storage- account> -AllowBlobPublicAccess $false

Properties

Operating systems: Any
Tags: access-controlazurecloudstorage
Reference: CIS Microsoft Azure Storage Services Benchmark v2.0.0 - 16.13 Ensure that 'Allow Blob Anonymous Access' is set to 'Disabled'