Cis Azure Database 3.6

3.6 Ensure the firewall does not allow all network traffic (Automated)

Profile Applicability

• Level 1

Description

Do not allow all network traffic. Restrict access to specific IP addresses or ranges.

Rationale

Allowing all network traffic limits the effectiveness of a firewall.

Impact

Administrative effort to identify and maintain the list of IP addresses and ranges requiring access to the account.

Audit Procedure

Audit from Azure Portal

1. Go to Azure Cosmos DB.
2. Select the name of an Azure Cosmos DB account.
3. Under Settings, select Networking.
4. Under Public access, if Public network access is set to Selected networks, ensure 0.0.0.0 is not listed under Firewall > IPs.
5. Repeat steps 1-4 for each account.

Audit from Azure CLI

Run the following command to list Azure Cosmos DB accounts:

az cosmosdb list

For each account, run the following command to get the list of allowed IP addresses:

az cosmosdb show --resource-group <resource-group> --name <cosmos-db> --query ipRules

Ensure that the response does not contain "0.0.0.0".

Audit from PowerShell

Run the following command to get Azure Cosmos DB accounts for a given resource group:

Get-AzCosmosDBAccount -ResourceGroupName <resource-group>

Run the following command to get the account with a given name:

$cosmosdb = Get-AzCosmosDBAccount -ResourceGroupName <resource-group> -Name <cosmos-db>

Run the following command to get the list of allowed IP addresses:

$cosmosdb.IpRules

Ensure that the response does not contain 0.0.0.0.

Repeat for each account.

Audit from Azure Policy

• Policy ID: 12339a85-a25c-4f17-9f82-4766f13f5c4c - Name: 'Azure Cosmos DB accounts should not allow traffic from all Azure data centers'

Expected Result

The IP rules should not contain 0.0.0.0, which would allow all network traffic.

Remediation

Remediate from Azure Portal

1. Go to Azure Cosmos DB.
2. Select the name of an Azure Cosmos DB account.
3. Under Settings, select Networking.
4. Under Public access, Firewall > IPs, select the Delete icon next to 0.0.0.0.
5. Select Save.
6. Repeat steps 1-5 for each account requiring remediation.

Remediate from Azure CLI

For each account requiring remediation, run the following command to update the list of allowed IP addresses, excluding 0.0.0.0:

az cosmosdb update --resource-group <resource-group> --name <cosmos-db-account> --ip-range-filter <comma-separated-list-of-allowed-ip-addresses>

Remediate from PowerShell

For each account requiring remediation, run the following command to update the list of allowed IP addresses, excluding 0.0.0.0:

Update-AzCosmosDBAccount -ResourceGroupName <resource-group> -Name <cosmos-db-account> -IpRule <comma-separated-list-of-allowed-ip-addresses>

Default Value

By default, the firewall does not allow all network traffic.

Additional Information

Setting publicNetworkAccess to Disabled takes precedence over Accept connections from within public Azure datacenters.

References

1. https://learn.microsoft.com/en-gb/azure/cosmos-db/how-to-configure-firewall#allow-requests-from-global-azure-datacenters-or-other-sources-within-azure

CIS Controls

MITRE ATT&CK Mappings