cyberstrikeus Ensure configuration is routed through the virtual network integration
Description
By default, configuration traffic for function apps goes directly over the public route. Container image pulls and content sharing can be routed through the virtual network integration.
This recommendation should be applied after integrating a function app with a virtual network.
Rationale
Route container image pulls and content sharing through a virtual network integration for increased security and control.
Impact
Additional configuration may be required to ensure that traffic is routed properly.
Audit Procedure
Using Azure CLI
Run the following command to list function apps:
az functionapp list
For each function app, run the following command to get the container image share and content share settings:
az functionapp show --resource-group <resource-group-name> --name <function-app-name> --query "[vnetImagePullEnabled,vnetContentShareEnabled]"
Ensure that [true,true] is returned.
Using Azure Portal
There is no specific Azure Portal audit procedure documented for this control. Use the Azure CLI method.
Expected Result
Both vnetImagePullEnabled and vnetContentShareEnabled should return true ([true,true]).
Remediation
Using Azure CLI
For each function app requiring remediation, run the following command to route container image pulls and content sharing through the virtual network integration:
az resource update --resource-group <resource-group-name> --name <function-app-name> --resource-type "Microsoft.Web/sites" --set properties.vnetImagePullEnabled=true --set properties.vnetContentShareEnabled=true
Using Azure Portal
There is no specific Azure Portal remediation procedure documented for this control. Use the Azure CLI method.
Additional Information
In addition to configuring the routing for content sharing, you must also ensure that any firewall or Network Security Group configured on traffic from the subnet allow traffic to port 443 and 445.
Default Value
By default, configuration traffic goes directly over the public route.
References
- https://learn.microsoft.com/en-us/azure/app-service/overview-vnet-integration#routes
- https://learn.microsoft.com/en-us/azure/app-service/configure-vnet-integration-routing#configure-configuration-routing
- https://learn.microsoft.com/en-us/cli/azure/functionapp
- https://learn.microsoft.com/en-us/cli/azure/resource
Profile
Level 2 | Automated