Cis Azure Compute 2.1.3

Ensure 'PHP version' is currently supported (if in use)

Description

Periodically, older versions of PHP may be deprecated and no longer supported. Using a supported version of PHP for App Service apps is recommended to avoid potential unpatched vulnerabilities.

Rationale

Deprecated and unsupported versions of programming and scripting languages can present vulnerabilities which may not be addressed or may not be addressable.

Impact

If your app is written using version-dependent features or libraries, they may not be available on more recent versions. If you wish to update, research the impact thoroughly.

Audit Procedure

Using Azure Portal

1. Go to App Services.
2. Click the name of an app.
3. Under Settings, click Configuration.
4. In the General settings pane, ensure that for a Stack of PHP, the Major version and Minor version reflect a currently supported release.
5. Repeat steps 1-4 for each app.

Using Azure CLI

Run the following command to list apps:

az webapp list

For each app, run the following command to get the PHP version:

az webapp config show --resource-group <resource-group-name> --name <app-name> --query "{LinuxFxVersion:linuxFxVersion,PhpVersion:phpVersion}"

If PHP is in use, ensure the version is currently supported.

Using Azure PowerShell

Run the following command to list apps:

Get-AzWebApp

Run the following command to get the app in a resource group with a given name:

$app = Get-AzWebApp -ResourceGroupName <resource-group-name> -Name <app-name>

Run the following command to get the PHP version:

$app.SiteConfig | select-object LinuxFXVersion, PhpVersion

If PHP is in use, ensure the version is currently supported. Repeat for each app.

Expected Result

The PHP version in use should be a currently supported release as listed at https://www.php.net/supported-versions.php.

Remediation

Using Azure Portal

1. Go to App Services.
2. Click the name of an app.
3. Under Settings, click Configuration.
4. In the General settings pane, for a Stack of PHP, set the Major version and Minor version to a currently supported release.
5. Click Save.
6. Click Continue.
7. Repeat steps 1-6 for each app requiring remediation.

Note: No action is required if PHP is not in use.

Using Azure CLI

Run the following command to list supported runtimes:

az webapp list-runtimes

For each app requiring remediation, run the following command with the appropriate parameters to update the PHP version:

az webapp config set --resource-group <resource-group-name> --name <app-name> [--linux-fx-version <php-runtime-version>][--php-version <php-version>]

Using Azure PowerShell

For each app requiring remediation, run the following command to update the PHP version:

Set-AzWebApp -ResourceGroupName <resource-group-name> -Name <app-name> -phpVersion <php-version>

Note: Currently, there is no way to update an app's Linux FX Version setting using PowerShell.

Default Value

The version is selected during creation.

References

1. https://learn.microsoft.com/en-us/azure/app-service/configure-common#general-settings
2. https://learn.microsoft.com/en-us/security/benchmark/azure/security-controls-v3-posture-vulnerability-management#pv-7-rapidly-and-automatically-remediate-software-vulnerabilities
3. https://learn.microsoft.com/en-us/security/benchmark/azure/security-controls-v3-posture-vulnerability-management#pv-3-establish-secure-configurations-for-compute-resources
4. https://www.php.net/supported-versions.php
5. https://learn.microsoft.com/en-us/cli/azure/webapp
6. https://learn.microsoft.com/en-us/powershell/module/az.websites/get-azwebapp
7. https://learn.microsoft.com/en-us/powershell/module/az.websites/set-azwebapp

Profile

Level 1 | Manual