Cis Azure Compute 2.3.2

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

Description

Periodically, older versions of Python may be deprecated and no longer supported. Using a supported version of Python for function 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 or Function App.
2. Click the name of a function app.
3. Under Settings, click Configuration.
4. In the General settings pane, ensure that for a Stack of Python, the Python Version reflects a currently supported release.
5. Repeat steps 1-4 for each function app.

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 Python version:

az functionapp config show --resource-group <resource-group-name> --name <app-name> --query "{LinuxFxVersion:linuxFxVersion,PythonVersion:pythonVersion}"

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

Using Azure PowerShell

Run the following command to list function apps:

Get-AzFunctionApp

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

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

Run the following command to get the Python version:

$app.SiteConfig | Select-Object LinuxFXVersion, PythonVersion

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

Take note of the currently supported versions (given a status of "security") of Python here: https://devguide.python.org/versions/

Expected Result

If Python is in use, the Python version should reflect a currently supported release.

Remediation

Using Azure Portal

1. Go to App Services or Function App.
2. Click the name of a function app.
3. Under Settings, click Configuration.
4. In the General settings pane, for a Stack of Python, set the Python Version to a currently supported release.
5. Click Save.
6. Click Continue.
7. Repeat steps 1-6 for each function app requiring remediation.

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

Using Azure CLI

Run the following command to list supported runtimes:

az functionapp list-runtimes

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

az functionapp config set --resource-group <resource-group-name> --name <app-name> --linux-fx-version "PYTHON|<version>"

Default Value

The version is selected during creation.

References

1. https://learn.microsoft.com/en-us/azure/app-service/configure-common#configure-language-stack-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://devguide.python.org/versions/
5. https://learn.microsoft.com/en-us/cli/azure/functionapp
6. https://learn.microsoft.com/en-us/powershell/module/az.functions/get-azfunctionapp

Profile

Level 1 | Manual