Description:
Periodically, newer versions are released for Java software either due to security flaws or to include additional functionality. Using the latest Java version for web apps is recommended in order to take advantage of security fixes, if any, and/or new functionalities of the newer version.
Rationale:
Newer versions may contain security enhancements and additional functionality. Using the latest software version is recommended in order to take advantage of enhancements and new capabilities. With each software installation, organizations need to determine if a given update meets their requirements. They must also verify the compatibility and support provided for any additional software against the update revision that is selected.
Impact:
If your app is written using version-dependent features or libraries, they may not be available on the latest version. If you wish to upgrade, research the impact thoroughly. Upgrading may have unforeseen consequences that could result in downtime.
Audit:
From Azure Portal
1. Login to Azure Portal using https://portal.azure.com
2. Go to App Services
3. Click on each App
4. Under Settings section, click on Configuration
5. Click on the General settings pane and ensure that for a Stack of Java the Major Version and Minor Version reflect the latest stable and supported release, and that the Java web server version is set to the auto-update option.
NOTE: No action is required if Java version is set to Off, as Java is not used by your web app.
From Azure CLI
To check Java version for an existing app, run the following command,
az webapp config show --resource-group <RESOURCE_GROUP_NAME> --name
<APP_NAME> --query "{LinuxFxVersion:linuxFxVersion,
WindowsFxVersion:windowsFxVersion, JavaVersion:javaVersion,
JavaContainerVersion:javaContainerVersion, JavaContainer:javaContainer}"
The output should return the latest available version of Java (if java is being used for the web application being audited).
From PowerShell
For each application, store the application information within an object, and then interrogate the SiteConfig information for that application object.
$app = Get-AzWebApp -Name <app name> -ResourceGroup <resource group name>
$app.SiteConfig |Select-Object LinuxFXVersion, WindowsFxVersion, JavaVersion,
JavaContainerVersion, JavaContainer
Ensure the Java version used within the application is a currently supported version (if java is being used for the web application being audited).
Remediation:
From Azure Portal
1. Login to Azure Portal using https://portal.azure.com
2. Go to App Services
3. Click on each App
4. Under Settings section, click on Configuration
5. Click on the General settings pane and ensure that for a Stack of Java the Major Version and Minor Version reflect the latest stable and supported release, and that the Java web server version is set to the auto-update option.
NOTE: No action is required if Java version is set to Off, as Java is not used by your web app.
From Azure CLI
To see the list of supported runtimes:
az webapp list-runtimes
To set latest Java version for an existing app, run the following command:
az webapp config set --resource-group <RESOURCE_GROUP_NAME> --name <APP_NAME>
[--java-version <JAVA_VERSION> --java-container <JAVA_CONTAINER> --javacontainer-version <JAVA_CONTAINER_VERSION> [--windows-fx-version <java
runtime version>] [--linux-fx-version <java runtime version version>]
If creating a new web application to use a currently supported version of Java, run the following commands.To create an app service plan:
az appservice plan create --resource-group <resource group name> --name <plan
name> --location <location> [--is-linux --number-of-workers <int> --sku
<pricing tier>] [--hyper-v --sku <pricing tier>]
Get the app service plan ID:
az appservice plan list --query "[].{Name:name, ID:id, SKU:sku,
Location:location}"
To create a new Java web application using the retrieved app service ID:
az webapp create --resource-group <resource group name> --plan <app service
plan ID> --name <app name> [--linux-fx-version <java run time version>] [--
windows-fx-version <java run time version>]
From PowerShell
As of this writing, there is no way to update an existing application's SiteConfig or set a new application's SiteConfig settings during creation via PowerShell.
Default Value:
The default setting is whichever setting was chosen in the creation of the webapp.
References:
1. https://docs.microsoft.com/en-us/azure/app-service/web-sites-configure#generalsettings
4. https://www.oracle.com/java/technologies/downloads/#java11