Cis Azure Compute 2.9

Ensure App Service Environment has TLS 1.0 and 1.1 disabled

Description

The TLS (Transport Layer Security) protocol secures the transmission of data over the internet using standard encryption technology. TLS versions 1.0 and 1.1 have been deprecated, and their use is generally discouraged. Disable all inbound TLS 1.0 and TLS 1.1 traffic for all the apps in an App Service Environment.

Rationale

TLS 1.0 and 1.1 are outdated and vulnerable to security risks.

Impact

Disallowing TLS 1.0 and 1.1 may affect compatibility with clients and backend services.

Audit Procedure

Using Azure Portal

1. Go to App Service Environments.
2. Click the name of an App Service Environment.
3. Under Settings, click Configuration.
4. Ensure that Allow TLS 1.0 and 1.1 is set to Off.
5. Repeat steps 1-4 for each App Service Environment.

Using Azure CLI

Run the following command to list App Service Environments:

az appservice ase list

For each App Service Environment, ensure that clusterSettings includes:

{
  "name": "DisableTls1.0",
  "value": "1"
}

Expected Result

The clusterSettings should include a DisableTls1.0 setting with value "1". In the portal, Allow TLS 1.0 and 1.1 should be set to Off.

Remediation

Using Azure Portal

1. Go to App Service Environments.
2. Click the name of an App Service Environment.
3. Under Settings, click Configuration.
4. Next to Allow TLS 1.0 and 1.1, click the radio button next to Off.
5. Click Save.
6. Click Continue.
7. Repeat steps 1-6 for each App Service Environment requiring remediation.

Default Value

TLS 1.0 and 1.1 are allowed by default.

References

1. https://learn.microsoft.com/en-us/azure/app-service/environment/app-service-app-service-environment-custom-settings
2. https://learn.microsoft.com/en-us/cli/azure/appservice/ase

Profile

Level 1 | Automated