Microsoft AzureOverview
Client certificates allow for the app to request a certificate for incoming requests. Only clients that have a valid certificate will be able to reach the app.
Rationale
The TLS mutual authentication technique in enterprise environments ensures the authenticity of clients to the server. If incoming client certificates are enabled, then only an authenticated client who has valid certificates can access the app.
Impact
Utilizing and maintaining client certificates will require additional work to obtain and managed replacement and key rotation.
Remediation guidance
From Azure Console
- Go to
App Services - For each app, under
Settings, selectConfiguration - Go to
General settings - Under
Incoming client certificates, setClient certificate modetoRequire
Using Azure Command Line Interface
To set Incoming client certificates value for an existing app, run the following command:
az webapp update --resource-group <resourceGroup> --name <applicationName> --set clientCertEnabled=true
Default Value
By default, incoming client certificates will be disabled when a new app is created using the command-line tool or Azure Portal console.
References
Service-wide remediation
Recommended when many resources are affected: fix the platform baseline first so new resources inherit the secure setting, then remediate the existing flagged resources in batches.
Azure
Use management group or subscription Azure Policy assignments, remediation tasks where supported, landing-zone standards, and IaC modules so drift is prevented at scale.
Operational rollout
- Fix the baseline first at the account, subscription, project, cluster, or tenant scope that owns this control.
- Remediate the currently affected resources in batches, starting with internet-exposed and production assets.
- Re-scan and track approved exceptions with an owner and expiry date.
Query logic
These are the stored checks tied to this control.
The web app has 'Client Certificates (Incoming client certificates)' set to 'On'
Connectors
Covered asset types
Expected check: eq []
{sites(where:{clientCertEnabled_NOT:true}){...AssetFragment}}
