Tutorial / Cram Notes
Password-based Authentication (Client Secret)
This is the simplest form of authentication for service principals. When you create a service principal in Azure Active Directory (AAD), you have the option to generate a password or secret that will be used for authentication.
Steps to configure password-based authentication:
- Sign in to the Azure portal and navigate to Azure Active Directory.
- Go to ‘App registrations’ and select the application associated with the service principal or create a new registration.
- In the application panel, click on ‘Certificates & secrets’.
- Under ‘Client secrets’, click on ‘New client secret’.
- Provide a description for the client secret, choose an expiration period, and then click ‘Add’.
- Once the client secret is created, note the value generated as it won’t be displayed again.
Example:
az ad sp create-for-rbac –name {Service-Principal-Name}
This command creates a new service principal with a client secret and assigns it a default role.
Certificate-based Authentication
For environments requiring higher security standards, certificate-based authentication is recommended. Certificates are considered more secure because they are cryptographically signed by a trusted authority and are more difficult to compromise than a password.
Steps to configure certificate-based authentication:
- Generate a certificate (self-signed or issued by a Certificate Authority).
- Sign in to the Azure portal.
- Navigate to Azure Active Directory and select ‘App registrations’.
- Choose the application tied to the service principal.
- In the application panel, go to ‘Certificates & secrets’.
- Click on ‘Upload certificate’ and select the certificate file to upload.
- Once the certificate is uploaded, Azure AD will use it for authentication purposes.
Example:
$cert = New-SelfSignedCertificate -Subject “CN=ServicePrincipalName” -CertStoreLocation “Cert:\CurrentUser\My” -KeyExportPolicy Exportable -KeySpec Signature
New-AzADServicePrincipal -DisplayName ServicePrincipalName -CertValue $cert.RawData
These commands create a new self-signed certificate and then use it to create a new service principal.
Comparison of Authentication Methods
| Authentication Method | Level of Security | Expiry | Rotation Strategy | Use Case |
|---|---|---|---|---|
| Password (Client Secret) | Lower | Yes, based on the chosen period | Manual update of client secrets | Suitable for environments with a less strict security requirement |
| Certificate | Higher | Yes, based on the certificate validity period | Requires certificate renewal and update in Azure AD | Recommended for production environments and where automated processes require higher security |
Securing Service Principal Authentication
Regardless of the authentication method chosen, the following best practices help to ensure that your service principals remain secure:
- Rotate credentials regularly to limit the exposure window of a potential compromised credential.
- Use Azure Key Vault to securely store and manage client secrets and certificates.
- Limit the permissions granted to a service principal to only those that are necessary (principle of least privilege).
- Monitor the use of service principals with Azure AD audit logs.
By understanding the available methods and following the recommended steps and best practices, you can configure a secure authentication method for your service principal, thereby securing application access to Azure resources while complying with security policies and standards.
Practice Test with Explanation
True or False: When you create a service principal in Azure, it can only be associated with one authentication method at a time.
- False
A service principal in Azure can be associated with multiple authentication methods, such as a password (client secret) or a certificate.
The default validity period for a service principal password in Azure AD is ___________.
- A) 1 year
- B) 2 years
- C) Never expires
- D) 6 months
A) 1 year
The default validity period for a service principal password (client secret) in Azure Active Directory is 1 year.
True or False: Service principals in Azure can be used to grant specific permissions to a service or application within a particular scope.
- True
Service principals allow services or applications to access resources subject to the permissions granted to them, within a specified scope.
Which PowerShell cmdlet can be used to create a new service principal?
- A) New-AzureRmServicePrincipal
- B) Create-AzureADServicePrincipal
- C) New-AzureADServicePrincipal
- D) Add-AzureServicePrincipal
C) New-AzureADServicePrincipal
The PowerShell cmdlet New-AzureADServicePrincipal is used to create a new service principal in Azure.
True or False: Certificates used for service principal authentication cannot be uploaded to Azure through the Azure portal.
- False
Certificates can be uploaded to Azure and associated with a service principal through the Azure portal, Azure CLI, or Azure PowerShell.
In the context of an Azure service principal, what is a “client secret”?
- A) A unique identifier for the service principal
- B) An X.509 certificate
- C) A password used to authenticate the service principal
- D) A role assigned to the service principal
C) A password used to authenticate the service principal
A client secret is a password that is used to authenticate a service principal in Azure.
True or False: Azure Managed Identities can be used as an authentication method for service principals.
- False
Managed Identities are used to enable Azure services to authenticate to other services without credentials in the code, but they are not used as an authentication method for service principals.
What Azure service helps in rotating the secrets of a service principal automatically?
- A) Azure Active Directory
- B) Azure Key Vault
- C) Azure Security Center
- D) Azure Monitor
B) Azure Key Vault
Azure Key Vault can help automate the rotation of secrets for a service principal, providing enhanced security.
True or False: After you create a service principal in Azure, you cannot change its authentication method from a client secret to a certificate.
- False
You can change a service principal’s authentication method from a client secret to a certificate or vice versa after its creation.
The Azure CLI command to create a new service principal with a password is ___________.
- A) az ad sp create-for-rbac
- B) az sp create –password
- C) az ad sp create –secret
- D) az ad sp create-password
A) az ad sp create-for-rbac
The Azure CLI command `az ad sp create-for-rbac` is used to create a new service principal and configure its access to Azure resources. It often includes creating a password (client secret) if no certificate is specified.
True or False: You can assign a managed identity to a service principal to make use of Azure AD’s authentication features.
- False
A managed identity is itself an identity in Azure AD, which can be assigned to an Azure service, and is not assigned to a service principal.
Multiselect: Which of the following Azure tools/services can be used to assign an RBAC role to a service principal?
- A) Azure Portal
- B) Azure PowerShell
- C) Azure CLI
- D) Microsoft Graph API
A) Azure Portal, B) Azure PowerShell, C) Azure CLI, D) Microsoft Graph API
All the listed tools and services can be used to assign an RBAC (Role-Based Access Control) role to a service principal in Azure, providing the necessary permissions to access Azure resources.
Interview Questions
What is a service principal in Azure AD?
A service principal is an identity that an application uses to authenticate with Azure AD and access resources. It provides the application with the necessary permissions to access resources in Azure.
How is a service principal different from a user account?
A service principal is for an application, not a person, and it provides the application with the necessary permissions to access resources in Azure.
What is an app object in Azure AD?
An app object is an instance of an application that is registered with Azure AD. It represents the configuration and metadata of the application, including the URL for the application’s homepage and the identifier for the application.
How is an app object different from a service principal?
An app object represents the configuration and metadata of an application, while a service principal is the identity that an application uses to authenticate with Azure AD and access resources.
How are app objects and service principals related?
An app object represents an instance of an application, and a service principal is created automatically when the app object is created. The service principal provides the application with the necessary permissions to access resources in Azure.
What is a client ID?
A client ID is a unique identifier that is assigned to an application when it is registered with Azure AD. The client ID is used to identify the application when it requests access to resources in Azure.
What is a client secret?
A client secret is a string that is used by an application to authenticate with Azure AD and access resources. It is a password that is shared between the application and Azure AD.
How do you create a service principal for an application?
A service principal is created automatically when you register an application in Azure AD.
What permissions does a service principal have?
The permissions that a service principal has depend on the role that it is assigned in Azure AD. A service principal can be assigned roles that grant it access to specific resources and actions in Azure.
How do you manage service principals in Azure AD?
Service principals can be managed in the Azure portal or through the Azure AD PowerShell module. You can use these tools to view and manage the permissions that are assigned to a service principal, and to create and delete service principals.
This blog post was really helpful for understanding how to configure an authentication method for a service principal in Azure. Thanks!
I followed the steps in the blog, but I’m getting an authentication error when I try to test my service principal. Any ideas?
Great resource for AZ-500 exam preparation. Can anyone recommend more materials like this?
What authentication methods are best for securing a service principal used in production?
Your step-by-step guide is clear, but can you address how to handle the expiration of client secrets?
I’m preparing for the AZ-500 and found this post useful. Any other exam tips?
Fantastic post! Cleared up a lot of confusion I had.
I think there’s an error in the section on configuring permissions. Could anyone else verify?