Finding correct permissions for custom roles in Azure RBAC

Finding correct permissions for custom roles in Azure RBAC

In Azure you can assign user, group and services access to different resources. It is of course a good idea to assign as exact permissions as possible to each user, group or service. Too many permissions mean that for example a user can affect more resources than planned and expose a larger attack surface. Too few permissions mean that the user can’t do their job in an effective way. With Azure Role-Based Access Control (RBAC) you can assign each user, group or service only the amount of permissions they need to perform their job. Azure RBAC comes with many built-in roles, for more information about the built-in roles click here.

In some scenarios, the built-in roles are not suitable to the scenario. That is when we can build our own roles 😊 Custom roles can be assigned users, groups and services, just like the built-in roles. They can also be shared among all subscriptions that use the same Azure AD. I wrote a blog post about custom roles in October, Setting up team permissions with custom RBAC role and ARM policy. That blog post cover everything around getting started with custom roles.

But sometimes it is difficult to find correct operations for your custom roles. For example, in this scenario, a user is assigned the built-in Contributor role to a resource group. The user can then create/edit/delete any resource within the resource group, but cannot delete the resource group or change access to it. But the user also need permissions to administrate locks on resources in the resource group.  There is no lock administrator role built-in instead we need to build it.

Finding correct Azure operations for locks administration is made easy with the following Powershell script

$collection = Get-AzureRmProviderOperation *
foreach ($item in $collection)
{
    $desc = $item.Description
    If ($desc -like "*locks*")
        {
            $item.Operation
        }
}

The script goes through all providers and operations in Azure and checks for each operation that have “locks” in the description.

We can then use the locks operations we just found to build a new custom RBAC role, described in the blog post around RBAC from October (link earlier in this post). As you can see in the figure below the role is assigned to the entire subscription. By doing this it is easy to use the role on multiple places within the subscription.

In this blog post we have seen how we can find operators for Azure custom RBAC roles. Each operator control a task or action that a user, group or service can do. Assigning the correct amount of permissions to a role will both increase security and the possibilities to effectively work. Try to use groups instead of users when assigning permissions, as you would do in your Windows Server Active Directory. Assigning permissions to groups instead of users will make administration easier.

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