Azure Zero Trust approach with Perimeter-based networks and Policy as Code (PaC)

The Azure Zero Trust approach is a security model that assumes that all network traffic is potentially malicious and requires strict access controls and continuous verification of identity and device trust. It is designed to replace the traditional perimeter-based network security model, in which trusted users and devices are granted access to internal resources based on their location within the network perimeter.

In the Azure Zero Trust approach, access to resources is granted based on the identity of the user or device, the context of the request (such as the location, time of day, and type of device), and the risk level of the requested resource. This approach is implemented using a combination of Azure Identity and Access Management (IAM) technologies, including Azure AD, Azure AD Identity Protection, and Azure AD Conditional Access.

To implement the Azure Zero Trust approach, you can follow these steps:

  1. Implement Azure AD for identity and access management: Use Azure AD to manage user identities and enable single sign-on (SSO) to all of your cloud and on-premises applications.
  2. Enable Azure AD Identity Protection: Use Azure AD Identity Protection to monitor for and alert on suspicious user activity, such as unusual sign-in patterns or the use of stolen credentials.
  3. Configure Azure AD Conditional Access: Use Azure AD Conditional Access to set policies that grant or deny access to resources based on the risk level of the request, the context of the request, and the user’s identity.

By following these steps, you can implement a zero trust security model in Azure and better protect your resources from malicious threats.

Azure PIM (Privileged Identity management)

Azure Privileged Identity Management (PIM) is a security feature of Azure AD that helps you to manage, control, and monitor access to sensitive resources in your Azure subscription. It allows you to assign temporary, just-in-time (JIT) access to privileged roles, enabling users to perform privileged tasks only when they are needed, and providing a full audit trail of their actions.

With Azure PIM, you can:

  • Assign just-in-time access to privileged roles: Enable users to request temporary, time-limited access to privileged roles, such as Global Administrator or Resource Manager Contributor, when they need to perform specific tasks.
  • Monitor and control access to sensitive resources: Use Azure PIM to monitor and control access to sensitive resources, such as virtual machines and storage accounts, and receive alerts when suspicious activity is detected.
  • Implement least privilege principles: Use Azure PIM to enforce the principle of least privilege, which means granting users only the permissions they need to perform their duties, and revoking those permissions when they are no longer needed.
  • Enhance security and compliance: Use Azure PIM to enhance security and compliance by implementing a least privilege model and providing a full audit trail of user actions.

To use Azure PIM, you will need to have an Azure AD Premium P2 license. You can then enable PIM and assign users to the Azure AD PIM role to manage access to privileged roles and resources.

Policy as Code (PaC) with IaC (Infrastructure as Code)

Policy as code (PaC) is a software engineering approach to defining and enforcing policies that govern the configuration and operation of infrastructure and applications. PaC frameworks provide a set of tools and libraries that enable you to define policies as code, automate policy enforcement, and track compliance with policies.

Some examples of PaC frameworks include:

  • Terraform Sentinel: A policy as code framework for Terraform, developed by HashiCorp. It allows you to define policies using the Sentinel language and enforce them as part of your Terraform workflows.
  • AWS Config Rules: A service provided by Amazon Web Services (AWS) that enables you to define and enforce policies for your AWS resources using the AWS CloudFormation template language.
  • Open Policy Agent (OPA): An open source policy engine that enables you to define policies using the Rego language and enforce them across a wide range of platforms and technologies, including Kubernetes, Envoy, and Terraform.
  • Cloud Custodian: An open source policy as code framework for AWS, developed by Capital One. It allows you to define policies using YAML and enforce them using AWS Lambda functions.

Each PaC framework has its own set of features and capabilities, and which one you choose will depend on your specific needs and requirements.

Terraform Sentinal

Terraform Sentinel is a policy as code framework for Terraform that allows you to define and enforce policies using the Sentinel language. Here is an example of a Sentinel policy that enforces the principle of least privilege by requiring that all users be granted the minimum permissions necessary to perform their duties:

import "tfplan"

# Allow users to assume the least privilege role necessary for their job
minimum_permissions = {
  "user1": ["read"],
  "user2": ["read", "write"],
  "user3": ["read", "write", "create"],

# Define the policy
policy "minimum-permissions" {
  # Enforce the policy on all resources
  resource "*" {
    # Check the permissions granted to each user
    for user, permissions in minimum_permissions {
      # If a user has been granted more permissions than necessary, fail the policy
      if length(permissions) < length(tfplan.policy_definition.permissions) {
        fail("User '" + user + "' has been granted more permissions than necessary")

This policy defines a mapping of users to the minimum permissions they should be granted, and then checks the permissions granted to each user in the Terraform plan to ensure that they do not exceed the minimum required for their job. If a user has been granted more permissions than necessary, the policy will fail.

To use this policy, you will need to save it to a file (e.g. “minimum-permissions.sentinel”) and include it in your Terraform configuration using the sentinel directive:

# Enforce the minimum permissions policy
sentinel "minimum-permissions" {
  # The path to the Sentinel policy file
  policy_file = "minimum-permissions.sentinel"

You can then run terraform plan as usual, and the Sentinel policy will be enforced as part of the planning process.

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