Azure Security: Best Practices to improve Security Posture

The tendency to have more frequently solutions in the cloud and hybrid architectures requires you to adopt high security standards for your environment. But how do you get effective cloud security for Azure and what best practices you should follow? This article summarizes the key practices that you should use in Azure to ensure a high level of security and improve security postures.

MFA activation and restrictions for administrative access

For users with administrative rights, authentication should be enabled using administrative Multi-factor Authentication (MFA). In this regard it is very interesting to evaluate passwordless authentication mechanisms that require that the password be replaced with something that you own more something that you are or that you know.

Microsoft currently offers three distinct passwordless authentication scenarios:

Azure Active Directory provides the ability to enable MFA mechanisms, including passwordless authentication. MFA mechanisms based on text messages are easier to bypass, so it's good to target different Multi-factor authentication mechanisms or passwordless.

Minimize the number of people and their time, for administrative access to Azure resources, it is a practice to be adopted because it reduces the possibility of an attacker obtaining administrative access or an authorized user inadvertently affecting a specific resource. To enable authorized users to perform administrative actions, you can offer just-in-time privileged access (JIT) Azure and Azure AD resources. To do this, the Azure Active Directory service is adopted (Azure AD) Privileged Identity Management (PIM) which allows you to manage, controlling and monitoring access to company resources is a good practice to take.

Another key aspect to consider is the use of secure and isolated workstations for sensitive roles. In this official Microsoft document you can get to obtain more details about it.

Segmentation and adoption of the Zero Trust model

The security model, definedZero trust and in contrast with the conventional models based on perimeter security, involves adopting an approach to micro-segmentation and the definition of granular perimeters in your network architecture. To contain security risks, it is good to adopt a clear and simple segmentation strategy, allowing stakeholders with a clear understanding, to facilitate and monitor effective management. It will also be useful to assign the necessary permissions and appropriate network controls.

In this regard, we report a reference design regarding the Azure administrative model:

Figure 1 – Reference Design – Azure Administration Model

The following illustration shows the typical Hub-Spoke network model, where theHub is a virtual network in Azure that serves as a point of connectivity to the on-premises network andSpoke are virtual networks running the peering with the Hub and can be used to isolate workloads.

Figure 2 – Reference Enterprise Design – Azure Network Security

Adoption of an appropriate "Firewall Strategy"

Adopting a firewall solution in the Azure environment to better protect and segregate network flows is now mandatory.

The choice may involve the adoption of:

  • Microsoft solutions fully integrated into the platform, such as Azure Firewall, flanked by Web App Firewall (WAF) of the Application Gateway, an application load balancer (OSI layer 7) for web traffic, that allows you to govern HTTP and HTTPS applications traffic. The Web Application Firewall Module (WAF) for web publications achieves an application protection, based on OWASP Core Rule sets rules. The WAF protects applications from vulnerabilities and common attacks , such as X-Site Scripting and SQL Injection attacks. These solutions are suitable for most of the scenarios and offer intrinsic high availability and scalability functionality as well as a simple configuration and centralized management.
  • Solutions provided by third-party vendors that are available in the Azure Marketplace. The Network Virtual Appliances (NVAs) are numerous, and can provide advanced features and provide continuity in the user experience compared to solutions already active in the on-premises environment. Typically the configuration of these solutions is more complex and the cost tends to be higher than Microsoft solutions.

Choosing a DDoS Mitigation Solution for critical applications

Very important is the protection of all critical applications from distributed denial-of-service cyberattacks (DDoS – Distributed Denial of Service). These attacks are aimed at deliberately to exhaust the resources of a given system that provides a service to clients, such as a website that is hosted on web servers, to the point that it will no longer be able to provide these services to those who require it in a legitimate way.

In Azure, DDoS protection is available in two different tiers: Basic or Standard.

Figure 3 - Comparison of the features available in different tiers for DDoS Protection

The protectionBasic is enabled by default in the Azure platform, which constantly monitors the traffic and enforces real-time mitigation of the most common network attacks. This tier provides the same level of protection adopted and tested by Microsoft online services and operates for the public IP addresses of Azure (IPv4 and IPv6). No configuration is required for the Basic tier.

The Azure DDoS ProtectionStandard provides additional mitigation capabilities compared to Basic tier, which are optimized specifically for the resources in Azure virtual network. Security policies are auto-configured and are optimized by a specific network traffic monitoring and by applying machine learning algorithms, that allow you to profile in the most appropriate and flexible way your application studying the traffic generated. In the moment in which the thresholds set in the policy of DDoS are exceeded, DDoS mitigation process is automatically started, and it is suspended when it falls below the traffic thresholds established. These policies are applied to all public IP of Azure (IPv4) associated with resources present in the virtual network, such as: virtual machines, Azure Load Balancer, Azure Application Gateway, Azure Firewall, VPN Gateway and Azure Service Fabric instances.

Azure Security Center Adoption

Azure Security Center is a cloud solution that helps prevent, detect and respond to security threats that affect the resources and workloads on hybrid environments. To improve the security posture of your Azure environment is essential to assess the adoption of this solution, it is offered in two different tiers:

  • Free tier. In this tier Azure Security Center is totally free and it will do a continuously assessment, providing recommendations concerning the Azure security environment.
  • Standard tier. Compared to tier free adds enhanced threat detection, using behavioral analysis and machine learning to identify zero-day attacks and exploits. Through machine learning techniques and through the creation of whitelist is possible to control the execution of applications to reduce exposure to network attacks and malware. In addition, the standard level adds the ability to perform in an integrated manner a Vulnerability Assessment for virtual machines in Azure. Azure Security Center Standard supports several resources including: VMs, Virtual machine scale sets, App Service, SQL servers, and Storage accounts.

Figure 4 - Comparison between the tiers of Azure Security Center

Azure Security Center assigns a score to your environment, useful for monitoring the risk profile and for try to constantly improve the security postures, applying remediation actions. Good rule is to verify on a regular basis (least monthly) the security score provided by Azure Security Center and program initiatives aimed at improving specific areas. In addition, it is recommended to carefully check the alert that Security Center Standard generates when it detects potential security threats on its resources. Security Center sets priorities, lists the alerts, provides the information needed to quickly examine the problems and provides advice on how to resolve any attacks.

Introduce security in development and release stages

The adoption of DevOps models to deploy Azure applications and services enable, as well as providing maximum agility, to obtain benefits in terms of security. In DevOps models can be engaged in development and management stages the teams dedicated to quality control and security throughout the application lifecycle. Using Infrastructure-as-Code processes(IaC) it is possible to define and monitor the compliance on a large scale.

Do not use legacy technologies

In Azure environment it is not recommended the adoption of classical Network Intrusion Detection System (NIDS) and Network Intrusion Prevention Systems (NIPS) since the platform is able to filter out malformed packets natively. The solutions NIDS / NIPS are generally based on outdated signature-based approaches that can be easily removed during attempted attacks and generally produce a high false positive rate.

Conclusions

Achieve a high level of security in Azure environments is a major challenge that needs to be won and it requires constant monitoring, review and updating of security postures. This article have been reported those that are considered the main best practices of security offered by a direct field experience, which it is always good to enrich them by taking further precautions.