Security policies in Defender for Cloud
Security policies in Microsoft Defender for Cloud consist of security standards and recommendations that help to improve your cloud security posture.
Security standards define rules, compliance conditions for those rules, and actions (effects) to be taken if conditions aren't met. Defender for Cloud assesses resources and workloads against the security standards enabled in your Azure subscriptions, Amazon Web Services (AWS) accounts, and Google Cloud Platform (GCP) projects. Based on those assessments, security recommendations provide practical steps to help you remediate security issues.
Security standards in Defender for Cloud come from these sources:
Microsoft cloud security benchmark (MCSB): The MCSB standard is applied by default when you onboard Defender for Cloud to a management group or subscription. Your secure score is based on assessment against some MCSB recommendations.
Regulatory compliance standards: When you enable one or more Defender for Cloud plans, you can add standards from a wide range of predefined regulatory compliance programs.
Custom standards: You can create custom security standards in Defender for Cloud, and then add built-in and custom recommendations to those custom standards as needed.
Security standards in Defender for Cloud are based on Azure Policy initiatives or on the Defender for Cloud native platform. Currently, Azure standards are based on Azure Policy. AWS and GCP standards are based on Defender for Cloud.
Security standards in Defender for Cloud simplify the complexity of Azure Policy. In most cases, you can work directly with security standards and recommendations in the Defender for Cloud portal, without needing to directly configure Azure Policy.
Working with security standards
Here's what you can do with security standards in Defender for Cloud:
Modify the built-in MCSB for the subscription: When you enable Defender for Cloud, the MCSB is automatically assigned to all Defender for Cloud registered subscriptions.
Add regulatory compliance standards: If you have one or more paid plans enabled, you can assign built-in compliance standards against which to assess your Azure, AWS, and GCP resources. Learn more about assigning regulatory standards.
Add custom standards: If you have at least one paid Defender plan enabled, you can define new Azure standards or AWS/GCP standards in the Defender for Cloud portal. You can then add recommendations to those standards.
Working with custom standards
Custom standards appear alongside built-in standards in the Regulatory compliance dashboard.
Recommendations derived from assessments against custom standards appear together with recommendations from built-in standards. Custom standards can contain built-in and custom recommendations.
Defender for Cloud periodically and continuously analyzes and assesses the security state of protected resources against defined security standards, to identify potential security misconfigurations and weaknesses. Defender for Cloud then provides recommendations based on assessment findings.
Each recommendation provides the following information:
- A short description of the issue
- Remediation steps for implementing the recommendation
- Affected resources
- Risk level
- Risk factors
- Attack paths
Every recommendation in Defender for Cloud has an associated risk level that represents how exploitable and impactful the security issue is in your environment. The risk assessment engine takes into account factors such as internet exposure, sensitivity of data, lateral movement possibilities, and attack path remediation. You can prioritize recommendations based on their risk levels.
Currently, risk prioritization is in public preview and doesn't affect the secure score.
The MCSB standard is an Azure Policy initiative that includes multiple compliance controls. One of these controls is "Storage accounts should restrict network access using virtual network rules."
As Defender for Cloud continually assesses and finds resources that don't satisfy this control, it marks the resources as noncompliant and triggers a recommendation. In this case, guidance is to harden Azure Storage accounts that aren't protected with virtual network rules.
Custom recommendations (Azure)
To create custom recommendations for Azure subscriptions, you currently need to use Azure Policy.
You create a policy definition, assign it to a policy initiative, and merge that initiative and policy into Defender for Cloud. Learn more.
Custom recommendations (AWS or GCP)
To create custom recommendations for AWS or GCP resources, you must have the Defender CSPM plan enabled.
Custom standards act as a logical grouping for custom recommendations. You can assign custom recommendations to one or more custom standards.
In custom recommendations, you specify a unique name, a description, steps for remediation, severity, and which standards the recommendation should be assigned to. You add recommendation logic with Kusto Query Language (KQL). A simple query editor provides a built-in query template that you can tweak as needed, or you can write your KQL query from scratch.