Design Planning (Part 1)

By Ashwin Venugopal -

 



To read part 2, please click here
To read part 3, please click here



Data Residency Requirements

According to the type of business and customer residency, organizations might have compliance restrictions related to the logged data. These compliance regulations may not be defined clearly with respect to logging requirements and subject to change with time. Hence, organizations may choose local region to avoid complications.

The selection of a region also carries implications for Microsoft Sentinel and Log Analytics costs as well as the availability of resources for the specific region. Regions like the U.S. can offer a significant cost advantage in comparison to other regions. The discount can be significant depending upon the volume of log ingestion. Therefore, the project team should obtain organizational requirements related to data residency before deploying.

Number of Azure AD Tenants

An Azure AD tenant offers Identity and Access Management (IAM) capabilities for applications and resources used within an organization. Most of the organizations have single Azure AD tenant, but some might have more than one due to mergers and acquisitions or they might need to segregate environments such as corporate versus production infrastructure. 

Each Azure tenant requires a separate Microsoft Sentinel instance because some of the data connectors may only work within the current Azure tenant. So, solutions based on custom connectors and Azure REST APIs can be developed to aggregate remote tenant logs into a single Microsoft Sentinel instance. However, these solutions might create an unnecessary level of complexity and increased maintenance that should be avoided unless otherwise. Azure Lighthouse can provide cross-tenant management experience for unified platform tooling, management at scale, and increased visibility. 

Number of Azure Subscriptions

A single Microsoft Sentinel instance can integrate data from multiple Azure subscriptions. But some security or operational solutions may have restrictions on their logging capabilities that limits the sending of logging/diagnostics data to different subscriptions. Such solutions requires a custom connector that can be configured with the help of many methods. 

Microsoft Sentinel can be deployed in existing subscriptions or in its own subscription without any implications for its functionality. A dedicated subscription is recommended in following situations:

  • There is a need to clearly identify or segregate any costs associated with Microsoft Sentinel. 

  • Permissions needed to be assigned at the subscription level to allow the creation and management of various resources required for a full Microsoft Sentinel configuration. However, for complex environment this cloud be VMs, function apps, automation accounts, storage accounts, data explorer clusters, key vaults, machine learning, and databases. 
If Microsoft Sentinel is deployed in multiple subscriptions, access can be managed centrally through regular assignment of Azure AD roles. Azure Lighthouse is not required here because it is designed to offer cross-tenant access. 

Conclusion

Here are the key factors that can affect the initial architecture for deployments of new Microsoft Sentinel instances or the migration from existing SIEM platforms. 




To read part 2, please click here
To read part 3, please click here












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