Conditional Access - Dynamic Group Exclusion Changes

// Detects changes to Dynamic Membership Rules for specified groups (often used in CA exclusions)
let monitoredGroups = dynamic(["Group1", "Group2"]);  // <-- Customize this list
AuditLogs
| where OperationName == "Update group"
| where AdditionalDetails[0].value == "DynamicMembership"
| extend DynamicGroupName = tostring(TargetResources[0].displayName)
| where DynamicGroupName in (monitoredGroups)
| extend modifiedBy = tostring(InitiatedBy.user.userPrincipalName)
| extend accountName = tostring(split(modifiedBy, "@")[0])
| extend upnSuffix = tostring(split(modifiedBy, "@")[1])
| extend oldRule = tostring(TargetResources[0].modifiedProperties[0].oldValue)
| extend newRule = tostring(TargetResources[0].modifiedProperties[0].newValue)
| where oldRule != newRule
| project
    TimeGenerated,
    OperationName,
    DynamicGroupName,
    modifiedBy,
    accountName,
    upnSuffix,
    result = Result,
    oldRule,
    newRule
| order by TimeGenerated desc

suppressionEnabled: false
description: // Detects changes to Dynamic Membership Rules for specified groups (often used in CA exclusions)
kind: Scheduled
tactics:
- PrivilegeEscalation
requiredDataConnectors:
- connectorId: AzureActiveDirectory
  dataTypes:
  - AuditLogs
incidentConfiguration:
  groupingConfiguration:
    enabled: false
    groupByEntities: []
    reopenClosedIncident: false
    lookbackDuration: PT5H
    matchingMethod: AllEntities
    groupByCustomDetails: []
    groupByAlertDetails: []
  createIncident: true
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Entra ID/Analytic Rules/Conditional Access - Dynamic Group Exclusion Changes.yaml
severity: High
name: Conditional Access - Dynamic Group Exclusion Changes
suppressionDuration: 5h
eventGroupingSettings:
  aggregationKind: AlertPerResult
triggerThreshold: 0
queryPeriod: 5m
query: |-
  // Detects changes to Dynamic Membership Rules for specified groups (often used in CA exclusions)
  let monitoredGroups = dynamic(["Group1", "Group2"]);  // <-- Customize this list
  AuditLogs
  | where OperationName == "Update group"
  | where AdditionalDetails[0].value == "DynamicMembership"
  | extend DynamicGroupName = tostring(TargetResources[0].displayName)
  | where DynamicGroupName in (monitoredGroups)
  | extend modifiedBy = tostring(InitiatedBy.user.userPrincipalName)
  | extend accountName = tostring(split(modifiedBy, "@")[0])
  | extend upnSuffix = tostring(split(modifiedBy, "@")[1])
  | extend oldRule = tostring(TargetResources[0].modifiedProperties[0].oldValue)
  | extend newRule = tostring(TargetResources[0].modifiedProperties[0].newValue)
  | where oldRule != newRule
  | project
      TimeGenerated,
      OperationName,
      DynamicGroupName,
      modifiedBy,
      accountName,
      upnSuffix,
      result = Result,
      oldRule,
      newRule
  | order by TimeGenerated desc  
relevantTechniques:
- T1484
id: c385944b-17b9-4b2b-921e-0e8d0341a675
queryFrequency: 5m
entityMappings:
- entityType: Account
  fieldMappings:
  - columnName: accountName
    identifier: Name
  - columnName: upnSuffix
    identifier: UPNSuffix
triggerOperator: gt
version: 1.0.1