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

entityMappings:
- entityType: Account
  fieldMappings:
  - identifier: Name
    columnName: accountName
  - identifier: UPNSuffix
    columnName: upnSuffix
name: Conditional Access - Dynamic Group Exclusion Changes
queryFrequency: 5m
triggerOperator: gt
suppressionEnabled: false
suppressionDuration: 5h
queryPeriod: 5m
requiredDataConnectors:
- connectorId: AzureActiveDirectory
  dataTypes:
  - AuditLogs
tactics:
- PrivilegeEscalation
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
description: // Detects changes to Dynamic Membership Rules for specified groups (often used in CA exclusions)
severity: High
incidentConfiguration:
  groupingConfiguration:
    lookbackDuration: PT5H
    groupByCustomDetails: []
    groupByEntities: []
    enabled: false
    groupByAlertDetails: []
    matchingMethod: AllEntities
    reopenClosedIncident: false
  createIncident: true
kind: Scheduled
eventGroupingSettings:
  aggregationKind: AlertPerResult
triggerThreshold: 0
id: c385944b-17b9-4b2b-921e-0e8d0341a675
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft%20Entra%20ID/Analytic%20Rules/Conditional%20Access%20-%20Dynamic%20Group%20Exclusion%20Changes.yaml
version: 1.0.1
relevantTechniques:
- T1484

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2024-01-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/c385944b-17b9-4b2b-921e-0e8d0341a675')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/c385944b-17b9-4b2b-921e-0e8d0341a675')]",
      "properties": {
        "alertRuleTemplateName": "c385944b-17b9-4b2b-921e-0e8d0341a675",
        "customDetails": null,
        "description": "// Detects changes to Dynamic Membership Rules for specified groups (often used in CA exclusions)",
        "displayName": "Conditional Access - Dynamic Group Exclusion Changes",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "accountName",
                "identifier": "Name"
              },
              {
                "columnName": "upnSuffix",
                "identifier": "UPNSuffix"
              }
            ]
          }
        ],
        "eventGroupingSettings": {
          "aggregationKind": "AlertPerResult"
        },
        "incidentConfiguration": {
          "createIncident": true,
          "groupingConfiguration": {
            "enabled": false,
            "groupByAlertDetails": [],
            "groupByCustomDetails": [],
            "groupByEntities": [],
            "lookbackDuration": "PT5H",
            "matchingMethod": "AllEntities",
            "reopenClosedIncident": false
          }
        },
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft%20Entra%20ID/Analytic%20Rules/Conditional%20Access%20-%20Dynamic%20Group%20Exclusion%20Changes.yaml",
        "query": "// Detects changes to Dynamic Membership Rules for specified groups (often used in CA exclusions)\nlet monitoredGroups = dynamic([\"Group1\", \"Group2\"]);  // <-- Customize this list\nAuditLogs\n| where OperationName == \"Update group\"\n| where AdditionalDetails[0].value == \"DynamicMembership\"\n| extend DynamicGroupName = tostring(TargetResources[0].displayName)\n| where DynamicGroupName in (monitoredGroups)\n| extend modifiedBy = tostring(InitiatedBy.user.userPrincipalName)\n| extend accountName = tostring(split(modifiedBy, \"@\")[0])\n| extend upnSuffix = tostring(split(modifiedBy, \"@\")[1])\n| extend oldRule = tostring(TargetResources[0].modifiedProperties[0].oldValue)\n| extend newRule = tostring(TargetResources[0].modifiedProperties[0].newValue)\n| where oldRule != newRule\n| project\n    TimeGenerated,\n    OperationName,\n    DynamicGroupName,\n    modifiedBy,\n    accountName,\n    upnSuffix,\n    result = Result,\n    oldRule,\n    newRule\n| order by TimeGenerated desc",
        "queryFrequency": "PT5M",
        "queryPeriod": "PT5M",
        "severity": "High",
        "subTechniques": [],
        "suppressionDuration": "PT5H",
        "suppressionEnabled": false,
        "tactics": [
          "PrivilegeEscalation"
        ],
        "techniques": [
          "T1484"
        ],
        "templateVersion": "1.0.1",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}