Dataverse - Guest user exfiltration following Power Platform defense impairment

id: 39efbf4b-b347-4cc7-895e-99a868bf29ea
kind: Scheduled
name: Dataverse - Guest user exfiltration following Power Platform defense impairment
description: |
  Identifies a chain of events starting with disablement of Power Platform tenant isolation and removal of an environment's access security group. These events are correlated with Dataverse exfiltration alerts associated with the impacted environment and recently created Microsoft Entra guest users.

  Note: Activate other Dataverse analytics rules with the MITRE tactic 'Exfiltration' before enabling this rule.
severity: High
status: Available
requiredDataConnectors:
  - connectorId: PowerPlatformAdmin
    dataTypes:
      - PowerPlatformAdminActivity
  - connectorId: AzureActiveDirectory
    dataTypes:
      - AuditLogs
  - connectorId: AzureActiveDirectoryIdentityProtection
    dataTypes:
      - SecurityAlert
queryFrequency: 1h
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - DefenseEvasion
  - Exfiltration
relevantTechniques:
  - T1629
  - T1567
query: |
  let query_lookback = 14d;
  let query_frequncy = 1h;
  let defense_evasion_events = PowerPlatformAdminActivity
      | where TimeGenerated >= ago(query_lookback)
      | where EventOriginalType == "TenantIsolationOperation"
      | mv-expand PropertyCollection
      | where PropertyCollection.Name == "powerplatform.analytics.resource.tenant.isolation_policy.enabled"
      | where PropertyCollection.Value == "False"
      | summarize
          TenantIsolationRemovalTimestamp = max(TimeGenerated)
          by SecurityDisablingUser = ActorName
      | join kind=inner (
          PowerPlatformAdminActivity
          | where TimeGenerated >= ago(query_lookback)
          | where EventOriginalType == "EnvironmentPropertyChange"
          | where PropertyCollection has "Property: SecurityGroupId, Old Value: , New Value: "
          | mv-expand PropertyCollection
          | extend
              GroupRemovalTimestamp = TimeGenerated,
              InstanceUrl = tostring(iif(PropertyCollection.Name == "powerplatform.analytics.resource.environment.url", PropertyCollection.Value, "")),
              EnvironmentId = tostring(iif(PropertyCollection.Name == "powerplatform.analytics.resource.environment.name", PropertyCollection.Value, ""))
          | summarize InstanceUrl = max(InstanceUrl), EnvironmentId = max(EnvironmentId) by GroupRemovalTimestamp, SecurityDisablingUser = ActorName)
          on SecurityDisablingUser
      | summarize
          GroupRemovalTimestamp = max(GroupRemovalTimestamp),
          TenantIsolationRemovalTimestamp = max(TenantIsolationRemovalTimestamp)
          by SecurityDisablingUser, InstanceUrl, EnvironmentId;
  let exfiltration_alerts = SecurityAlert
      | where TimeGenerated >= ago(query_frequncy)
      | where Tactics has "Exfiltration"
      | where Entities has ('"AppId":32780')
      | mv-expand todynamic(Entities)
      | extend AlertUPN = iif(Entities.Type == "account", strcat(Entities.Name, "@", Entities.UPNSuffix), "")
      | extend InstanceUrl = tostring(iif(Entities.AppId == 32780, Entities.InstanceName, ""))
      | join kind=inner defense_evasion_events on InstanceUrl
      | where StartTime > TenantIsolationRemovalTimestamp and StartTime > GroupRemovalTimestamp
      | summarize InstanceUrl = max(InstanceUrl), AlertUPN = max(AlertUPN) by AlertName, SystemAlertId
      | extend AlertDetails = bag_pack("AlertName", AlertName, "SystemAlertId", SystemAlertId)
      | summarize AlertDetails = make_set(AlertDetails, 100) by AlertUPN, InstanceUrl
      | join kind=inner (
          AuditLogs
          | where OperationName == "Update user"
          | where Identity == "Microsoft Invitation Acceptance Portal"
          | mv-expand TargetResources
          | extend ModifiedProperties = TargetResources.modifiedProperties
          | mv-expand ModifiedProperties
          | where ModifiedProperties.displayName == "AcceptedAs"
          | summarize RedeemTime = max(TimeGenerated) by GuestUser = tostring(parse_json(replace_regex(tostring(ModifiedProperties.newValue), "\\r", ""))[0]))
          on $left.AlertUPN == $right.GuestUser;
  defense_evasion_events
  | join kind=inner exfiltration_alerts on InstanceUrl
  | extend
      AccountName = tostring(split(SecurityDisablingUser, "@")[0]),
      UPNSuffix = tostring(split(SecurityDisablingUser, "@")[1]),
      GuestAccountName = tostring(split(GuestUser, "@")[0]),
      GuestUPNSuffix = tostring(split(GuestUser, "@")[0]),
      DataverseId = 32780
  | project
      SecurityDisablingUser,
      GuestUser,
      AlertDetails,
      TenantIsolationRemovalTimestamp,
      GroupRemovalTimestamp,
      InstanceUrl,
      EnvironmentId,
      AccountName,
      UPNSuffix,
      GuestAccountName,
      GuestUPNSuffix,
      DataverseId
eventGroupingSettings:
  aggregationKind: SingleAlert
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: AccountName
      - identifier: UPNSuffix
        columnName: UPNSuffix
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: GuestAccountName
      - identifier: UPNSuffix
        columnName: GuestUPNSuffix
  - entityType: CloudApplication
    fieldMappings:
      - identifier: AppId
        columnName: DataverseId
      - identifier: InstanceName
        columnName: InstanceUrl
alertDetailsOverride:
  alertDisplayNameFormat: 'Dataverse - exfiltration alerts following defense impairment
    in {{InstanceUrl}} '
  alertDescriptionFormat: '{{SecurityDisablingUser}} disabled Power Platform tenant
    isolation and removed the security group used to control access to {{{InstanceUrl}}.
    Exfiltration alerts associated with guest users were then detected from user {{{GuestUser}}'
customDetails:
  Environment: EnvironmentId
version: 3.2.0