Power Automate - Unusual bulk deletion of flow resources

// minThreshold: Minimum number of apps to be deleted to be considered an anomaly;
// This is to prevent one-off isolated delete flow to be considered outlier.
// The Min Threshold can be reduced or increased according to the traffic in the organization.
let minThreshold=10;
let interval = 1h;
let startTime = ago(14d);
let endTime = now();
let query_frequency = 1h;
let flow_deletion_events = PowerAutomateActivity
    | where TimeGenerated >= startTime
    | where EventOriginalType =~ "DeleteFlow"
    | extend IngestionTimeGenerated = TimeGenerated;
flow_deletion_events
| make-series DeletedFlowCount=count() on IngestionTimeGenerated from startTime to endTime step interval by ActorName, UserUpn, ActorUserId
| extend(Anomalies, AnomalyScore, ExpectedUsage) = series_decompose_anomalies(DeletedFlowCount)
| mv-expand
    DeletedFlowCount to typeof(double),
    IngestionTimeGenerated to typeof(datetime),
    Anomalies to typeof(double),
    AnomalyScore to typeof(double),
    ExpectedUsage to typeof(long)
| where IngestionTimeGenerated >= ago(query_frequency)
| where Anomalies != 0 and DeletedFlowCount >= minThreshold
| lookup (flow_deletion_events
    | where IngestionTimeGenerated >= ago(query_frequency))
    on ActorName, UserUpn, ActorUserId
| extend
    AccountName = tostring(split(ActorName, "@")[0]),
    UPNSuffix = tostring(split(ActorName, "@")[1]),
    PowerAutomateAppId = 27592
| project
    TimeGenerated,
    ActorName,
    DeletedFlowCount,
    ExpectedUsage,
    Anomalies,
    AnomalyScore,
    AccountName,
    UPNSuffix,
    PowerAutomateAppId,
    UserUpn,
    ActorUserId

entityMappings:
- entityType: Account
  fieldMappings:
  - identifier: Name
    columnName: AccountName
  - identifier: UPNSuffix
    columnName: UPNSuffix
- entityType: CloudApplication
  fieldMappings:
  - identifier: AppId
    columnName: PowerAutomateAppId
queryFrequency: 1h
name: Power Automate - Unusual bulk deletion of flow resources
alertDetailsOverride:
  alertDisplayNameFormat: Power Automate - unusual bulk deletion of {{DeletedFlowCount}} flows
  alertDescriptionFormat: User {{ActorName}}  deleted {{DeletedFlowCount}} flows in the last hour, surpassing the bulk delete threshold. This is anomalous compared to the past 14 days.
kind: Scheduled
tactics:
- Impact
- DefenseEvasion
triggerThreshold: 0
query: |
  // minThreshold: Minimum number of apps to be deleted to be considered an anomaly;
  // This is to prevent one-off isolated delete flow to be considered outlier.
  // The Min Threshold can be reduced or increased according to the traffic in the organization.
  let minThreshold=10;
  let interval = 1h;
  let startTime = ago(14d);
  let endTime = now();
  let query_frequency = 1h;
  let flow_deletion_events = PowerAutomateActivity
      | where TimeGenerated >= startTime
      | where EventOriginalType =~ "DeleteFlow"
      | extend IngestionTimeGenerated = TimeGenerated;
  flow_deletion_events
  | make-series DeletedFlowCount=count() on IngestionTimeGenerated from startTime to endTime step interval by ActorName, UserUpn, ActorUserId
  | extend(Anomalies, AnomalyScore, ExpectedUsage) = series_decompose_anomalies(DeletedFlowCount)
  | mv-expand
      DeletedFlowCount to typeof(double),
      IngestionTimeGenerated to typeof(datetime),
      Anomalies to typeof(double),
      AnomalyScore to typeof(double),
      ExpectedUsage to typeof(long)
  | where IngestionTimeGenerated >= ago(query_frequency)
  | where Anomalies != 0 and DeletedFlowCount >= minThreshold
  | lookup (flow_deletion_events
      | where IngestionTimeGenerated >= ago(query_frequency))
      on ActorName, UserUpn, ActorUserId
  | extend
      AccountName = tostring(split(ActorName, "@")[0]),
      UPNSuffix = tostring(split(ActorName, "@")[1]),
      PowerAutomateAppId = 27592
  | project
      TimeGenerated,
      ActorName,
      DeletedFlowCount,
      ExpectedUsage,
      Anomalies,
      AnomalyScore,
      AccountName,
      UPNSuffix,
      PowerAutomateAppId,
      UserUpn,
      ActorUserId  
relevantTechniques:
- T1485
- T0828
- T1562
triggerOperator: gt
customDetails:
  DeletedFlowCount: DeletedFlowCount
queryPeriod: 14d
eventGroupingSettings:
  aggregationKind: SingleAlert
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Business Applications/Analytic Rules/Power Automate - Unusual bulk deletion of flow resources.yaml
severity: Medium
status: Available
id: 56cb646e-56a0-4f0e-8866-9bc1dd15da78
requiredDataConnectors:
- connectorId: PowerAutomate
  dataTypes:
  - PowerAutomateActivity
version: 3.2.0
description: Identifies bulk deletion of Power Automate flows that exceed a predefined threshold defined in the query and deviate from activity patterns observed in the last 14 days.

{
  "$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/56cb646e-56a0-4f0e-8866-9bc1dd15da78')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/56cb646e-56a0-4f0e-8866-9bc1dd15da78')]",
      "properties": {
        "alertDetailsOverride": {
          "alertDescriptionFormat": "User {{ActorName}}  deleted {{DeletedFlowCount}} flows in the last hour, surpassing the bulk delete threshold. This is anomalous compared to the past 14 days.",
          "alertDisplayNameFormat": "Power Automate - unusual bulk deletion of {{DeletedFlowCount}} flows"
        },
        "alertRuleTemplateName": "56cb646e-56a0-4f0e-8866-9bc1dd15da78",
        "customDetails": {
          "DeletedFlowCount": "DeletedFlowCount"
        },
        "description": "Identifies bulk deletion of Power Automate flows that exceed a predefined threshold defined in the query and deviate from activity patterns observed in the last 14 days.",
        "displayName": "Power Automate - Unusual bulk deletion of flow resources",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "AccountName",
                "identifier": "Name"
              },
              {
                "columnName": "UPNSuffix",
                "identifier": "UPNSuffix"
              }
            ]
          },
          {
            "entityType": "CloudApplication",
            "fieldMappings": [
              {
                "columnName": "PowerAutomateAppId",
                "identifier": "AppId"
              }
            ]
          }
        ],
        "eventGroupingSettings": {
          "aggregationKind": "SingleAlert"
        },
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Business Applications/Analytic Rules/Power Automate - Unusual bulk deletion of flow resources.yaml",
        "query": "// minThreshold: Minimum number of apps to be deleted to be considered an anomaly;\n// This is to prevent one-off isolated delete flow to be considered outlier.\n// The Min Threshold can be reduced or increased according to the traffic in the organization.\nlet minThreshold=10;\nlet interval = 1h;\nlet startTime = ago(14d);\nlet endTime = now();\nlet query_frequency = 1h;\nlet flow_deletion_events = PowerAutomateActivity\n    | where TimeGenerated >= startTime\n    | where EventOriginalType =~ \"DeleteFlow\"\n    | extend IngestionTimeGenerated = TimeGenerated;\nflow_deletion_events\n| make-series DeletedFlowCount=count() on IngestionTimeGenerated from startTime to endTime step interval by ActorName, UserUpn, ActorUserId\n| extend(Anomalies, AnomalyScore, ExpectedUsage) = series_decompose_anomalies(DeletedFlowCount)\n| mv-expand\n    DeletedFlowCount to typeof(double),\n    IngestionTimeGenerated to typeof(datetime),\n    Anomalies to typeof(double),\n    AnomalyScore to typeof(double),\n    ExpectedUsage to typeof(long)\n| where IngestionTimeGenerated >= ago(query_frequency)\n| where Anomalies != 0 and DeletedFlowCount >= minThreshold\n| lookup (flow_deletion_events\n    | where IngestionTimeGenerated >= ago(query_frequency))\n    on ActorName, UserUpn, ActorUserId\n| extend\n    AccountName = tostring(split(ActorName, \"@\")[0]),\n    UPNSuffix = tostring(split(ActorName, \"@\")[1]),\n    PowerAutomateAppId = 27592\n| project\n    TimeGenerated,\n    ActorName,\n    DeletedFlowCount,\n    ExpectedUsage,\n    Anomalies,\n    AnomalyScore,\n    AccountName,\n    UPNSuffix,\n    PowerAutomateAppId,\n    UserUpn,\n    ActorUserId\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "P14D",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "DefenseEvasion",
          "Impact"
        ],
        "techniques": [
          "T1485",
          "T1562"
        ],
        "templateVersion": "3.2.0",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}