Common Event Format CEF via AMA - Critical or High Severity Detections by User

let timeframe = 1h;
let threshold = 15; // update threshold value based on organization's preference
let NotableEvents = CrowdStrikeFalconEventStream
| where TimeGenerated > ago(timeframe)
| where EventType == "DetectionSummaryEvent"
| where Severity in ("Critical", "High")
| summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), Total = count() by DstUserName, DstHostName, SrcIpAddr, FileName, FileHash, Message
| where Total > threshold;
NotableEvents
| extend timestamp = StartTimeUtc, AccountCustomEntity = DstUserName, HostCustomEntity = DstHostName, IPCustomEntity = SrcIpAddr, FileHashCustomEntity = FileHash, FileHashAlgo = "MD5"
| project timestamp, StartTimeUtc, EndTimeUtc, DstUserName, DstHostName, SrcIpAddr, FileName, FileHash, FileHashAlgo, Message, Total, AccountCustomEntity, HostCustomEntity, IPCustomEntity, FileHashCustomEntity

version: 1.0.6
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/CrowdStrike%20Falcon%20Endpoint%20Protection/Analytic%20Rules/CriticalOrHighSeverityDetectionsByUser.yaml
triggerThreshold: 0
requiredDataConnectors:
- dataTypes:
  - CommonSecurityLog
  connectorId: CefAma
tactics:
- Impact
- DefenseEvasion
relevantTechniques:
- T1489
- T1562
kind: Scheduled
alertDetailsOverride:
  alertDescriptionFormat: User {{DstUserName}} generated {{Total}} critical/high detections from host {{DstHostName}}.
  alertDisplayNameFormat: 'CrowdStrike critical/high detections by user: {{DstUserName}}'
entityMappings:
- fieldMappings:
  - identifier: FullName
    columnName: AccountCustomEntity
  entityType: Account
- fieldMappings:
  - identifier: FullName
    columnName: HostCustomEntity
  entityType: Host
- fieldMappings:
  - identifier: Address
    columnName: IPCustomEntity
  entityType: IP
- fieldMappings:
  - identifier: Algorithm
    columnName: FileHashAlgo
  - identifier: Value
    columnName: FileHashCustomEntity
  entityType: FileHash
description: |
  'Creates an incident when a large number of Critical or High severity CrowdStrike Falcon sensor detections is triggered by a single user within 1 hour. The rule uses the CrowdStrikeFalconEventStream table, filters for DetectionSummaryEvent records with Severity set to Critical or High, and alerts when detections for a single DstUserName exceed the configured threshold of 15. Review DstHostName, SrcIpAddr, FileName, FileHash, and Message for investigation context.'
triggerOperator: gt
status: Available
queryFrequency: 1h
id: 4465ebde-b381-45f7-ad08-7d818070a11c
name: Common Event Format (CEF) via AMA - Critical or High Severity Detections by User
severity: High
query: |
  let timeframe = 1h;
  let threshold = 15; // update threshold value based on organization's preference
  let NotableEvents = CrowdStrikeFalconEventStream
  | where TimeGenerated > ago(timeframe)
  | where EventType == "DetectionSummaryEvent"
  | where Severity in ("Critical", "High")
  | summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), Total = count() by DstUserName, DstHostName, SrcIpAddr, FileName, FileHash, Message
  | where Total > threshold;
  NotableEvents
  | extend timestamp = StartTimeUtc, AccountCustomEntity = DstUserName, HostCustomEntity = DstHostName, IPCustomEntity = SrcIpAddr, FileHashCustomEntity = FileHash, FileHashAlgo = "MD5"
  | project timestamp, StartTimeUtc, EndTimeUtc, DstUserName, DstHostName, SrcIpAddr, FileName, FileHash, FileHashAlgo, Message, Total, AccountCustomEntity, HostCustomEntity, IPCustomEntity, FileHashCustomEntity
queryPeriod: 1h
customDetails:
  FileHash: FileHash
  Total: Total
  SrcIpAddr: SrcIpAddr
  DstUserName: DstUserName
  FileName: FileName
  DstHostName: DstHostName

{
  "$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/4465ebde-b381-45f7-ad08-7d818070a11c')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/4465ebde-b381-45f7-ad08-7d818070a11c')]",
      "properties": {
        "alertDetailsOverride": {
          "alertDescriptionFormat": "User {{DstUserName}} generated {{Total}} critical/high detections from host {{DstHostName}}.",
          "alertDisplayNameFormat": "CrowdStrike critical/high detections by user: {{DstUserName}}"
        },
        "alertRuleTemplateName": "4465ebde-b381-45f7-ad08-7d818070a11c",
        "customDetails": {
          "DstHostName": "DstHostName",
          "DstUserName": "DstUserName",
          "FileHash": "FileHash",
          "FileName": "FileName",
          "SrcIpAddr": "SrcIpAddr",
          "Total": "Total"
        },
        "description": "'Creates an incident when a large number of Critical or High severity CrowdStrike Falcon sensor detections is triggered by a single user within 1 hour. The rule uses the CrowdStrikeFalconEventStream table, filters for DetectionSummaryEvent records with Severity set to Critical or High, and alerts when detections for a single DstUserName exceed the configured threshold of 15. Review DstHostName, SrcIpAddr, FileName, FileHash, and Message for investigation context.'\n",
        "displayName": "Common Event Format (CEF) via AMA - Critical or High Severity Detections by User",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "AccountCustomEntity",
                "identifier": "FullName"
              }
            ]
          },
          {
            "entityType": "Host",
            "fieldMappings": [
              {
                "columnName": "HostCustomEntity",
                "identifier": "FullName"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "IPCustomEntity",
                "identifier": "Address"
              }
            ]
          },
          {
            "entityType": "FileHash",
            "fieldMappings": [
              {
                "columnName": "FileHashAlgo",
                "identifier": "Algorithm"
              },
              {
                "columnName": "FileHashCustomEntity",
                "identifier": "Value"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/CrowdStrike%20Falcon%20Endpoint%20Protection/Analytic%20Rules/CriticalOrHighSeverityDetectionsByUser.yaml",
        "query": "let timeframe = 1h;\nlet threshold = 15; // update threshold value based on organization's preference\nlet NotableEvents = CrowdStrikeFalconEventStream\n| where TimeGenerated > ago(timeframe)\n| where EventType == \"DetectionSummaryEvent\"\n| where Severity in (\"Critical\", \"High\")\n| summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), Total = count() by DstUserName, DstHostName, SrcIpAddr, FileName, FileHash, Message\n| where Total > threshold;\nNotableEvents\n| extend timestamp = StartTimeUtc, AccountCustomEntity = DstUserName, HostCustomEntity = DstHostName, IPCustomEntity = SrcIpAddr, FileHashCustomEntity = FileHash, FileHashAlgo = \"MD5\"\n| project timestamp, StartTimeUtc, EndTimeUtc, DstUserName, DstHostName, SrcIpAddr, FileName, FileHash, FileHashAlgo, Message, Total, AccountCustomEntity, HostCustomEntity, IPCustomEntity, FileHashCustomEntity\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "High",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "DefenseEvasion",
          "Impact"
        ],
        "techniques": [
          "T1489",
          "T1562"
        ],
        "templateVersion": "1.0.6",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}