Critical or High Severity Detections by User

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Id	4465ebde-b381-45f7-ad08-7d818070a11c
Rulename	Critical or High Severity Detections by User
Description	Creates an incident when a large number of Critical/High severity CrowdStrike Falcon sensor detections is triggered by a single user
Severity	High
Required data connectors	CefAma
Kind	Scheduled
Query frequency	1h
Query period	1h
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/CrowdStrike Falcon Endpoint Protection/Analytic Rules/CriticalOrHighSeverityDetectionsByUser.yaml
Version	1.0.4
Arm template	4465ebde-b381-45f7-ad08-7d818070a11c.json

KQL

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

YAML

queryPeriod: 1h
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
relevantTechniques: []
severity: High
requiredDataConnectors:
- connectorId: CefAma
  dataTypes:
  - CommonSecurityLog
id: 4465ebde-b381-45f7-ad08-7d818070a11c
triggerOperator: gt
kind: Scheduled
query: |
  let timeframe = 1h;
  let threshold = 15; // update threshold value based on organization's preference
  let NoteableEvents = CrowdStrikeFalconEventStream
  | where TimeGenerated > ago(timeframe)
  | where EventType == "DetectionSummaryEvent"
  | where Severity in ("Critical", "High")
  | summarize Total = count() by DstUserName
  | where Total > threshold;
  CrowdStrikeFalconEventStream
  | where TimeGenerated > ago(timeframe)
  | where EventType == "DetectionSummaryEvent"
  | where Severity in ("Critical", "High")
  | join kind=inner (NoteableEvents) on DstUserName
  | summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), Total = count() by DstHostName, SrcIpAddr, DstUserName, FileName, FileHash, Message
  | extend timestamp = StartTimeUtc, AccountCustomEntity = DstUserName, HostCustomEntity = DstHostName, IPCustomEntity = SrcIpAddr, FileHashCustomEntity = FileHash, FileHashAlgo = "MD5"  
tactics: []
triggerThreshold: 0
queryFrequency: 1h
status: Available
description: |
    'Creates an incident when a large number of Critical/High severity CrowdStrike Falcon sensor detections is triggered by a single user'
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/CrowdStrike Falcon Endpoint Protection/Analytic Rules/CriticalOrHighSeverityDetectionsByUser.yaml
name: Critical or High Severity Detections by User
version: 1.0.4

ARM

{
  "$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": {
        "alertRuleTemplateName": "4465ebde-b381-45f7-ad08-7d818070a11c",
        "customDetails": null,
        "description": "'Creates an incident when a large number of Critical/High severity CrowdStrike Falcon sensor detections is triggered by a single user'\n",
        "displayName": "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 Falcon Endpoint Protection/Analytic Rules/CriticalOrHighSeverityDetectionsByUser.yaml",
        "query": "let timeframe = 1h;\nlet threshold = 15; // update threshold value based on organization's preference\nlet NoteableEvents = CrowdStrikeFalconEventStream\n| where TimeGenerated > ago(timeframe)\n| where EventType == \"DetectionSummaryEvent\"\n| where Severity in (\"Critical\", \"High\")\n| summarize Total = count() by DstUserName\n| where Total > threshold;\nCrowdStrikeFalconEventStream\n| where TimeGenerated > ago(timeframe)\n| where EventType == \"DetectionSummaryEvent\"\n| where Severity in (\"Critical\", \"High\")\n| join kind=inner (NoteableEvents) on DstUserName\n| summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), Total = count() by DstHostName, SrcIpAddr, DstUserName, FileName, FileHash, Message\n| extend timestamp = StartTimeUtc, AccountCustomEntity = DstUserName, HostCustomEntity = DstHostName, IPCustomEntity = SrcIpAddr, FileHashCustomEntity = FileHash, FileHashAlgo = \"MD5\"\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "High",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [],
        "techniques": [],
        "templateVersion": "1.0.4",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}