Cisco SEG - Multiple large emails sent to external recipient

let e_theshold = 3;
let s_threshold = 10000000;
CiscoSEGEvent
| where AdditionalFields[15]['ESAMsgSize'] > s_threshold
| where NetworkDirection =~ 'Outgoing'
| extend rec_domain = extract(@'@(.*)', 1, DstUserName)
| extend s_domain = extract(@'@(.*)', 1, SrcUserName)
| where s_domain != rec_domain
| summarize count() by SrcUserName
| where count_ >= e_theshold
| extend AccountCustomEntity = SrcUserName

relevantTechniques:
- T1030
name: Cisco SEG - Multiple large emails sent to external recipient
requiredDataConnectors:
- dataTypes:
  - CommonSecurityLog
  connectorId: CefAma
entityMappings:
- fieldMappings:
  - identifier: Name
    columnName: AccountCustomEntity
  entityType: Account
triggerThreshold: 0
id: 1399a9a5-6200-411e-8c34-ca5658754cf7
tactics:
- Exfiltration
version: 1.0.3
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/CiscoSEG/Analytic Rules/CiscoSEGMultipleLargeEmails.yaml
queryPeriod: 1h
kind: Scheduled
queryFrequency: 1h
severity: Medium
status: Available
description: |
    'Detects possible data exfiltration.'
query: |
  let e_theshold = 3;
  let s_threshold = 10000000;
  CiscoSEGEvent
  | where AdditionalFields[15]['ESAMsgSize'] > s_threshold
  | where NetworkDirection =~ 'Outgoing'
  | extend rec_domain = extract(@'@(.*)', 1, DstUserName)
  | extend s_domain = extract(@'@(.*)', 1, SrcUserName)
  | where s_domain != rec_domain
  | summarize count() by SrcUserName
  | where count_ >= e_theshold
  | extend AccountCustomEntity = SrcUserName  
triggerOperator: gt

{
  "$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/1399a9a5-6200-411e-8c34-ca5658754cf7')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/1399a9a5-6200-411e-8c34-ca5658754cf7')]",
      "properties": {
        "alertRuleTemplateName": "1399a9a5-6200-411e-8c34-ca5658754cf7",
        "customDetails": null,
        "description": "'Detects possible data exfiltration.'\n",
        "displayName": "Cisco SEG - Multiple large emails sent to external recipient",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "AccountCustomEntity",
                "identifier": "Name"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/CiscoSEG/Analytic Rules/CiscoSEGMultipleLargeEmails.yaml",
        "query": "let e_theshold = 3;\nlet s_threshold = 10000000;\nCiscoSEGEvent\n| where AdditionalFields[15]['ESAMsgSize'] > s_threshold\n| where NetworkDirection =~ 'Outgoing'\n| extend rec_domain = extract(@'@(.*)', 1, DstUserName)\n| extend s_domain = extract(@'@(.*)', 1, SrcUserName)\n| where s_domain != rec_domain\n| summarize count() by SrcUserName\n| where count_ >= e_theshold\n| extend AccountCustomEntity = SrcUserName\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Exfiltration"
        ],
        "techniques": [
          "T1030"
        ],
        "templateVersion": "1.0.3",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}