Cisco SEG - Suspicious sender domain

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Id	ef0a253c-95b5-48e1-8ebc-dbeb073b9338
Rulename	Cisco SEG - Suspicious sender domain
Description	Detects suspicious sender domain age.
Severity	Medium
Tactics	InitialAccess
Techniques	T1566
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/CiscoSEG/Analytic Rules/CiscoSEGSuspiciousSenderDomain.yaml
Version	1.0.3
Arm template	ef0a253c-95b5-48e1-8ebc-dbeb073b9338.json

KQL

CiscoSEGEvent
| where NetworkDirection =~ 'Incoming'
| extend rec_domain = extract(@'@(.*)', 1, DstUserName)
| extend s_domain = extract(@'@(.*)', 1, SrcUserName)
| where s_domain != rec_domain
| where tostring(AdditionalFields) has 'ESASDRDomainAge'
| extend domain_age = extract(@'ESASDRDomainAge":"(.*days)"', 1, tostring(AdditionalFields))
| extend yy = toint(extract(@'(\d+)\syears', 1, domain_age))
| extend mm = toint(extract(@'(\d+)\smonths', 1, domain_age))
| extend dd = toint(extract(@'(\d+)\sdays', 1, domain_age))
| where isempty(yy)
| where isempty(mm) or mm <= 2
| extend AccountCustomEntity = SrcUserName

YAML

relevantTechniques:
- T1566
name: Cisco SEG - Suspicious sender domain
requiredDataConnectors:
- dataTypes:
  - CommonSecurityLog
  connectorId: CefAma
entityMappings:
- fieldMappings:
  - identifier: Name
    columnName: AccountCustomEntity
  entityType: Account
triggerThreshold: 0
id: ef0a253c-95b5-48e1-8ebc-dbeb073b9338
tactics:
- InitialAccess
version: 1.0.3
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/CiscoSEG/Analytic Rules/CiscoSEGSuspiciousSenderDomain.yaml
queryPeriod: 1h
kind: Scheduled
queryFrequency: 1h
severity: Medium
status: Available
description: |
    'Detects suspicious sender domain age.'
query: |
  CiscoSEGEvent
  | where NetworkDirection =~ 'Incoming'
  | extend rec_domain = extract(@'@(.*)', 1, DstUserName)
  | extend s_domain = extract(@'@(.*)', 1, SrcUserName)
  | where s_domain != rec_domain
  | where tostring(AdditionalFields) has 'ESASDRDomainAge'
  | extend domain_age = extract(@'ESASDRDomainAge":"(.*days)"', 1, tostring(AdditionalFields))
  | extend yy = toint(extract(@'(\d+)\syears', 1, domain_age))
  | extend mm = toint(extract(@'(\d+)\smonths', 1, domain_age))
  | extend dd = toint(extract(@'(\d+)\sdays', 1, domain_age))
  | where isempty(yy)
  | where isempty(mm) or mm <= 2
  | extend AccountCustomEntity = SrcUserName  
triggerOperator: gt

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/ef0a253c-95b5-48e1-8ebc-dbeb073b9338')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/ef0a253c-95b5-48e1-8ebc-dbeb073b9338')]",
      "properties": {
        "alertRuleTemplateName": "ef0a253c-95b5-48e1-8ebc-dbeb073b9338",
        "customDetails": null,
        "description": "'Detects suspicious sender domain age.'\n",
        "displayName": "Cisco SEG - Suspicious sender domain",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "AccountCustomEntity",
                "identifier": "Name"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/CiscoSEG/Analytic Rules/CiscoSEGSuspiciousSenderDomain.yaml",
        "query": "CiscoSEGEvent\n| where NetworkDirection =~ 'Incoming'\n| extend rec_domain = extract(@'@(.*)', 1, DstUserName)\n| extend s_domain = extract(@'@(.*)', 1, SrcUserName)\n| where s_domain != rec_domain\n| where tostring(AdditionalFields) has 'ESASDRDomainAge'\n| extend domain_age = extract(@'ESASDRDomainAge\":\"(.*days)\"', 1, tostring(AdditionalFields))\n| extend yy = toint(extract(@'(\\d+)\\syears', 1, domain_age))\n| extend mm = toint(extract(@'(\\d+)\\smonths', 1, domain_age))\n| extend dd = toint(extract(@'(\\d+)\\sdays', 1, domain_age))\n| where isempty(yy)\n| where isempty(mm) or mm <= 2\n| extend AccountCustomEntity = SrcUserName\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "InitialAccess"
        ],
        "techniques": [
          "T1566"
        ],
        "templateVersion": "1.0.3",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}